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Receive:
Change C435, C431, C619 to .22uF - 400V or higher polyester/mylar or disc

Transmit:
Change C606, C612, C615, C617 to .22uF - 400V or higher polyester/mylar or disc

Transmit and receive:
Change C623 to .22uF - 400V or higher polyester/mylar or disc

This will widen the RX and TX all the way from the mic jack


Direct inject through a .22uF - 400V or higher polyester/mylar or disc straight into pin 9 of V600, leaving the mic gain wide open for proper grid bias.

Thanks Goldfinger. One quick question...can I use polypropylene caps? I have plenty of those in the shack. If it must be polyester let me know and I will get an order together.

Poly is fine. The voltage rating is what's important.
If you are going to inject only and not use a mic, you only need to change the caps after the injection point
(C615, C617 and C623)
The TTC will still work on the injected audio.

I missed a couple on the receive.
C417 and C429 should be changed as well. C429 is on the terminal strip next to the volume pot. the center leg of the pot connects to one end. It's tight in there so I always leave the stock cap and just solder the new one in parallel.

You will still get satisfactory results using a little lower value cap. I just modified one with all .15uF 400V polyester and it still had nice bottom.

Hay gf long time no post

If you want to feed a pin 9 do you leave the connection from V601a intact and just connect to pin 9?

And could you just connect at B38 ??

Connecting at B38 is effectively the same as pin 9 so you could connect there.
If a guy wanted to disconnect the output of V601a to minimize any "noise" from possibly being introduced from previous stages, I would remove C612. Of course this disables the ability of using the mic jack for AM or SSB.

So the input to pin 9 would be line level at this point correct.

yes