UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - 2nd November

Techman · 28th Nov 2022, 6:55 pm

I've tested the Fidelity mic on the Fidelity 1000 and at first it didn't work as it had obviously been wired for a different radio - I think it just keyed it on to transmit as soon as it was plugged in and a quick plug into a Cybernet radio proved it had been wired to work on one of those sets. It looks like the next Fidelity radio in the series is the 2000, a Cybernet chassis radio, but this model doesn't use this style of microphone. The next Fidelity set is the 3000 base station model, which is another user of the 'Great' made chassis, similar, but not the same as the one used in the 1000 model. This 3000 model base station again uses the same style mic as the 1000 model, so the mic could have come from one of these, although the chap did say that it had come from a 1000. I think the bit that had probably been forgotten was that on the demise, or whatever, of the original 1000 radio, the mic had been re-used with another radio and wired accordingly, perhaps when the end of the cable was shortened.

I rewired the mic plug to the Fidelity 1000 standard and the microphone worked. Using another radio as a monitor I compared the Fidelity with Sharman's microphone and it sounded about the same as far as I could tell, although I thought that perhaps I could detect some small difference. I've since had a radio check with someone using both microphones and they said they sounded about the same - 'about' perhaps meaning that there was some difference, but probably nothing worth bothering about, so it sounds like the insert is still good.

Out of interest I measured the DC resistance of both microphone inserts from the plug when in TX and the Fidelity measured around 390 ohms, the Sharmans measured just over 450 ohms. I then measured a couple of other hand mics of both styles and an old Sharmans mic of the same style as the Fidelity measured just over 500 ohms and a more recent CRT coffin style mic measured around 460 ohms. The newer Sharman's and CRT mics, which are of the 'coffin' style measured within 10 ohms of each other. The older mics being the original Fidelity and the old Sharman's, both of the same case style measured over 110 ohms apart. I don't know what we can deduce from this, probably nothing. So the good news is that we have an original Fidelity badged microphone that appears to work well.

28th Nov 2022, 6:55 pm	#103
Techman Dekatron Join Date: Nov 2009 Location: Lincolnshire, UK. Posts: 5,000	Re: 2nd November - UK CB anniversary I've tested the Fidelity mic on the Fidelity 1000 and at first it didn't work as it had obviously been wired for a different radio - I think it just keyed it on to transmit as soon as it was plugged in and a quick plug into a Cybernet radio proved it had been wired to work on one of those sets. It looks like the next Fidelity radio in the series is the 2000, a Cybernet chassis radio, but this model doesn't use this style of microphone. The next Fidelity set is the 3000 base station model, which is another user of the 'Great' made chassis, similar, but not the same as the one used in the 1000 model. This 3000 model base station again uses the same style mic as the 1000 model, so the mic could have come from one of these, although the chap did say that it had come from a 1000. I think the bit that had probably been forgotten was that on the demise, or whatever, of the original 1000 radio, the mic had been re-used with another radio and wired accordingly, perhaps when the end of the cable was shortened. I rewired the mic plug to the Fidelity 1000 standard and the microphone worked. Using another radio as a monitor I compared the Fidelity with Sharman's microphone and it sounded about the same as far as I could tell, although I thought that perhaps I could detect some small difference. I've since had a radio check with someone using both microphones and they said they sounded about the same - 'about' perhaps meaning that there was some difference, but probably nothing worth bothering about, so it sounds like the insert is still good. Out of interest I measured the DC resistance of both microphone inserts from the plug when in TX and the Fidelity measured around 390 ohms, the Sharmans measured just over 450 ohms. I then measured a couple of other hand mics of both styles and an old Sharmans mic of the same style as the Fidelity measured just over 500 ohms and a more recent CRT coffin style mic measured around 460 ohms. The newer Sharman's and CRT mics, which are of the 'coffin' style measured within 10 ohms of each other. The older mics being the original Fidelity and the old Sharman's, both of the same case style measured over 110 ohms apart. I don't know what we can deduce from this, probably nothing. So the good news is that we have an original Fidelity badged microphone that appears to work well.