NC38S Still Chirpy At Stock Power????

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From: Jerry Henshaw (jerryh@webzone.net)
Date: Sun Jan 26 1997 - 23:06:37 EST


Hi Gang,

I really have the Midas touch when it comes to building radios...
everything I touch turns to rusty mufflers.

I removed the 5 Watt mod in my NC38S.... still get a bad chirp
with only 300mw!!!

I think I am on to a potential source of the problem.... if you turn the RIT on during transmitt it will pull the transmitt frequency about
1.5khz. I noticed there is about 50mv voltage difference between
the anodes of D301 and D302. The 50mv is enough pull the vxo
1.5khz.

I suspected the RIT circuit might be a source of chirp. Sooo.. I
bypassed the RITcircuit with a clip lead from the main tuning pot
(low side) to ground --- no more chirp!!!! I am considering adding two more transistors to switch D301 and D302 in an out of circuit with the -R and -T signals. I suspect the CMOS inverter used to
generate -R from the -T signal might not drive -R close enough
to ground. I'm getting tired right now. I'll continue the quest
tomorrow and post any positive results.

Has anyone else notice this???

73's

Jerry Henshaw
KR5L / QRP
jerryh@webzone.net

ARCI 9165, QRP-L 847, NORCAL 1999
49er, ARK 20, Wilderness Sierra, (Soon 38 Special)


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