[R-390] SSB adaptors-R-390

[pete williams]

G'day list..
One  swallow  doesn't make  a  summer, but looking over the flock that flew around a 
few years back, -one bird with potential stood out in my  evaluation of  SSB 
adaptors. I settled on  the details of the box written up in ER by Mike  Bohne 
KG7TR--- sorry I  don't  have the  issue  date as paper  work I  have didn't  show 
it. .
It is a 6BE6  prod. det, but its great performance on my subjective  evaluation lies 
in the way AGC is  derived, the efficient selectable  hang time,  and the levelling 
ability of the  audio which is  fed back into the    R-390A. I would say that a  read 
of the  technical  details would  clarify some of the  AGC problems  that have been 
aired recently.
 The  fact that NO mods  are made to the  rx is  a plus  but 4 tubes  and  attendant 
P/S make  for  a sizable package.-- so what--- so's the  receiver !.I used a  spare 
BFO from a R-390A as the injection oscillator which is  easily reset for  LSB or USB 
as the  fancy takes  you and with  what ever filter bandwidth you select. Input is 
via  the  455 khz output on the  back panel. Mike  makes the  comment in his piece 
that the  RFgain system works just like the ones used on most Collins  and Drake 
xcvrs.
As a side issue I  found that putting the  P/S xfmr in the same box as the  PTO cause 
FMing of the  detected  signal which I attributed to magnetic  field  from the xfmr 
influencing  the permeability characteristic in the  PTO.... probably  no effect with 
a more  conventional L/C circuit which Mike used.
Like I said, it's the only  aadaptor I've ever used yet appears  eqivalent in 
performance to any I used in ham gear over years.
I commend the  article and adaptor which I currently use . Someone on the list might 
have a reference to the issue number  for those who dare !
Cheers

Pete D..Williams VK3IZ
METUNG, 3904
AUSTRALIA
jupete at bigpond.net.au