Improve Heltec v4 RX reception with undocumented register patch #1398

Socalix · 2026-01-14T23:57:20Z

Following several rounds of testing Heltec v4 RX reception as part of PR #1249 I found out that the best solution was using the original v1.11.0 code, with undocumented register 0x8B5 patch (setting LSB=1) as desribed by @Quency-D (Heltec engineer) here: #1249 (comment) ~~and without the RX Boosted Gain feature~~.

This PR is doing just that: turning on the 0x8B5 LSB ~~and turning off RX Boosted Gain flag.~~

UPDATE: After several rounds of testing here we determined that Boosted Gain flag should be turned on/off on a case-by-case basis, so this PR is now updated to only set the register value that has proven to consistently improve RX.

=== Additional Details ===

Test Process:
I put RAK4631 and Heltec v4, both with Alfa 915 antenna and repeater v1.11.0 firmware in the same location (attic, about 7 inches apart). I then took Heltec T114 with companion v1.11.0 about 1.25km (0.75mile) away and did ping every 3 seconds to the same repeater about 20-30 times. I then flashed the v4 with different firmwares and pinged again.

Test Sample:

RAK4631 v1.11.0	Heltec v4 PR1249 w/o RegPatch	Heltec v4 PR1249 w/RegPatch	Heltec v4 PR1398 w/RegPatch and no Boosted Gain
-4.25	err	4.75	5.5
err	err	err	6.25
-2.75	err	2.75	err
3.75	3.5	err	4.25
1.75	5.5	2.0	5.5
3.0	err	6.0	4.75
err	err	err	1.25
1.75	4.75	err	7.75
4.0	3.25	-0.25	err
4.75	3.0	1.75	2.5
-7.5	4.25	5.0	2.0
6.75	4.25	2.25	err
err	err	err	5.5
6.25	err	4.0	0.25
3.75	err	-0.75	err
20% err	55% err	33% err	25% err

Socalix · 2026-01-15T00:09:49Z

UPDATE (2026-01-22) - Repeater builds:

heltec_v4_repeater-1.11.0-pr1398-builds2.zip

pr1398-boost_on - Standard build without any extra flags (Boosted Gain on)
pr1398-boost_off - Standard build and Boosted Gain off
pr1398-boost_on-packetlog - Build with MESH_PACKET_LOGGING on and Boosted Gain on
pr1398-boost_off-packetlog - Build with MESH_PACKET_LOGGING on and Boosted Gain off

====

[OLD BUILDS] Repeater builds for testing:

pr1398 - Standard build - without any extra flags
pr1398-debug - Debug build - with USB_MODE, USB_CDC, MESH_DEBUG, MESH_PACKET_LOGGING flags
pr1398-packetlog - Standard build with MESH_PACKET_LOGGING flag only
pr1398-boost-packetlog - Standard build with RX_BOOSTED_GAIN and MESH_PACKET_LOGGING flags

spiralshapeturtle · 2026-01-15T07:21:06Z

@Socalix thanks for this spinoff. It would get more traction if you embed the table from your last post in the other PR with the results.

Would you do me a favor for the letsmesh MQTT output the debugging should be off to keep my RS232 stable.

Could you build a set with this flag only?

I love to test the files.

Build firmware with the -D MESH_PACKET_LOGGING=1 flag enabled using PLATFORMIO_BUILD_FLAGS.

PS: I have a cavity I could test with the RX boosted gain also. But not want to mesh up your PR. Let me know.

olanwe · 2026-01-15T11:20:47Z

I guess that this patch can also be applied to the Heltec Tracker v2.

weebl2000 · 2026-01-15T13:05:30Z

I guess that this patch can also be applied to the Heltec Tracker v2.

See also this branch: https://github.com/weebl2000/MeshCore/tree/semtech_patch - I've added it for Heltec Tracker v2 there.

I'm not sure about the boosted gain=0. For me it seems boosted gain still improves reception.

Socalix · 2026-01-15T19:04:34Z

@Socalix thanks for this spinoff. It would get more traction if you embed the table from your last post in the other PR with the results.

Good idea. PR summary updated with testing information.

Would you do me a favor for the letsmesh MQTT output the debugging should be off to keep my RS232 stable.
Build firmware with the -D MESH_PACKET_LOGGING=1 flag enabled using PLATFORMIO_BUILD_FLAGS.
PS: I have a cavity I could test with the RX boosted gain also. But not want to mesh up your PR. Let me know.

Updated the zip file above with a new "pr1398-packetlog" and "pr1398-boost-packetlog" builds.

Socalix · 2026-01-15T19:08:10Z

I guess that this patch can also be applied to the Heltec Tracker v2.

Yes, you can simply add -D SX126X_REGISTER_PATCH=1 flag and comment out SX126X_RX_BOOSTED_GAIN in the heltec_tracket_v2/platformio.ini file to turn it on.
I don't have Tracker v2, so I cannot test it myself.

spiralshapeturtle · 2026-01-15T20:25:56Z

@Socalix thanks for this spinoff. It would get more traction if you embed the table from your last post in the other PR with the results.

Good idea. PR summary updated with testing information.

Would you do me a favor for the letsmesh MQTT output the debugging should be off to keep my RS232 stable.
Build firmware with the -D MESH_PACKET_LOGGING=1 flag enabled using PLATFORMIO_BUILD_FLAGS.
PS: I have a cavity I could test with the RX boosted gain also. But not want to mesh up your PR. Let me know.

Updated the zip file above with a new "pr1398-packetlog" and "pr1398-boost-packetlog" builds.

Thanks my second V4 arrived today going to test on the similar antennas.

excalq · 2026-01-15T23:03:32Z

Thanks for this fix! I've been tying to get my v4 node connected to the area mesh, and though I could TX fine (packets seen on analyze.letsmesh.net), I rarely was getting responses. Tried 5 different antennas. This branches firmware seemed to have solved all the issues for me.

spiralshapeturtle · 2026-01-17T09:03:06Z

@Socalix

It's quite difficult to test here because the mesh network is so busy that the ping test you performed isn't possible at my location. There are too many transmissions which could interfere with pings from other locations. Both units are running quite stable, though one of them has a 2% higher RX (receive) level. I'll swap the antennas tonight (by changing the pigtail cables) to see if the 2% increase is related to the unit itself or the antenna.

Any other tips for testing are welcome.
1.11.0-pr1398-boost-packetlog-4575800 (Build: 15-Jan-2026)

1.11.0-pr1398-packetlog-4575800 (Build: 15-Jan-2026)

Socalix · 2026-01-17T21:25:35Z

It's quite difficult to test here because the mesh network is so busy that the ping test you performed isn't possible at my location. There are too many transmissions which could interfere with pings from other locations.

@spiralshapeturtle Thank you for testing! Yep, I'm "lucky" to be the only one running Meshcore around me.. :)
You may try a different frequency that may be less busy in your area. It's a bit tough in EU because there's not much bandwidth available, but if you're on 869.618 Mhz right now, maybe try 869.432 Mhz ?

Both units are running quite stable, though one of them has a 2% higher RX (receive) level. I'll swap the antennas tonight (by changing the pigtail cables) to see if the 2% increase is related to the unit itself or the antenna.

Looks like the one without the RX Boosted Gain has around 3db lower noise floor, which could translate to 2% more lower-signal packets getting picked up. Of course can also be antenna and location related, so switching things around will be interesting.

Since you have 6% TX, I wonder if having both repeaters running next to each other at the same time means that we're seeing them helping each other get more packets? i.e. only one repeater hears the original packet and the other repeater hears the packet from the first one repeating it, so the RX % will be similar.
It'd be interesting to see the RX % if you disable the repeaters "repeat mode" settings.

spiralshapeturtle · 2026-01-18T12:54:05Z

@Socalix test without TX mode.
Firmware: 1.11.0-pr1398-packetlog-4575800 (Build: 15-Jan-2026)

Firmware: 1.11.0-pr1398-boost-packetlog-4575800 (Build: 15-Jan-2026)

Well I have run them without TX for a while and I put the SNR/RSSI values into claude.ai. Below the summary which I can reuse upcoming week after swapping the pigtails today. Im only swapping the IPX connector on the boards and keep everything the same. As stated earlier I have to different antennas so that could still be a factor to mitigate by swapping the connectors.

WARNING below is an AI generated summary.

# MeshCore Transceiver Comparison

## Utrecht Node
**Distance:** boost-packetlog: 13.69 km | packetlog: 13.64 km

| Firmware | Time Ago | SNR  | RSSI    | Score |
|----------|----------|------|---------|-------|
| boost-packetlog | 1h ago | 0dB | -74dBm | 579 |
| boost-packetlog | 2h ago | 4dB | -75dBm | 795 |
| boost-packetlog | 3h ago | 5dB | -74dBm | 822 |
| packetlog | 1h ago | 3dB | -79dBm | 741 |
| packetlog | 2h ago | 6dB | -78dBm | 902 |
| packetlog | 3h ago | 6dB | -77dBm | 902 |

**Winner: packetlog** - Higher SNR (6dB vs 5dB best), better scores (902 vs 822 peak)

---

## Repeater PA5B Houten
**Distance:** 7.25 km (Only visible on packetlog)

| Firmware | Time Ago | SNR   | RSSI    | Score |
|----------|----------|-------|---------|-------|
| boost-packetlog | - | - | - | - |
| packetlog | 1h ago | -1dB | -90dBm | 439 |
| packetlog | 3h ago | -3dB | -89dBm | 317 |
| packetlog | 4h ago | -4dB | -89dBm | 256 |

**Winner: packetlog** - Only firmware that can reach this node

---

## Radome West
**Distance:** boost-packetlog: 4.06 km | packetlog: 3.93 km

| Firmware | Time Ago | SNR  | RSSI    | Score |
|----------|----------|------|---------|-------|
| boost-packetlog | 3h ago | 3dB | -71dBm | 719 |
| packetlog | 4h ago | 6dB | -73dBm | 837 |

**Winner: packetlog** - Better SNR (6dB vs 3dB), higher score (837 vs 719)

---

## Zeist Sanatoriumbos
**Distance:** boost-packetlog: 2.66 km | packetlog: 2.62 km

| Firmware | Time Ago | SNR   | RSSI    | Score |
|----------|----------|-------|---------|-------|
| boost-packetlog | 7h ago | -4dB | -94dBm | 270 |
| packetlog | 8h ago | -9dB | -97dBm | 36 |

**Winner: boost-packetlog** - Much better SNR (-4dB vs -9dB), significantly higher score (270 vs 36)

---

## Overall Performance Summary

| Metric | boost-packetlog | packetlog |
|--------|-----------------|-----------|
| **Nodes Reached** | 3 | 4 |
| **Best SNR** | 5dB (Utrecht) | 6dB (Utrecht, Radome West) |
| **Best Score** | 822 (Utrecht) | 902 (Utrecht) |
| **Worst Score** | 270 (Zeist) | 36 (Zeist) |
| **Average Score** | 648 | 597 |

## Key Observations

- **packetlog firmware** has better reach (4 nodes vs 3) and can connect to the PA5B Houten repeater
- **packetlog firmware** performs significantly better on distant nodes (Utrecht, Radome West) with superior SNR
- **boost-packetlog firmware** handles the closest node (Zeist Sanatoriumbos) much better - 7.5x higher score
- **packetlog firmware** shows more consistent high scores on medium-to-long range links
- **boost-packetlog firmware** may have better near-field rejection or less sensitivity to local interference
- Both firmwares struggle with Zeist Sanatoriumbos despite it being the closest node (possible obstruction or antenna issue)

## Recommendation

**Use packetlog firmware for general meshing** - Superior long-range performance (better SNR on distant nodes) and reaches more nodes including the PA5B Houten repeater. The "boost" variant doesn't appear to provide range advantages and actually performs worse on most metrics except the problematic nearest node.

**Note:** The "boost" in boost-packetlog firmware doesn't translate to better range or scores. Consider investigating if boost settings are causing near-field saturation or gain compression.

towerviewcams · 2026-01-18T23:21:25Z

Here is a big question and I'm hoping someone can help. How can we use this running Powersaving10 firmware so that we can turn off the LNA pre-amp at noisy tower sites. This would be a game changer. But we cant use the standard 1.11 firm as it draws to much power. suggestions ?

1/19/2026 update - its there already...... "powersaving on" and your set

Socalix · 2026-01-18T23:38:25Z

Well I have run them without TX for a while and I put the SNR/RSSI values into claude.ai. Below the summary which I can reuse upcoming week after swapping the pigtails today. Im only swapping the IPX connector on the boards and keep everything the same. As stated earlier I have to different antennas so that could still be a factor to mitigate by swapping the connectors.

WARNING below is an AI generated summary.
Use packetlog firmware for general meshing - Superior long-range performance (better SNR on distant nodes) and reaches more nodes including the PA5B Houten repeater. The "boost" variant doesn't appear to provide range advantages and actually performs worse on most metrics except the problematic nearest node.

These tests are great! The difference of 20% RX with Boosted Gain and 25% without boost I believe confirms that TX enabled in the prior test let the repeaters "help" each other hear packets, so definitely TX disabled is the right way to test. Also 5% difference by itself may not sound much, but it's 25% better RX over the one with boosted gain.

I also agree with the AI summary as it matches my previous tests - boosted gain is reducing the node's ability to hear some packets and causes the SNR overall to be lower.

After you complete the test with flipped antennas, it would be great if you don't mind running one more test - pr1398-packetlog vs standard v1.11.0 so that we can see the RX difference there.

Socalix · 2026-01-18T23:50:33Z

Here is a big question and I'm hoping someone can help. How can we use this running Powersaving10 firmware so that we can turn off the LNA pre-amp at noisy tower sites. This would be a game changer. But we cant use the standard 1.11 firm as it draws to much power. suggestions ?

This PR fix includes 2 things:

Register patch - which I do not expect to change power consumption.
Turning off Boosted Gain feature - which I would expect to lower power consumption a little.
Unfortunately, I do not have the means to test and measure this right now. You could apply the same fix to the Power-saving version and test.

towerviewcams · 2026-01-19T00:34:14Z

Here is a big question and I'm hoping someone can help. How can we use this running Powersaving10 firmware so that we can turn off the LNA pre-amp at noisy tower sites. This would be a game changer. But we cant use the standard 1.11 firm as it draws to much power. suggestions ?

This PR fix includes 2 things:

Register patch - which I do not expect to change power consumption.

Turning off Boosted Gain feature - which I would expect to lower power consumption a little.
Unfortunately, I do not have the means to test and measure this right now. You could apply the same fix to the Power-saving version and test.

I have the test equipment to test this but my knowledge on how to modify the code is where Iack. Is this a command line entry? what do i download and how how do I bring it up and I'll find the rest.

So I have the powersaving10 file and what to do from there?

spiralshapeturtle · 2026-01-19T06:15:02Z

Here is a big question and I'm hoping someone can help. How can we use this running Powersaving10 firmware so that we can turn off the LNA pre-amp at noisy tower sites. This would be a game changer. But we cant use the standard 1.11 firm as it draws to much power. suggestions ?

I don't know how it works with the file and coding, but I can tell you that on my V4 I can use the "powersaving on|off" command. So it might come with the nightly builds where the power saving is already included for the v1.12.0 release.

Just type "powersaving on"

For the record my tests are done without powersaving enabled.

tpp-at-idx · 2026-01-19T08:04:23Z

Hello guys, I was doing some tests on #1249 and while i was on it I also tried this PR. Here is a crosspost from the findings

Hello guys
I've run some tests as promised
Thease are all based on the BLE companion firmware. With one reference node in a good RF environment, out of the window, which is persumed to receive all messages, and with the testing node being a V4 placed in my "rf hellhole" ( noisy monitors, PC's, noise floor about -70 to -75 ).
The test was to receive ~ 300 messages on the reference node and then compare how many messages were lost on the tested node. Take this with a grain of salt, I've tried to make it as scientific as possible but the methodology may be flawed upon factors i can not really control and it is all i could do with my limited resources

Stock firmware: Reference: 296 messages, V4 received: 284, loss: 4 %
TXRX lna patch: Reference: 239 messages, V4 received: 229, loss: 4,1 %
Semtech only patch : Reference: 307 messages, V4 received: 302, loss: 1,6 %
RXgain off +semtech patch ( #1398 ) : Reference: 266, V4 received: 252, loss: 5,2 %

spiralshapeturtle · 2026-01-19T13:33:09Z

@Socalix I only swapped the antenna IPX connector and now 24 hours later the result is as follow. AI summarized the data.

Firmware: 1.11.0-pr1398-boost-packetlog-4575800 (Build: 15-Jan-2026)

Firmware: 1.11.0-pr1398-packetlog-4575800 (Build: 15-Jan-2026)

PA5B Houten repeater is quite far away from me and that seems to be the differentiator, more on that at the bottom.

# MeshCore Firmware Comparison: boost-packetlog vs packetlog

## Test Setup

**Hardware:** Two identical transceivers with same coax length, roof-mounted 2 types of antennas  
**Test Method:** Antenna swap to isolate firmware differences from antenna performance

| Device | Firmware Version | Current Antenna |
|--------|-----------------|-----------------|
| V4_2 | 1.11.0-pr1398-boost-packetlog-4575800 | Without tape |
| V4 | 1.11.0-pr1398-packetlog-4575800 | With tape |

---

## Node Statistics - V4_2 (boost-packetlog)

### Utrecht
**Distance:** 13.69 km (8.50 mi)

| Time Ago | SNR  | RSSI    | Score |
|----------|------|---------|-------|
| 1h ago   | 4dB  | -77dBm  | 696   |
| 3h ago   | 2dB  | -80dBm  | 612   |
| 5h ago   | 3dB  | -78dBm  | 636   |

### Radome West
**Distance:** 4.06 km (2.52 mi)

| Time Ago | SNR  | RSSI    | Score |
|----------|------|---------|-------|
| 4h ago   | 8dB  | -73dBm  | 955   |
| 16h ago  | 5dB  | -74dBm  | 824   |
| 1d ago   | 3dB  | -71dBm  | 719   |

### Zeist Slot
**Distance:** 0.91 km (0.56 mi)

| Time Ago | SNR  | RSSI    | Score |
|----------|------|---------|-------|
| 35m ago  | 1dB  | -73dBm  | 593   |
| 12h ago  | 2dB  | -78dBm  | 672   |

### loramesh.nl
**Distance:** 8.02 km (4.98 mi)

| Time Ago | SNR   | RSSI    | Score |
|----------|-------|---------|-------|
| 3h ago   | -1dB  | -85dBm  | 458   |

### Zeist Sanatoriumbos
**Distance:** 2.66 km (1.65 mi)

| Time Ago | SNR   | RSSI    | Score |
|----------|-------|---------|-------|
| 1d ago   | -4dB  | -94dBm  | 270   |

---

## Node Statistics - V4 (packetlog)

### Utrecht
**Distance:** 13.64 km (8.48 mi)

| Time Ago | SNR  | RSSI    | Score |
|----------|------|---------|-------|
| 3h ago   | 0dB  | -75dBm  | 516   |
| 5h ago   | 1dB  | -74dBm  | 540   |
| 7h ago   | 2dB  | -74dBm  | 600   |

### Repeater PA5B Houten
**Distance:** 7.25 km (4.51 mi)

| Time Ago | SNR   | RSSI    | Score |
|----------|-------|---------|-------|
| 8h ago   | -1dB  | -86dBm  | 415   |
| 12h ago  | -1dB  | -86dBm  | 415   |
| 1d ago   | -1dB  | -90dBm  | 439   |

### Radome West
**Distance:** 3.93 km (2.44 mi)

| Time Ago | SNR   | RSSI    | Score |
|----------|-------|---------|-------|
| 4h ago   | 4dB   | -74dBm  | 758   |
| 16h ago  | -2dB  | -72dBm  | 418   |
| 1d ago   | 6dB   | -73dBm  | 837   |

### Zeist Sanatoriumbos
**Distance:** 2.62 km (1.63 mi)

| Time Ago | SNR   | RSSI    | Score |
|----------|-------|---------|-------|
| 1d ago   | -9dB  | -97dBm  | 36    |

---
`



`
## Firmware Comparison (Recent 8-Hour Window)

| Node | Distance | boost-packetlog | packetlog | Winner |
|------|----------|-----------------|-----------|--------|
| **Utrecht** | ~13.6 km | 4dB / -77dBm / **696** | 0dB / -75dBm / 516 | boost (+35%) |
| **Radome West** | ~4.0 km | 8dB / -73dBm / **955** | 4dB / -74dBm / 758 | boost (+26%) |
| **PA5B Houten** | 7.25 km | ❌ Not seen | -1dB / -86dBm / 415 | packetlog (only) |
| **loramesh.nl** | 8.02 km | -1dB / -85dBm / 458 | ❌ Not seen | boost (only) |
| **Zeist Slot** | 0.91 km | 1dB / -73dBm / 593 | ❌ Not seen | boost (only) |

---

## Performance Metrics Summary

| Metric | boost-packetlog (V4_2) | packetlog (V4) |
|--------|------------------------|----------------|
| **Peak Score** | 955 (Radome West) | 758 (Radome West) |
| **Best SNR** | 8dB (Radome West) | 6dB (Radome West, old data) |
| **Nodes Reached** | 5 unique nodes | 4 unique nodes |
| **Best RSSI** | -71dBm | -72dBm |
| **Average Score (top 3)** | 749 | 631 |

---

## Key Observations

### 1. **Score Performance**
- boost-packetlog consistently achieves **20-35% higher scores** on shared nodes
- Utrecht: 696 vs 516 (+35%)
- Radome West: 955 vs 758 (+26%)

### 2. **SNR Quality**
- boost-packetlog shows **superior noise rejection**
- Peak SNR: 8dB vs 6dB (+2dB improvement)
- Better SNR even at similar RSSI levels (-77dBm vs -75dBm on Utrecht)

### 3. **Node Discovery**
- **boost-packetlog** sees more local nodes (Zeist Slot, loramesh.nl)
- **packetlog** sees the PA5B Houten repeater (boost does not)
- Different packet filtering/decoding strategies

### 4. **Range Performance**
- Both reach Utrecht at ~13.6 km
- boost-packetlog maintains better link quality at distance
- Similar sensitivity (-77dBm vs -75dBm best RSSI)

### 5. **Repeater Compatibility**
- **Critical difference:** Only packetlog firmware can decode the PA5B Houten repeater
- Repeater has marginal SNR (-1dB) which boost firmware may reject
- Suggests more permissive decoding in packetlog

---

## Technical Analysis

### boost-packetlog Characteristics:
- ✅ Superior noise floor management (higher SNR)
- ✅ Better score calculation algorithm
- ✅ Excellent near-field performance (0.91 km node)
- ✅ More aggressive gain settings
- ❌ Stricter packet filtering (misses marginal repeater)
- ❌ May reject valid but noisy packets

### packetlog Characteristics:
- ✅ More permissive packet decoding
- ✅ Better repeater compatibility
- ✅ Decodes packets with negative SNR (-1dB)
- ✅ Maximum mesh connectivity
- ❌ Lower overall scores
- ❌ Misses some local nodes

---

## Antenna vs Firmware - Critical Finding

**After antenna swap, performance patterns remained identical:**
- boost-packetlog still achieves higher scores on same nodes
- packetlog still sees PA5B Houten repeater
- Same node visibility patterns persist

**Conclusion:** Performance differences are **firmware-based, not antenna-based**. The antenna swap test confirms that the "boost" and standard firmware builds have fundamentally different radio characteristics.

---

## Conclusion

The firmware comparison reveals **significant algorithmic differences** between boost-packetlog and standard packetlog builds:

1. **boost-packetlog** delivers 20-35% higher scores and 2dB better SNR on shared nodes
2. **packetlog** provides better mesh network compatibility by accepting marginal packets
3. The "boost" variant is **not just a power adjustment** - it implements different signal processing
4. Neither firmware is strictly "better" - they serve different network architectures

**Final Verdict:** For standalone/gateway use, boost-packetlog is superior. For mesh networks with repeaters, standard packetlog is essential. The optimal solution is running both firmwares on separate devices to leverage the strengths of each.

**Hardware confirmation:** Antenna swap test proves these differences are purely firmware-based, not hardware-dependent.

I asked AI again about the far away repeater, arround 2 PM I changed the antenna cable where you can see the load rising and lowering, so the antenna with the tape label is better.

Yesterday the (better) antenna with the tape label was on this node:
Firmware: 1.11.0-pr1398-packetlog-4575800 (Build: 15-Jan-2026)
V4 antenne met tape

This 24hours I swaped the (better) tape labeled antenna to this node
Firmware: 1.11.0-pr1398-boost-packetlog-4575800 (Build: 15-Jan-2026)
V4_2

# PA5B Houten Repeater - Detection Analysis

## Detection History

| Date | Firmware | Device | Detected? | Best Stats |
|------|----------|--------|-----------|------------|
| **Yesterday** | packetlog | V4 | ✅ YES | -1dB / -90dBm / 439 |
| **Yesterday** | boost-packetlog | V4_2 | ❌ NO | - |
| **Today** | packetlog | V4 | ✅ YES | -1dB / -86dBm / 415 |
| **Today** | boost-packetlog | V4_2 | ❌ NO | - |

---

## Key Finding

**PA5B Houten repeater (7.25 km) is ONLY visible on packetlog firmware**

### Yesterday's Configuration:
- **V4_2** (boost-packetlog) had antenna **with tape** → Did NOT see repeater
- **V4** (packetlog) had antenna **without tape** → SAW repeater

### Today's Configuration (after antenna swap):
- **V4_2** (boost-packetlog) now has antenna **without tape** → Still does NOT see repeater
- **V4** (packetlog) now has antenna **with tape** → Still SEES repeater

---

## Conclusion

🎯 **The PA5B Houten repeater detection is 100% firmware-dependent, NOT antenna-dependent**

### Evidence:
1. **Consistent across antenna swap** - packetlog sees it regardless of which antenna
2. **Never seen by boost-packetlog** - even with the "better" antenna (without tape)
3. **Marginal signal quality** - Repeater operates at -1dB SNR, which boost firmware likely rejects
4. **RSSI improvement** - Today's measurement shows -86dBm vs yesterday's -90dBm (4dB better with "worse" antenna), proving firmware decoding difference

### Technical Explanation:
- PA5B Houten has **marginal SNR (-1dB)** 
- **boost-packetlog** firmware has stricter packet acceptance threshold
- **packetlog** firmware accepts packets with negative SNR
- This is a **decoding strategy difference**, not a sensitivity difference

**Answer:** Only **packetlog firmware** saw the PA5B Houten repeater, both yesterday AND today, regardless of antenna configuration.

weebl2000 · 2026-01-19T13:50:25Z

@spiralshapeturtle Can you also clarify which changes the boost-packetlog and packetlog firmwares contain?

boost-packetlog -> is this boosted_gain=0 and the register fix?

spiralshapeturtle · 2026-01-19T13:56:34Z

@spiralshapeturtle Can you also clarify which changes the boost-packetlog and packetlog firmwares contain?

boost-packetlog -> is this boosted_gain=0 and the register fix?

#1398 (comment) i just copied this, the only thing I know.

Socalix · 2026-01-19T14:20:04Z

@spiralshapeturtle Can you also clarify which changes the boost-packetlog and packetlog firmwares contain?

boost-packetlog -> is this boosted_gain=0 and the register fix?

packetlog = this PR which means register patch and NO boosted gain flag turned on.
boost-packetlog = register patch WITH boosted gain flag turned on.

Socalix · 2026-01-19T14:21:45Z

Hello guys I've run some tests as promised Thease are all based on the BLE companion firmware. With one reference node in a good RF environment, out of the window, which is persumed to receive all messages, and with the testing node being a V4 placed in my "rf hellhole" ( noisy monitors, PC's, noise floor about -70 to -75 ). The test was to receive ~ 300 messages on the reference node and then compare how many messages were lost on the tested node. Take this with a grain of salt, I've tried to make it as scientific as possible but the methodology may be flawed upon factors i can not really control and it is all i could do with my limited resources

Thanks for testing! This is an interesting test and results. What antennas are you using on these nodes?
I'm also wondering if it's possible for you to test with both antennas in the same area (in/out window) several inches apart? Also, if you could put on one node Boosted gain off and one Boosted gain on for comparison?

Socalix · 2026-01-19T14:32:28Z

@Socalix I only swapped the antenna IPX connector and now 24 hours later the result is as follow. AI summarized the data.
I asked AI again about the far away repeater, arround 2 PM I changed the antenna cable where you can see the load rising and lowering, so the antenna with the tape label is better.

I think the AI summary is a bit confusing today, but if I understand the letsmesh graphs correctly - what we see today is that antenna choice has a bigger impact on RX % than boosted gain flag. We still see the same 20% RX vs 25% RX on the same antennas regardless of the boosted gain. Correct?

tpp-at-idx · 2026-01-19T14:49:36Z

Thanks for testing! This is an interesting test and results. What antennas are you using on these nodes? I'm also wondering if it's possible for you to test with both antennas in the same area (in/out window) several inches apart? Also, if you could put on one node Boosted gain off and one Boosted gain on for comparison?

Antenna is: https://www.laskakit.cz/nicerf-sw868-zd210-antena-3dbi-21cm-868mhz/ ( on both nodes )

Also for the additional tests:
I will try to whip up a testcase for that ( both nodes side by side, one with rx_gain off, one with rx_gain on ) Will report in a few days. But I must note that the message count discrepancy is mostly visible in my "rf hellhole" that has a noise floor of -70 to -75, I live in a nicely covered area in the vincity of 5 superb repeaters who beam a constant +10 db my way, so, yeah. It really does not make any sence to put both tested nodes in the window ( and in that location the v4 sees a noise floor of -95 to -105 )

spiralshapeturtle · 2026-01-19T14:56:29Z

@Socalix I only swapped the antenna IPX connector and now 24 hours later the result is as follow. AI summarized the data.

I asked AI again about the far away repeater, arround 2 PM I changed the antenna cable where you can see the load rising and lowering, so the antenna with the tape label is better.

I think the AI summary is a bit confusing today, but if I understand the letsmesh graphs correctly - what we see today is that antenna choice has a bigger impact on RX % than boosted gain flag. We still see the same 20% RX vs 25% RX on the same antennas regardless of the boosted gain. Correct?

Correct! The packet increase is related to the better antenna.

But the interesting part is this see the distance table.

Edit: can copy it on mobile will do tonight.

Antenna Swap Test Results - Yesterday vs Today

Test Configuration

Day	V4_2 (boost-packetlog)	V4 (packetlog)
Yesterday	Better antenna	Standard antenna
Today	Standard antenna	Better antenna

Better antenna = Original antenna without tape
Standard antenna = Antenna with tape label

Complete Node Detection & Performance Comparison

Utrecht Node (~13.6 km)

Day	Firmware	Antenna	SNR	RSSI	Score	Change
Yesterday	boost-packetlog	Better	5dB	-74dBm	822	-
Today	boost-packetlog	Standard	4dB	-77dBm	696	⬇️ -15% score
Yesterday	packetlog	Standard	6dB	-77dBm	902	-
Today	packetlog	Better	0dB	-75dBm	516	⬇️ -43% score

Key Finding: Both firmwares show significant performance degradation with standard antenna

Radome West Node (~4.0 km)

Day	Firmware	Antenna	SNR	RSSI	Score	Change
Yesterday	boost-packetlog	Better	3dB	-71dBm	719	-
Today	boost-packetlog	Standard	8dB	-73dBm	955	⬆️ +33% score
Yesterday	packetlog	Standard	6dB	-73dBm	837	-
Today	packetlog	Better	4dB	-74dBm	758	⬇️ -9% score

Key Finding: Anomaly - boost-packetlog improved with standard antenna (likely temporal variation)

PA5B Houten Repeater (7.25 km)

Day	Firmware	Antenna	SNR	RSSI	Score	Detection
Yesterday	boost-packetlog	Better	-	-	-	❌ Not detected
Today	boost-packetlog	Standard	-	-	-	❌ Not detected
Yesterday	packetlog	Standard	-1dB	-90dBm	439	✅ Detected
Today	packetlog	Better	-1dB	-86dBm	415	✅ Detected

Key Finding: Only packetlog firmware detects this repeater, regardless of antenna

Zeist Slot (0.91 km) - Local Node

Day	Firmware	Antenna	SNR	RSSI	Score	Detection
Yesterday	boost-packetlog	Better	-	-	-	❓ No data
Today	boost-packetlog	Standard	1dB	-73dBm	593	✅ Detected
Yesterday	packetlog	Standard	-	-	-	❌ Not detected
Today	packetlog	Better	-	-	-	❌ Not detected

Key Finding: Only boost-packetlog detects this local node

loramesh.nl (8.02 km)

Day	Firmware	Antenna	SNR	RSSI	Score	Detection
Yesterday	boost-packetlog	Better	-	-	-	❓ No data
Today	boost-packetlog	Standard	-1dB	-85dBm	458	✅ Detected
Yesterday	packetlog	Standard	-	-	-	❌ Not detected
Today	packetlog	Better	-	-	-	❌ Not detected

Key Finding: Only boost-packetlog detects this node

Zeist Sanatoriumbos (2.66 km) - Problem Node

Day	Firmware	Antenna	SNR	RSSI	Score	Detection
Yesterday	boost-packetlog	Better	-4dB	-94dBm	270	✅ Detected
Today	boost-packetlog	Standard	-	-	-	❌ Not detected (1d old)
Yesterday	packetlog	Standard	-9dB	-97dBm	36	✅ Poor detection
Today	packetlog	Better	-	-	-	❌ Not detected (1d old)

Key Finding: Node has become unreachable for both setups today

Summary Statistics

Node Reach Comparison

Configuration	Nodes Detected	Unique Nodes	Total Observations
Yesterday - boost + Better antenna	3	Utrecht, Radome, Zeist Sanat	5 measurements
Today - boost + Standard antenna	4	Utrecht, Radome, Zeist Slot, loramesh	7 measurements
Yesterday - packetlog + Standard antenna	4	Utrecht, PA5B, Radome, Zeist Sanat	7 measurements
Today - packetlog + Better antenna	3	Utrecht, PA5B, Radome	6 measurements

Performance Changes After Antenna Swap

V4_2 (boost-packetlog): Better → Standard Antenna

Node	Yesterday Score	Today Score	Change
Utrecht	822	696	⬇️ -15%
Radome West	719	955	⬆️ +33% (anomaly)
Zeist Sanatoriumbos	270	-	Lost contact
Zeist Slot	-	593	🆕 New detection
loramesh.nl	-	458	🆕 New detection

Net Result: +2 nodes, -1 node, mixed performance

V4 (packetlog): Standard → Better Antenna

Node	Yesterday Score	Today Score	Change
Utrecht	902	516	⬇️ -43%
Radome West	837	758	⬇️ -9%
PA5B Houten	439	415	⬇️ -5%
Zeist Sanatoriumbos	36	-	Lost contact

Net Result: No new nodes, significant score decreases

Critical Observations

1. Antenna Performance is Complex

The "better antenna" shows:

✅ Higher peak scores on some nodes (Utrecht: 902 vs 516)
✅ Better RSSI on PA5B Houten (-86dBm vs -90dBm)
❌ Lower scores when swapped to boost firmware
❌ Lost Zeist Sanatoriumbos contact

2. Firmware Dominates Results

Finding	Evidence
PA5B Houten detection	Only packetlog, both antennas
Zeist Slot detection	Only boost-packetlog, both antennas
loramesh.nl detection	Only boost-packetlog, both antennas
Score patterns	Firmware-specific, persist across swap

3. Temporal Variations Matter

Radome West improved 33% despite "worse" antenna (likely weather/propagation)
Zeist Sanatoriumbos went offline on both setups (node issue, not antenna)
Time of day affects measurements significantly

V4 (packetlog) with Better antenna achieved the highest single score (902) and best SNR (6dB), making it the optimal choice for long-range mesh networking.

boost-packetlog excels at discovering local nodes but benefits less from the better antenna, suggesting its signal processing is optimized differently.

spiralshapeturtle · 2026-01-19T15:03:44Z

@Socalix which one should I flash with the regular firmware?

spiralshapeturtle · 2026-01-19T17:33:45Z

After you complete the test with flipped antennas, it would be great if you don't mind running one more test - pr1398-packetlog vs standard v1.11.0 so that we can see the RX difference there.

Yes did that! So packetlog v.s. standard is running now, where standard is on the better antenna and should get the same percentage RX.

towerviewcams · 2026-01-20T00:53:08Z

Just tested both the PR1398 packetlog and the PR1398 Boost Packetlog and both support Powersaving! This is amazing - I did not see this mentioned! it works!

To confirm, the PR1398-packetlog has the LNA (17db pre amp) DISABLED. Is this correct?
both firms have the Register Patch for the LSB=1.....Is this correct?

spiralshapeturtle · 2026-01-22T12:01:20Z

@Quency-D Theoretically, adding RXGAIN should yield better results when noise levels are low, but may have adverse effects when noise levels are high. Therefore, it's best to add this variable to the app so that it becomes controllable.

At this point I think all of our tests have proven that the register patch provided by @Quency-D is significantly improving RX in all cases and should be merged into the firmware.

As for the Booted Gain, we see that this seems to be more of a case-by-case basis, depending on environment, antenna, noise level, etc. Considering this is controlled by an existing build flag already, and there's an open PR #1164 to make it configurable at runtime too, I'm going to revert the boosted gain part of the PR and keep the register patch only.

Totally agree on that, thanks for your time invested. And for the record I put my V4 out in the field now:

heltec_v4_repeater-1.11.0-pr1398-4575800.bin this file from your links is the normal file without, debugs, packetlogs etc? Which I could load into my repeaters. This file is good to go until @Quency-D / Heltec managed to get this PR merged into the new builds.

Again thanks!

Socalix · 2026-01-22T19:30:37Z

@spiralshapeturtle I updated the builds zip up here #1398 (comment) with better names:

pr1398-boost_on - Standard build without any extra flags (Boosted Gain on)
pr1398-boost_off - Standard build and Boosted Gain off
pr1398-boost_on-packetlog - Build with MESH_PACKET_LOGGING on and Boosted Gain on
pr1398-boost_off-packetlog - Build with MESH_PACKET_LOGGING on and Boosted Gain off

towerviewcams · 2026-01-22T21:07:34Z

@spiralshapeturtle & @Socalix
The boost on and off does not apply to a V4 right? I don't see any receive gain difference flashing ether file. My understanding is thats for the older SX chip. correct?

Socalix · 2026-01-23T01:21:07Z

@spiralshapeturtle & @Socalix The boost on and off does not apply to a V4 right? I don't see any receive gain difference flashing ether file. My understanding is thats for the older SX chip. correct?

@towerviewcams The boost on/off is for the SX126X_RX_BOOSTED_GAIN flag. After all the testing that was done by different people here we could not identify one setting that's consistently better for everyone. It seems to be more of a case-by-case basis, depending on environment, antenna, noise level, etc. That's why I put 2 different builds - so anyone can experiment and choose whichever works best for them.

This is from Semtech documentation:
The SX1261 and SX1262 can operate in Rx Boosted gain setup or in a Rx power saving gain setup. In the Rx power saving gain, the radio will consume less power at a small cost in sensitivity. In Rx Boosted gain, the radio will consume more power to improve the sensitivity

spiralshapeturtle · 2026-01-23T05:08:16Z

Thanks @Socalix for your helpful answers. Tonight I created a PlatformIO builder myself, and it seems I'm able to build firmware on my own.

There is one small missing piece for me, and that is the default for the RX_BOOSTED_GAIN flag. From my own research, it seems the default is 1 (enabled) in the MeshCore GA builds. Since this PR opts in to the register patch and the default seems to be RX_BOOSTED_GAIN=1.

I should run a file with the "pr1398-boost_on" naming to match the results 1:1 in the near future when this goes to GA. Does my code analysis skills worked this out correctly😊?

Socalix · 2026-01-24T01:59:40Z

I should run a file with the "pr1398-boost_on" naming to match the results 1:1 in the near future when this goes to GA.

Correct. The official builds have Boosted Gain enabled (RX_BOOSTED_GAIN=1) by default.
Initially I started this PR with boosted off (flag commented out), but since we found out that there is no one good answer for everyone, I decided to go back to boosted enabled as the original.
I provided both build options in the zip above for those who don't know how to build on their own or prefer to just download and flash.

dt267 · 2026-01-24T03:55:21Z

How good is a Heltec V4 with the register patch compared to a Heltec V3?

spiralshapeturtle · 2026-01-24T08:50:39Z

How good is a Heltec V4 with the register patch compared to a Heltec V3?

Hard to put it in numbers. Close or even better? I think it still depends on the location. Close to a cell tower every LNA enabled device got a harder job than a none LNA enabled device. But out in the open field the LNA can surprise you.

With a cavity and this PR on my V4 with the default boost on 25-50km reach on a 9dBi McGill antenna. And a cell tower at 400meters. Of course these are the outliners, probably high remote locations. But the V4 is able to decode the packets.

dt267 · 2026-01-25T02:47:25Z

I performed some measurements on the Heltec V3 with the register patch, and it looks like the patch reduced the RSSI by 10dBm.

In theory, we have +13dBm (GC1109) - 10dBm = +3dBm, so the Heltec V4 should be better than the V3.
However, the error rate difference, 20% on Rak4631 versus 25% on Heltec v4 PR1398 w/RegPatch and no Boosted Gain, is making me nervous.
A cavity filter won't help if the noise is in-band. In this case, I'm more concerned about the LNA recovery capability of the SX1262.

dt267 · 2026-01-25T08:10:06Z

I found the answer myself. Here are the test results (two repeaters placed at the same location):

Conclusion: This register patch does not help the Heltec V4; it is still worse. I have to go back to my solution: bypassing the external LNA using a flying wire.

mikecarper · 2026-01-25T08:49:32Z

You have directions on how to do that flying wire? Also can you compare it like you did above?

dt267 · 2026-01-25T09:39:41Z

You have directions on how to do that flying wire? Also can you compare it like you did above?

Here are the test results (two repeaters placed at the same location):

Socalix · 2026-01-25T17:21:59Z

@dt267 Thanks for the interesting tests! In your first test (register patch with boosted gain on) the v4 received all the packets that v3 received, even though the reported RSSI and SNR were lower. This is a great improvement over what many of us experienced without the register patch, so it'll be interesting to see what you get as well.
Do you mind running one more test with the original v1.11.0 firmware (i.e. no register patch, with boosted gain on)?

In your second test where you compared the v3 with boosted gain vs the v4 without boosted gain, there is a significant difference in the v4 noise floor for some reason (-80 vs -115). I wonder why such a big difference, but I suspect the high noise floor impacted the packets received. Like I mentioned before, we noticed that boosted gain help in some cases and not so much in others. Looks like in your case boosted gain did help.

In your third test with LNA bypass - the results are very impressive! what firmware did you run on the v4? standard? with register patch? with boosted gain?

Conclusion: This register patch does not help the Heltec V4; it is still worse. I have to go back to my solution: bypassing the external LNA using a flying wire.

I disagree with "does not help" conclusion. I think what you meant is that the v4 with the register patch still performs worse than v3 or RAK4631 or v4 with LNA bypass, which all seem true.

Unfortunately, microscopic soldering to bypass the LNA is not something many of us can easily do. The register patch helps significantly over the standard firmware for those who cannot bypass the LNA. Maybe one day Heltec would recall v4.2 and send us all a v4.3 once they fix it? 😉

towerviewcams · 2026-01-25T20:14:29Z

@Socalix Bypassing the LNA is not that hard at all. its really not. Go to harbor freight and get a headset magnifying glass tool. It made ALL the difference for me. I have 3 deployed that are mod like this and its suppppper amazing. Basically, you get the 4630 receiver and +28.3 ish of transmit. I have some sites that have massive noise with a local PUD reading meters at 900Mhz and a rak would survive at -98 ish noise floor. V4 ha ha no way..... now with LNA truly gone, noise floor is the same or maybe 2db better at most. I also tape (super 33+) and shield my V4 with 4 wraps of tin foil inside my case. works so nicely and i can still WiFi OTA with my phone within 25ft of the board.

Now, the register patch is defiantly better then current stock firm (1.11) or even the powersaving11.2 Having all these options is key and the work that's gone into the register patch great.

my conclusion -
when I deploy a new repeater, I take two complete solar / V4 setups. one with LNA and one with LNA bypassed. Install antenna and sweep. then, test the 2 and leave one that has the best overall results. I do this during heavy traffic times at our commercial tower sites so that the noise floor is at its worst.... ether 7am-9am or 3pm-6pm....... Makes ALL the difference for true readings.

Socalix · 2026-01-25T21:10:26Z

@Socalix Bypassing the LNA is not that hard at all. its really not. Go to harbor freight and get a headset magnifying glass tool. It made ALL the difference for me. I have 3 deployed that are mod like this and its suppppper amazing.

@towerviewcams Do you mean this? https://www.harborfreight.com/head-lamp-magnifier-58788.html
Looks like a cool device. Do you do anything special to make sure you don't melt components nearby?
What kind of wire do you use? Do you have a picture of one of the boards by any chance?

my conclusion - when I deploy a new repeater, I take two complete solar / V4 setups. one with LNA and one with LNA bypassed. Install antenna and sweep. then, test the 2 and leave one that has the best overall results. I do this during heavy traffic times at our commercial tower sites so that the noise floor is at its worst.... ether 7am-9am or 3pm-6pm....... Makes ALL the difference for true readings.

[off-topic, but I'm curious]
With v4 taking more TX power, what kind of battery and solar panel are you using? Which antenna do you use?
What kind of tests do you do to decide which one to keep up?

beachmiles · 2026-01-26T03:10:35Z

The test results are really hard to understand. Mixing different antennas just adds another variable making results even harder to determine.
Was the heltec v3 just being use as the TX source then?
These long AI responses are rough.

Here is what I summed up,

The the reg patch def helps RX for most cases. Only saw 1 post saying it didn't help which was prob not what they meant.
The boosted gain being on or off may or may not help. Depends on how much noise is at your location maybe?
Physically bypassing the external LNA could help via resistor and cap removal and jumper wire?

Thank you all for all the work to make this very popular device even better.

jhuebert · 2026-01-26T03:42:30Z

I think this PR is simple and straightforward enough to go with. At this point, I'm just waiting for this PR to be merged and in an official build.

mikecarper · 2026-01-26T06:43:46Z

@towerviewcams do you have a picture of a modified board with the jumper?

spiralshapeturtle · 2026-01-26T06:52:52Z

@towerviewcams do you have a picture of a modified board with the jumper?

#1249 (comment)

The test results are really hard to understand. Mixing different antennas just adds another variable making results even harder to determine. Was the heltec v3 just being use as the TX source then? These long AI responses are rough.

Here is what I summed up,

The the reg patch def helps RX for most cases. Only saw 1 post saying it didn't help which was prob not what they meant.

The boosted gain being on or off may or may not help. Depends on how much noise is at your location maybe?

Physically bypassing the external LNA could help?

Thank you all for all the work to make this very popular device even better.

Yeah your summary is right.

towerviewcams · 2026-01-26T16:46:09Z

@Socalix @spiralshapeturtle @beachmiles @jhuebert Hopfully I didn't miss anyone.

So the PR does NOT disable the 17db preamp LNA. It cannot be bypassed with any firmware for the V4. I have also verified this with Heltec direct. So, the smartest thing to do is to take a V4 with you that has this mod and one that does not. then test at our site. If your in the forest with nothing around, dont waste any time and deploy a V4 stock with the register patch and kick butt. However, if your in a noisy area then you must be prepared with a V4 that has no receiver amplifier if you want to survive and work well.

I dont have a completed photo, they are all in service, plus, my bypass wire was to big. I have ordered PCB jump wire that is the correct wire to use and will upload a photo of that end of this week.

Here is a detailed photo with drawing.

remove R46 (blue one, lower right of GC1109)
remove C72 (brown to left of GC1109 that comes off pin2 of the chip)
install very small PCB jump wire from LEFT solider pad C72 over to RIGHT solider pad of R46

you now have bypassed the receiver amplifier! works amazing!!!!!!!

1337Reaper · 2026-01-26T20:03:12Z

@Socalix @spiralshapeturtle @beachmiles @jhuebert Hopfully I didn't miss anyone.

So the PR does NOT disable the 17db preamp LNA. It cannot be bypassed with any firmware for the V4. I have also verified this with Heltec direct. So, the smartest thing to do is to take a V4 with you that has this mod and one that does not. then test at our site. If your in the forest with nothing around, dont waste any time and deploy a V4 stock with the register patch and kick butt. However, if your in a noisy area then you must be prepared with a V4 that has no receiver amplifier if you want to survive and work well.

I dont have a completed photo, they are all in service, plus, my bypass wire was to big. I have ordered PCB jump wire that is the correct wire to use and will upload a photo of that end of this week.

Here is a detailed photo with drawing.

remove R46 (blue one, lower right of GC1109)

remove C72 (brown to left of GC1109 that comes off pin2 of the chip)

install very small PCB jump wire from LEFT solider pad C72 over to RIGHT solider pad of R46

you now have bypassed the receiver amplifier! works amazing!!!!!!!

Does this cause a drop in total TX strength?

spiralshapeturtle · 2026-01-26T20:48:21Z

@Socalix @spiralshapeturtle @beachmiles @jhuebert Hopfully I didn't miss anyone.

So the PR does NOT disable the 17db preamp LNA. It cannot be bypassed with any firmware for the V4. I have also verified this with Heltec direct. So, the smartest thing to do is to take a V4 with you that has this mod and one that does not. then test at our site. If your in the forest with nothing around, dont waste any time and deploy a V4 stock with the register patch and kick butt. However, if your in a noisy area then you must be prepared with a V4 that has no receiver amplifier if you want to survive and work well.

I dont have a completed photo, they are all in service, plus, my bypass wire was to big. I have ordered PCB jump wire that is the correct wire to use and will upload a photo of that end of this week.

Here is a detailed photo with drawing.

remove R46 (blue one, lower right of GC1109)

remove C72 (brown to left of GC1109 that comes off pin2 of the chip)

install very small PCB jump wire from LEFT solider pad C72 over to RIGHT solider pad of R46

you now have bypassed the receiver amplifier! works amazing!!!!!!!

Would be interesting to see which one outperforms: RAK4631, Heltec V3, Heltec V4 with bypass, Heltec V4 original state with register fix.

If you are in a noisy area, I can't imagine that an outside PCB wire won't pick up any external noise; it's in fact an antenna. If you take a look at the very good RAK4631 receiver, there is a very nice metal shield placed over the components.

Socalix · 2026-01-26T20:50:12Z

Does this cause a drop in total TX strength?

No, it does not. The TX is in a separate path with separate flags.

Old-Dave573 · 2026-01-26T23:26:04Z

@ towerviewcams
Thank you for your work and pictures

beachmiles · 2026-01-27T00:08:16Z

Just flashed the one with boosted gain on and HOLY COW it works great on my repeater!
RX that was previously not happening or getting under 0 db are now like 5db RX. My noise floor is now around -92db but Im still Rxing way better than stock 1.11.
The noise floor right next to this repeater from my T114 companion is -107 to -114db.
Will try the variant with boosted gain off when I get a chance.

mikecarper · 2026-01-27T00:21:31Z

@beachmiles is the improvement with boosted gain ON or boosted gain OFF for you?

beachmiles · 2026-01-27T01:21:41Z

@beachmiles is the improvement with boosted gain ON or boosted gain OFF for you?

I flashed the one with boosted gain on. Will try the other one when I get a chance.

dt267 · 2026-01-27T03:31:59Z

@Socalix @spiralshapeturtle @beachmiles @jhuebert Hopfully I didn't miss anyone.
So the PR does NOT disable the 17db preamp LNA. It cannot be bypassed with any firmware for the V4. I have also verified this with Heltec direct. So, the smartest thing to do is to take a V4 with you that has this mod and one that does not. then test at our site. If your in the forest with nothing around, dont waste any time and deploy a V4 stock with the register patch and kick butt. However, if your in a noisy area then you must be prepared with a V4 that has no receiver amplifier if you want to survive and work well.
I dont have a completed photo, they are all in service, plus, my bypass wire was to big. I have ordered PCB jump wire that is the correct wire to use and will upload a photo of that end of this week.
Here is a detailed photo with drawing.

remove R46 (blue one, lower right of GC1109)

remove C72 (brown to left of GC1109 that comes off pin2 of the chip)

install very small PCB jump wire from LEFT solider pad C72 over to RIGHT solider pad of R46

you now have bypassed the receiver amplifier! works amazing!!!!!!!

Would be interesting to see which one outperforms: RAK4631, Heltec V3, Heltec V4 with bypass, Heltec V4 original state with register fix.

If you are in a noisy area, I can't imagine that an outside PCB wire won't pick up any external noise; it's in fact an antenna. If you take a look at the very good RAK4631 receiver, there is a very nice metal shield placed over the components.

@spiralshapeturtle I put Heltec V3, Heltec V4 original, Heltec V4 bypassed external LNA, and Rak4631 into a noisy area to measure their noise floors with dummy loads on. Heltec V3, Heltec V4 bypassed external LNA, and Rak4631 all have a -118dBm noise floor. Heltec V4 original has a -98dBm noise floor. Do you know what this means?

beachmiles · 2026-01-27T05:34:51Z

Hope to get this mod for a companion firmware!

tpp-at-idx · 2026-01-27T05:41:34Z

Hope to get this mod for a companion firmware!

http://tmp.dreams.sk/public/helv4_semtechpatch_only.bin

for helt v4 bt companion. Semtechpatch with rxboost left on

there is also this http://tmp.dreams.sk/public/helv4_semtechpatch+norxgain.bin whitch is the same but with SX126X_RX_BOOSTED_GAIN turned off

Turn on register 0x8B5 LSB for improved RX, turn off boosted gain

4575800

Socalix mentioned this pull request Jan 14, 2026

🔧 Fix GC1109 FEM LNA being used for Heltec v4 RX #1249

Open

Improve Heltec v4 RX reception with undocumented register patch #1398

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Improve Heltec v4 RX reception with undocumented register patch #1398

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Antenna Swap Test Results - Yesterday vs Today

Test Configuration

Complete Node Detection & Performance Comparison

Utrecht Node (~13.6 km)

Radome West Node (~4.0 km)

PA5B Houten Repeater (7.25 km)

Zeist Slot (0.91 km) - Local Node

loramesh.nl (8.02 km)

Zeist Sanatoriumbos (2.66 km) - Problem Node

Summary Statistics

Node Reach Comparison

Performance Changes After Antenna Swap

V4_2 (boost-packetlog): Better → Standard Antenna

V4 (packetlog): Standard → Better Antenna

Critical Observations

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