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#20 Kenwood TM 621A deaf 220 MHZ Receive

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Radio Tech:
#20 Kenwood TM 621A deaf 220 MHZ Receive

In this video I attempt  to repair the 220 MHz receiver in a 621a. I have no service information on this rig but have repaired several of them. There are no free copies of the service manual online that I can find. I use the TM-721 block diagram to trouble shoot. The 721 is a 2 meter 70 center meter unit.

vk6zgo:
I guessed it would be the dual-gate FET in the receiver input.

I had the same thing happen with an IC251A.
Nice thing about them is they output a "sniff" of the 10.7MHz IF,so I could hang a HF Rx on that,& eliminate all of the IF onwards.

Radio Tech:

--- Quote from: vk6zgo on December 20, 2015, 04:19:06 am ---I guessed it would be the dual-gate FET in the receiver input.

I had the same thing happen with an IC251A.
Nice thing about them is they output a "sniff" of the 10.7MHz IF,so I could hang a HF Rx on that,& eliminate all of the IF onwards.

--- End quote ---

From data sheet
3SK184 GAAS N-channel MES FET UHF
Low Noise Amplifier 3RR - SMD Case: SOT-1

I have no idea what the original is. But this is what Clif Holland from Avidd told me to use a while back. They seem to hold up fine.
Good idea about sniffing the 10.7. One of the reasons I like to keep a small HF rig on the bench.
They become test gear :)
Thanks for sharing

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