[Collins] KWM2A repair question

[Jim Brannigan]

This might help:
Bill Orr, in a 9/1979 HR article.
Receiver blocking due to screen emission from the 6146's.
Cure:
A 1N4005 diode in series with the screen power lead.  Replace wire from
screen feedthrough to tiepoint (TS1) pin 4, with the diode (cathode towards
tie point)
This places the diode before and in series with R 148 (820 ohms)

Jim



> Hello;
>      I am reparing a 1969 RE KWM2A for a local ham here in Korea. It had
PTO problem but it is settled thanks to your advices. It is all aligned as
instructed in the manual. I still have two more things as below.
> (A) S 9 indication on the s-meter means what microvolt signal at the
antenna input? I need to set this with RX Gain Adj and S-meter Zero knobs.
> (B) When the radio returns to receive from transmit, a loud audio squeal
occurs from the radio speaker for about two seconds. Reducing any of the Mic
Gain or AF Gain or RF Gain eliminates the squeal. I am aware that the R122,
47K 2W resistor supposed to cut off the feedback path but the squeal still
occurs. I tried decreasing R122 to 25K but this only reduced the squeal, not
eliminated it.
>       Any advice on these? Thanks in advance.
>
> Yong Surk Lee,Ph.D
> Professor of Electrical & Electronic Engineering
> Department, Yonsei University, Seoul, Korea
> Ham; WW6N & HL1FB, Director of Korean Amateur Radio
> League in charge of international affairs,
> Former head of KARL Laboratory
> Email ; yonglee@yonsei.ac.kr
> Homepage; http://mpu.yonsei.ac.kr
> Phone; 02-392-7194 Cellular; 017-236-2872
> Fax; 02-312-4584
>
>
>
>
>
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