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is this worth building


nomadradio

Analog Retentive
Apr 3, 2005
5,672
8,442
573
Louisville, KY
www.nomadradio.com
Only if you lay it out to keep the input and output sides separated. If the radio you're using has sideband, it should have a place to unplug the final transistor for measuring final current. Pull it out and you'll now have a far weaker receive signal from the radio. Pull the bias-test jumper from the driver as well, and you'll have a really weak signal to work with. There won't be any modulation with both bias-test jumpers pulled out, just a carrier.

73
 

unit_399

EL CAPO
Jun 17, 2008
1,698
1,698
173
ALEJANDRIA, COLOMBIA SA
Iiwilly -

I have used one of these things for decades. Not what you would call "hi-tech" test gear, but does the job well for what it is. I always feed a prerecorded audio track into the test radio. Just listening, while not hearing yourself speak, is more effective.
- 399
 

1iwilly

Well-Known Member
Dec 7, 2008
563
335
73
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Iiwilly -

I have used one of these things for decades. Not what you would call "hi-tech" test gear, but does the job well for what it is. I always feed a prerecorded audio track into the test radio. Just listening, while not hearing yourself speak, is more effective.
- 399
i have another radio on a dummy load that i use to monitor modulation i must have the wrong headphones I'm just looking to tell when the mod is low and then high after a tune-up
 
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guitar_199

Sr. Member
Mar 8, 2011
715
959
103
Deer Park, TX
Well I'll put it this way.....
With a few calculations... and a bell and whistle or 3 added....
As long as you check with a freq counter.....
This could be a fair "poor man's RF generator for receive alignments and such...
It would never be a lab instrument.... but hey.....

"The warrior uses what is at hand"!!!!!!!!


I would think of adding a rotary switch.... OR a pair of screw down banana jacks...
so I could switch dropping resistors.....calculate the dB attenuation.....
ad you could make your bench radio drop to any level you need.
Again, not bench quality.... but if "you don't tell.... I won't tell!!!!"
Build a little integrated circuit audio oscillator to plug into the mic jack on the bench radio...and now you AT LEAST have AM modulation.....
 

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