CB Mic wiring for UK FM radios 

Right that does it! I've been meaning to make a mic wiring jig for 38 years. I'll get Mr Chippie to make one on a video....he should get back here after his Christmas trip back home this evening. We've got a small vice but rarely use it for wiring mikes. Richard, G0OJF, UK

@@ukfmcbradioservicingTango21 Look forward to watching 🤣 might give me inspiration

Glad it was helpful! Richard

They do wire the same & yes the variable volume control affects the output level. Sometimes power mikes have more wires so they work with old American valved sets with relay switching. I accept that some people like to use a base station microphone with a base station. My objection (other than echoes) is that UK FM radios all incorporate speech processing circuits & usually sound their best with a standard microphone. If you add pre-amplification with a power mic, the speech processing in the radio can end up adding distortion. Back to the USA AM system. speech processing wasn't part of the type approval & getting modulation clear & closest to 95% modulation helps with clarity & thus range. On an FM system range isn't affected by the audio...unless it's muffled. Therefore the whole accessory mic market is aimed at the USA or other AM CB markets. On the post 2014 CE approved radios that have come here & are useable legally on AM (on the CEPT 40 channels), they all have speech processing because they are AM/FM, thus making power mics pointless. Richard, G0OJF, UK

Hello James, this link will take you to the correct magazine. worldradiohistory.com/Archive-CB-Radio/Citizens-Band/CB-Citizens-Band-1988-10.pdf Richard

It's a snag which is being rectified. When I had a new video mixer a few months ago, the monitor output is HDMI; I was previously using Sony Broadcast kit, but youtube didn't recognise the HiBand format & compressed the hell out of everything to 320p. So with the new mixer I can't use the mega quality sony CRT monitors, so had to buy a flat screen one that accepts an HDMI input.........but the flat screen doesn't have sufficient viewing angle to be seen from my seating position at the bench. I have therefore ordered a small HDMI monitor to put on the bench to overcome the problem. The monitor arrived yesterday but I'm still waiting for an interconnecting cable to arrive. Richard

So I looked at the circuit. Correct 1= Audio 2= Gnd 3= TX. The radio uses a relay to switch between TX & RX, so no RX connection to the mic is required. Incidentally, pin 5 is power out to a mic that requires a power supply such as a K40. This means the radio receives with no mike connected. Richard

@@ukfmcbradioservicingTango21 Thanks for your quick reply...so I can just stick some shrink tubing over the end of the RX wire and not connect ? All the best and have a nice Christmas. Steve. 🥂

@@stevelomas4119 Roger on that. Richard

I'm sorry Ryan but I can't help at all. Quite a few business radios we service use those kind of modular plugs. We either repair the mike with the set & if it's the lead that's duff or no mike at all we would then either buy a new factory mike or a new cheaper pretend mike depending on what the customer wants. I haven't ever owned any Kenwood/Icom/Yaesu amateur radio gear & we don't normally do repairs to amateur radio equipment either, so I just don't see radios like yours. Whichever wire carries the mic audio will have to be the screened one. If the lead you are using isn't screened..such as a telephone type lead, you would lose the audio in the lead & end up with just a hum, I would expecr. Richard, G0OJF, UK

Maybe thats why im getting no audio out. I was using just standard wire not screened for testing purpose.

You have to work out if it's the radio or microphone at fault first, so try another mike. If it's the microphone, then that sort of noise is a) the mike lead or b) dirty switch. It's easiest to use a switch cleaner first. If you are in the UK, the Servisol one is the market leader. Richard, G0OJF, UK