Use this list when an SR-955HPC (V1, V2, or HPC+) will not transmit, will not key, or “won’t modulate” on AM. Work top to bottom. If the meter shows SWR HI (or HI SWR) when you key, start at step 4. The 955 does not show E4; E4 is the 447HPC2.
Confirm the generation first: Which 955 do I have?
1. Mode and band
- Set the radio to AM if you are trying to talk AM. USB/LSB will not sound like AM modulation to a CB listener.
- Pick a channel or frequency you are allowed to use. The 955 is a 10/12 meter radio, not a CB. Does the 955 have all the AM channels that 497 does?
2. Microphone
- Hold the mic with the grill toward your mouth and press PTT (the side button) for the whole sentence.
- Try a known-good Stryker-compatible mic if you have one. What microphones are compatible with your radios?
- There is no AM mic-gain item in the customer menu. Do not open the radio to turn internal modulation pots unless a technician asked you to. Where is the mic gain control?
3. Power and talkback
- Turn RF power / variable power up from minimum. From the factory that knob sets dead-key and PEP. Does the variable power just set the dead key?
- Turn talkback up and key. If you hear yourself, the radio is keying. How do I hear myself with talkback on the SR-655HPC or SR-955HPC?
- Watch the display on key-up. TX indicator should come on. A big voltage drop on key is a power-wire / vehicle issue, not the mic. When I transmit the display shows my voltage drops
4. Antenna, coax, and SWR HI
- SWR HI on the meter (and usually a beep) means high SWR. The radio stopped TX on purpose. Check the antenna, mount, and coax. Full write-up: Radio shows SWR HI When you key the microphone to transmit. The 955 does not display E4 — that code is the 447HPC2.
- Try a known-good coax. A shorted or loose PL-259 is a common “no TX / SWR HI” cause. To tune a new antenna you may need to turn TSR off in the function menu, then turn it back on: High SWR shutdown - How to Temporarily Turn it Off.
- If another radio works on the same antenna and the 955 does not, skip to step 6.
5. Version 1 only — connectors
On a full-size case with no vents (V1), a loose front-board jumper/connector can kill audio or talkback and is worth checking before an RMA. Follow Low Speaker Volume or Low Talkback Even With Control Set to Max (V1 only). Do not solder extra jumper wires unless support asked you to.
6. Still dead — send it in
If AM is selected, the mic keys, the meter is not showing SWR HI, voltage holds, and V1 connectors are seated, request an RMA: repairs.strykerradios.com.
Related: Programming the SR-955HPC if the problem only appears after a software write.
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