[hiro, JJ1FXF]

Graham,

What I meant to say "my 9R-59D was poor receiving sensitivity" had actually two issues.

One, relating to my original question here, is when connecting my dipole antenna of Ham radio to the added SO239 connector, the voltage after 2nd IF (AGC D2 1N60 cathode side) will be at 20% than connecting only center of it.

Yes, it should be like that bcoz RF coils are autotransformers and DP antenna is not good for that, I understood.

Second is that the voltage of ACG (D2 Anode side) is getting gradually weaken to 0V, sometimes 30min after switch ON or sometimes within 5min.

I thought the diode D2 was deteriorated, but it seemed to be working well and the input from the 2nd IF to the diode is actually gradually getting down as time goes.

I am investigating on this second issue now.

BTW, I got a TX-88D which is the AM/CW transmitter of the same era of 9R-59D. It really looks COOOOL! Not switched ON yet bcoz I don't have its xtal.

I'm planning to build a DDS VFO for this TX88D and hope to be on the air soon.