Topband: Good Receivers for Top Band

[K3BU@aol.com]

K5PC wrote:

>I have heard for years about  how good "tricked-up" Drake receivers are.
>Nearly every picture of "Top-Gun" ham shacks feature one.
>This sent me on a one year search and study on the subject.

I think one really good one is being overlooked - R4B.

R4B has only one mixer at first IF level. I modified mine by putting narrow 
filter (SSB or CW) instead of the 8 kHz roofing filter. (One filter, less 
ringing with static crashes). Second selectivity stage is done at low IF with 
LC circuits.
I replaced the preselector tube with EF183 (6EH7?) which added some gain up 
front when needed (beverages, 10m) and I separated the RF gain control 
(controls only preselector) from IF gain control (rest of the stages, AVC). 
It allows to set the IF gain just at the treshhold of internal IF noise, 
while RF gain is used to set the gain just at the treshhold of the band 
noise.  It also helps to do the alignment every so often, tube radios like to 
drift. I am looking forward to K4ZS mod kit for R4B, it should make it even 
better (ultimate?)

Yuri, K3BU, VE3BMV



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