Sony ICF-SW7600GR 7.5" Loopstick Mod Completed


Gary DeBock
 

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 mh, 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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