[Hallicrafters] Look at this beauty!, cont'd

[Mike Everette]

--- Chris Kepus <ckepus at comcast.net> wrote:

> Does anyone have one of these converters in hand? 
> It would be very helpful
> if someone who does would do a reverse engineering
> of it and create a
> schematic. 


Why would you need to go to all that trouble to
replicate the converter exactly?  

Get out an ARRL handbook from the tube era and look at
the section on receivers.

All that's needed is to build up an oscillator-mixer
to convert the 50 KHz IF signal from the S-76 up to
455 KHz to feed the slicer.  Actually the S-76 IF is
50.5 KHz -- I am saying this w/o consulting the manual
-- so you'd need an oscillator on 505.5 KHz with a
6BE6 or 6SA7 tube if you want to avoid using
three-legged fuses or dead bugs.

I know this will work, as I used a similar scheme once
to convert the 50.5 KHz from an SX-96 up to 500 KHz,
so as to use a surplus IF-tupe RTTY converter with it;
the converter had been originally intended to go with
a Collins R-388.  I also tried the little box with a
different osc frequency to match up another Mil RTTY
converter with a 400 KHz IF input, which had been
intended for use with an RBB or RBC receiver.  This
oscillator wasn't crystal controlled, but for SSB use
you might want to go that distance.

Be sure your oscillator is fully enclosed in its own
box, very well shielded, as in "nothing comes out but
the IF signal."  You should also put RF chokes and
bypasses on the B plus and filament leads if you are
powering it from the radio.  Otherwise you may invite
li'l birdies to sing in your receiver every 505.5 KHz.
    It's no substitute for a crystal calibrator
(something else the S-76 should have).  Been there,
done that, got the shirt.

73

Mike
WA4DLF


 
____________________________________________________________________________________
Have a burning question?  
Go to www.Answers.yahoo.com and get answers from real people who know.