[Premium-Rx] HF-2050

Tue May 22 09:28:28 EDT 2007

Sorry to have gotten into this thread a bit late.  The last time my
power supply failed I chose to replace it with a small switching supply.
It cost about $50 and seems to work very well - at least it is much
cooler.  It is about 25% the size and weight of the original.

Ed, W9EJB

-----Original Message-----
From: premium-rx-bounces at mailman.qth.net
[mailto:premium-rx-bounces at mailman.qth.net] On Behalf Of Jan Skirrow
Sent: Monday, April 23, 2007 1:36 PM
To: Bill Johnston
Cc: premium-rx at mailman.qth.net
Subject: Re: [Premium-Rx] HF-2050

Hi Bill...

I can't add much to what Walt told you. I've worked on Walt's HF2050s 
and heat problems and/or connector problems are at the root of most 
problems you're likely to be able to fix. It is not an easy radio to 
work on and too many parts are proprietary and not obtainable at any
price!

The radio apparently was intended to be used with fairly high volume 
forced air cooling directed through the power supply and main radio 
compartments in an enclosed rack cabinet. Without that, it will make a 
pretty good BBQ. Military techs here who worked on it considered heat 
the major source of problems. It isn't just convection that's the 
problem, the PS heats the entire radio by conduction as well, so cooling

has to be fairly comprehensive.

Walt took a series of temp measurements with various fan arrangements, 
and was able to get the temp down to the point where it was tolerable. 
Being an old radio, keeping it on the cool side is very important.

The most extreme thing I did with one of Walt's radios was to perform an

PSectomy - I removed the power supply, made a short connecting cable 
(it's a standard connector type) and operated it this way without 
modification to the radio so that the change could be easily reversed. 
The PS was mounted on a separate 5.25" x 19" panel attached to the back 
of the rack cabinet Walt uses for his radios. The PS stayed at a 
tolerable temp (a modest fan would remove most of the heat when the PS 
is in fairly open space and oriented for max air flow). The radio 
compartment was still warmish from the heat normally generated by the 
kind of ICs Collins used, but much less than with the PS mounted in the 
same case.

We ran some checks on this configuration and could see no discernible 
effect on radio performance.

The project was documented, and there is a link on the Premium-Rx 
website on one of the reference pages.

It is one of the mysteries of this radio - it was state of the art at 
the time it was built (maybe that should be state of the Art!) and yet 
had an off the shelf power supply that should have been seen as a bad 
choice for the kind of reliable operation the military requires under 
difficult conditions. I don't think we've ever found anyone who actually

worked on the design, so this mystery remains!

The HF2050 never became a commercial success beyond the military order 
that led to its development. However, it was offered under that 
designation as part of the Collins 8050 series for a time (somewhere I 
have a photocopy of an 8050 brochure showing it). I don't know if any 
were sold as part of an 8050 setup and assume that later receivers in 
that very successful series were based on the 2050 design. But this too 
remains speculation!!

73, Jan

Bill Johnston wrote:
> HELLO:  I have an HF-2050 and love the receiver...when it works.  It
always starts well, but then after awhile I get the default light.  It
is a Debug 2=0001.H, Debug 3=0048.H, Debug 4=0000.H.  Think it is in the
48 volt loop in the synth.  Where I go from here??  Tnx  Bill
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