Re: Sony ICF-SW7600GR 7.5" Loopstick Mod Completed


Gary DeBock
 

Hello Frank,

Thanks for your intererst in the Sony ICF-SW7600GR 7.5" loopstick
modification. This project was designed (in July of 2008) to provide a
very compact, sensitive SSB spotting receiver for Ultralight radio
TP-chasing on ocean beaches, and was quite successful in this
objective.

A photo of the modified ICF-SW7600GR is posted at
http://www.mediafire.com/i/?kyneobkgsk21n3c . On an Amidon 7.5" Type 61
ferrite bar (available from http://www.amidoncorp.com. for $20 plus
shipping), on a base of J & J 2" waterproof tape (adhesive side out),
wind a center large coil of 120 turns of 40/44 Litz wire (983 uh), and
a separate, single turn of the wire 1/2 inch to the left of the large
center coil. After recording the Litz wire color-coded connections to
the stock loopstick, desolder the connections and carefully remove the
loopstick (which usually needs some "persuasion" because of a serious
amount of glue on the bottom). Install the replacement loopstick on the
frame of your choice, and duplicate the original Litz wire connections
to the new loopstick. You should enjoy a huge boost in sensitivity,
making your tiny ICF-SW7600GR more than competitive with a stock
ICF-2010 on both MW and LW.

My original post on this project (from July 2008) is pasted below
(minus the numerous ??? marks, which may make me seem more confused
than I normally am :-)

73, Gary

-----Original Message-----
From: maxyhopy <fsphotos@...>
To: ultralightdx <ultralightdx@...>
Sent: Sun, Mar 27, 2011 10:58 am
Subject: [ultralightdx] Re: Sony ICF-SW7600GR 7.5" Loopstick Mod
Completed

 
Hello Gary,

I am very interested in modifying my SW7600GR. Could you tell me what
size litz wire you used and also approximately how many turns you used
in modifyoing your Sw7600GR ? Appreciate any help. Frank

Hello Guys,

Although it's a little too large to qualify as an Ultralight
radio, the ICF-SW7600GR provides fairly competent MW performance in a
compact, SSB-capable design. For those MW DXers unable to accommodate
an ICF-2010 for space or financial reasons, this Sony portable would be
perfect as an SSB "spotting receiver" for Ultralight radio transoceanic
targets on an ocean beach... if only it had more sensitivity. Having
had an unused unit sitting around since the Ultralight "Boom" started
late last year (and faced with a situation where a multi-family
vacation would make packing space extremely limited), there was a
sudden compulsion to replace the stock 4.75" x .37" loopstick with a
much more effective Amidon 7.5" x .5" loopstick wound with 40/44 Litz
wire. This MW frequency-optimized combination has provided an
incredible sensitivity increase in the SRF-39FP and Eton E100
Ultralight models (enabling both to receive Australia signals at
Grayland), and I was curious how far it would boost the performance of
this compact SSB portable.

The ICF-SW7600GR has a stock loopstick very similar to that of
the
ICF-2010, in which a fixed larger center coil is mated with a much
smaller tickler coil, used for adjustment of the unit's spurious signal
rejection. As such, the instructions for "supercharging" the ICF-2010
(currently posted in dxer.ca's Ultralight File section) are
electrically applicable to the ICF-SW7600GR, although the lsmaller unit
has a large coil inductance of 983 uh, and the stock loopstick does not
have a snap-out design like the 2010, requiring the hobbyist to use a
moderate amount of effort in separating the glue at the base of the
ferrite bar.

The performance improvement for this $30 modification has
certainly exceeded expectations! When the stock unit was checked
against a stock ICF-2010 prior to modification, it was clearly inferior
in sensitivity on all frequencies. The stock 2010 was far more
effective in digging out weak daytime fringe stations, with or without
the Synch function. After the ICF-SW7600GR received the Amidon 7.5"
loopstick, the situation was completely reversed. The still-compact
SW7600GR now clearly outperforms the stock 2010 on all MW frequencies--
low, middle and high band. High-band performance is particularly
striking, with Synch lock performance on a 1610 TIS station completely
inaudible on the stock 2010. This has been achieved despite a very
modest expenditure for parts (about $20 for the Amidon ferrite bar, and
under $10 for the Litz wire and other items). The modified SW7600GR is
also much smaller and lighter than a stock 2010, providing a very
practical, compact SSB "spotting receiver" for Ultralight TP/TA chasers.

Two pictures of this modified ICF-SW7600GR have been uploaded to
the "ultralightdx" Yahoo Group site, in the "Roll Your Own DXing
Monster" album. It is hoped that various MW DXers will feel motivated
to modify their own ICF-SW7600GR units, and obtain the outstanding MW
performance possible with this model.

73, Gary DeBock

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