Re: [IRCA] IRCA Digest, Vol 51, Issue 42

[satya@xxxxxxxxxxxx]

Hey Dennis:

I seem to remember Gary mentioning that his 7600GR was a disappointment as
well.  Perhaps the same alignment QA process (or lack thereof) is used by
Sony on the 7600GR as the SRF-59, so you never know what you're going to
get?  My 7600GR is actually a pretty darn good receiver, so perhaps I won
the QA lottery!

Once Gary gets it tuned up on a monster ferrite, I'm interested in seeing
how the images are, since during the day mine has a few that sound like
strong locals.

73 - Kevin S
Bainbridge Island, WA


> I'll be interested in how this turns out. To me the ICF-SW7600GR is a
> major
> disappointment. I only use it when I need the synchronous detection and
> I'm
> too lazy to go get the ICF-2010, which I don't leave laying around. It
> lives
> in a protective case; there's no way I could afford to get it fixed or
> find
> another one.
>
> 73
>
> ----- Original Message -----
>> Date: Tue, 15 Jul 2008 16:08:19 EDT
>> From: D1028Gary@xxxxxxx
>> Subject: [IRCA] Sony ICF-SW7600GR Hot-Rodding
>> To: irca@xxxxxxxxxxxxxxxx
>
>> Hello All,
>>
>> After several requests to develop an alignment  system for the popular,
>> compact Sony ICF-SW7600GR portable, I finally decided to  dig in to the
>> circuitry, and investigate the stock loopstick thoroughly.   Perhaps the
>> fact that
>> an upcoming family vacation (during which our compact  vehicle would not
>> accommodate the 30" or 19" loopstick modified  ICF-2010's) had something
>> to do with
>> my motivation.
>>
>>     The SW7600GR loopstick is in fact a smaller  version of that used in
>> the
>> ICF-2010, i.e. a large, fixed center coil and a much  smaller end coil,
>> used
>> (in Sony's design) for adjusting the spurious signal  rejection of the
>> loopstick. Like the ICF-2010 system,  there is no way to  align the
>> fixed
>> coils on
>> this antenna.  The only way to significantly  improve AM-DX performance
>> is
>> to
>> remove the entire 4 3/4" x 3/8" stock loopstick,  and replace it with a
>> longer
>> externally-mounted looptick having comparable  coil inductances.
>> Fortunately,
>> the ICF-2010 "Supercharging" file (currently  posted in dxer.ca's
>> Ultralight
>> File section) tells exactly how to accomplish  this, in an electrical
>> manner.
>>
>>     For the ICF-SW7600GR, a hobbyist will need to  measure the stock
>> inductances of the two coils, and either recycle the stock  loopstick in
>> a
>> larger
>> composite bar augmented by blank 3/8" ferrite bars on the  ends, or
>> create
>> a
>> self-wound loopstick on 1/2" diameter Amidon ferrite bars (my  probable
>> choice).
>> Practically speaking, the external loopstick should be  limited to a
>> length of
>> about 15", since it is unlikely that this hot-rodded  SW7600GR would
>> have
>> a
>> performance surpassing that of a hot-rodded ICF-2010, even  with a
>> longer
>> loopstick.
>>
>>     It will be interesting to see how this  "supercharged" ICF-SW7600GR
>> performs in the real world.  Although not  really close to being an
>> "Ultralight"
>> radio, it might be useful as a barebones  SSB "spotting receiver" for
>> those
>> travelers unable to accommodate a more capable  SSB unit.
>>
>> 73, Gary DeBock
>
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