[Hammarlund] Possible mods - HQ-110

[Ross Stenberg]

If you want to stick with the front end of a boatanchor spend $22 for a 
soft rock IF and let your computer do all the subsequent signal 
processing. http://amfone.net/Amforum/index.php?topic=24547.0
http://kb9yig.com/

     73 Ross K9COX

On 7/9/2011 12:16 PM, Kenneth G. Gordon wrote:
> After reviewing the circuit diagram of my HQ-110C, I have arrived at
> the following tentative mods.
>
> 1) Replace V6 6AZ8 2nd IF tube socket with 7 pin socket, or build
> 9pin to 7pin adapter.
>
> 2) Rewire 2nd IF stage to straight 6BA6 IF stage as nearly identical
> with 1st IF stage as practicable. This eliminates that marginally
> working "power detector" (and BFO) for CW/SSB and provides the same
> level of IF selectivity for CW/SSB as for AM, yet retains the
> original "S" meter functionality, adding its usefullness for CW/SSB.
>
> 3) Eliminate 6BJ7 triple-diode, replacing with solid-state diodes,
> possibly hot-carrier diodes, mounted on terminal strips. This retains
> all original functions, including AM detection and both original AGC
> circuits, yet provides a "free" socket for the next mod.
>
> 4) Rewire 6BJ7 socket for a high-transconductance dual triode (6ES8?,
> 12AT7?) for a) BFO, and b) triode product detector. One effect of
> doing this is that it separates the BFO from being in such close
> proximity to the 2nd IF (originally in the same tube and tube
> socket), and should reduce or eliminate the BFO signal from effecting
> the AGC circuit, which was the main reason one could not use AGC or
> the "S" meter when in CW/SSB mode.
>
> 5) Rewire mode switch to receive CW/SSB audio from PD (this is a very
> simple change, requiring the re-routing of one wire).
>
> 6) Adjust time constants of AGC circuitry for "fast" and "slow",
> possibly using the "MAN/AVC" switch. This prevents having to drill a
> new hole and mount a new switch.
>
> These mods should provide no external changes, and require no new
> socket holes, but should make what I consider to be a fairly decent
> receiver into a better performer for CW/SSB.
>
> Your thoughts?
>
> Ken W7EKB
>