[R-390] THE R390A Audio Transformer ! Do You Have One?

[chuck.rippel at cox.net]

Most know about this but just in case.

I was having a conversation with the late Fred Hammond some years ago. 
During the conversation the subject of 600-8/4 ohm audio transformers 
came up and how hard they were to find.  Fred
was not aware of the difficulty finding them and mentioned he had a 
personal design used when they were building Collins 75A-4's in Canada 
back in the day.  Fred said, let us wind a few, I'll send you a couple 
and let
me know what you think.

Wow !  The transformer is good for 12 watts (approx 24X the R390A's 
rated audio output, you won't saturate it) and is flat from something 
like... 30-20,000 cps.  It just sounds great !  In passing the feedback 
to Fred, the subject of price came up.  Cringing, I waited for his 
answer.  "How about about $17 bucks,"  would that sell?

Heck yes !  So, Fred put it in Hammonds transformer line.

That transformer is still available and works great with R390A's.  Its 
gone up to $26.20 over the years; Antique Radio sells it: 
http://www.tubesandmore.com/


Model P-T119DA

Transformer - Audio Interstage, Hammond, 12 Watt
Developed in response to requests from the "Collins Collectors 
Association," this is a matching audio transformer for older equipment 
with 600 ohm audio output, driving modern speakers.

Or for "classic" high impedance speakers used with newer equipment, 
simply swap primary for secondary (ie...4 or 8 ohm input and 600 ohms 
out).

Key Features Isolation unit: (i.e. seperate primary and secondary)
Primary: 600 Ohm (with 6" wire leads)
Secondary: 8 Ohm with 4 Ohm center tap (with solder lugs)
Power: Rated at 12 watts
Frequency Response: 30 Hz - 20 kHz
Weight: 1.3 lbs.
Mounting: 2 hole u-bracket mount - on 2-3/16" mounting centers.


There 'ya go.

Chuck Rippel