Recap SP-600

[Dave Franklin]

I just finished recapping my JX-7 this weekend.  It was quite an
undertaking though I must admit that it was well worth the effort.  The
"black beauties" lived up to their reputation in my radio.  There were
13 / .022 mfd and 35 / .01 mfd.  All of them were split or cracked.  The
capacitance value measured OK but they were all leaking.

I did it in sections, testing after each, as recommended in the Hi Res
video.  This way, if problems occur it is much easier to isolate them.
I did have one problem, an intermittent ground connection on the second
RF stage.  Odd as it may seem, it was not one of the grounds that a
capacitor was tied to.  It had been there for almost 50 years and not
caused a problem until it was disturbed by removing the RF assembly. Go
figure!

I used Orange Drops in the audio and 455kHz IF stages and ceramic disks
in the HF oscillator, RF section and the turret assembly.  I changed out
two .25 mfd and a .05 mfd with Orange Drops.  There are a number of
bathtub capacitors that test good.  Will probably change them out
later.  Also have tubular electrolytics to replace the filter capacitor
but would rather replace the can if one is available.  If anyone out
there knows where I can get a new 3 X 20 450V can, please Email me.

After changing the caps and realignment the radio sensitivity is good.
1 micro volt or less on band 1-5 and 2.6 micro volt on band 6.  The
performance is greatly improved, especially on the higher bands.  Put
her back in the case for now and am going to start on another radio.
Future projects include, HQ-140, HQ-170, HQ-180, NC-173 and a Howard
437A.

Thanks to all of you on these lists who keep our noble hobby alive.

Dave Franklin
Cornelius, NC

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