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Vintage Amateur and Military Radio Amateur/military receivers and transmitters, morse, and any other related vintage comms equipment.

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Old 29th Nov 2009, 6:51 pm   #1
Mikebay
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Default "S" Meter on CR100/B28 Series

Hi Forum,
Does anybody have any info on the above mod?
Any info gratefully received, and any hints. (Even, don't be so stupid!!!)
Mike Bayliff M0XGG
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Old 29th Nov 2009, 7:27 pm   #2
M0FYA Andy
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Default Re: "S" Meter on CR100/B28 Series

Mike,
Please don't go and mash a hole in the front panel for a meter as was the thing to do at one time. There must be twenty CR100s with modified front panels survive for every one unmodified!
Andy
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Old 29th Nov 2009, 7:51 pm   #3
g4aaw pete
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Default Re: "S" Meter on CR100/B28 Series

Hi Mike

Agree with Andy, but if there's already a hole use it !

A better idea is to fit the meter in the speaker housing.
Attached is the circuit I used. Almost any N channel FET will do, the circuit being driven by the AGC line.
Received signals give a forward reading on the meter, after the 500 ohm pot is used to 'zero' it under no-signal conditions.

Regards
Pete
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Old 29th Nov 2009, 8:05 pm   #4
Mikebay
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Default Re: "S" Meter on CR100/B28 Series

I agree with both of you, Andy and Pete, no new holes should be drilled. Mine will probably be external mounted, my pal has one that has been butchered by chrome plating the front panel!
Anyway, many thanks, Pete, for the circuit.
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Old 1st Dec 2009, 8:47 pm   #5
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Default Re: "S" Meter on CR100/B28 Series

Mods, you can close this thread if you like
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Old 1st Dec 2009, 8:54 pm   #6
Sean Williams
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Default Re: "S" Meter on CR100/B28 Series

Pete, that is a very elegant solution, I like it!
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Old 1st Dec 2009, 10:02 pm   #7
g4aaw pete
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Default Re: "S" Meter on CR100/B28 Series

I can't claim ownership of the idea behind the circuit Sean.
I tried a few different s-meter amp circuits, but the one I submitted seemed to give the best results for me.

Also, I'd mention that one of my CR100s had 3 in diam. hole in the panel for a meter when I got it. This I filled by screwing a sheet of aliminium behind it, then leveling the front appperature with decorators' filller. After sanding & spraying, the result is quite convincing !

Regards to all on this great forum
Pete
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