[R-390] R390A and the Q-multiplier

[Tisha Hayes]

I have been following the recent discussions regarding topics like
stagger-tuning the IF and now with a mention of the Q-multiplier I decided
to add a comment;

For a while I paired up a Central Electronics model B sideband slicer with
a DQ Q-multiplier to a EAC R-390A. Most of my receiving work has been with
narrowband CW or SSB, I seldom do anything with SWL or BCB listening so 16
KHz BW really is not that interesting, but I liked to park on a frequency
(like HF aviation channels) for days at a time. I found the model B/DQ
combination to be fiddly to work with and required babysitting to keep
things working properly.

What I ended up doing was to series tune the IF stages, add a 10 KHz
roofing filter between the RF and IF decks and to replace the 16 KHz filter
with a 12 KHz filter that I found entirely by accident. Even so, I seldom
used the 16 or the 12 KHz setting but sometimes I would use the 8 KHz
filter for listening to ESSB operators. In my second R-390A I have the rare
ceramic filter variant IF deck and it is less harsh to listen to but the
filter shapes are not as good.

Maybe on a pure R390 (non A) with the LC filters then a stable Q multiplier
would be an interesting combination. The Central Electronics stuff was too
quirky to keep going for reliable performance. For SSB I use a Hammarlund
HC-10 but I also have a CV-591A that I played with for a while and I still
could if I need to heat up the entire house with all of the tube filaments
glowing at once. The CV-591A is in serious need of re-capping so mostly it
is shelved.

*Ms. Tisha Hayes, AA4HA*