[Hallicrafters] SX-71 Reconstruction completed

[Philip Atchley]

Hello all
Well, I'm pleased to be able to say that the reconstruction of this SX-71 is
finally completed and it is burning in prior to the final alignment and
cabinet installation.

I say "Reconstruction" as this overhaul went far beyond the usual re-cap and
refurb! (It needed it).

When this set arrived it played (barely) as I was able to hear the local
blockbuster BCB poorly stations with 6 feet of wire at about S3 or less.
Could hear some of the stronger SW broadcast stations with an antenna.  It
was noisy and a little erratic.

Now, with no antenna (out of the case) the local stations come in at S7 and
peg the meter with 6 feet of wire.   With an antenna the dial is "wall to
wall" with stations and with no antenna it is nice and quiet with no pops or
crackles.

Here is what was done to it.  There was probably more done but this is what
I remember.  The only thing not done to date is the dial cord restringing
(which looks good).  I was going to do it before re-assembly, but wanted to
get the set "together" by this evening as there is another large "project"
due to arrive tomorrow for a friend and I don't have the room to have more
than one project "in work" at any given time.  (the dial cord hasn't arrived
yet).  I expect these cords will hold up till I can get back to it.

Chassis work:
1.  De-rusted the chassis.  Replaced the rusted tube shields.
2.  Replaced 16 capacitors with Orange drops PLUS the electrolytics with
axial caps under chassis.
3.  Replaced 33 carbon resistors, at least 70% of which were WAY out of
tolerance (some more than double nominal value).
3.  Replaced all tubes except 5Y3 & 0D3 (for which I have spares).  Many of
the tubes were original Halli tubes, most tested weak.  (I was fortunate in
getting some good buys on tubes at the Livermore Swap)
4.  Replaced power cord with polarized 2 wire cord so that chassis bypass
cap is always on the neutral lead.
5.  Replaced all 3 toggle switches as two had erratic contacts.  I used the
old style bat handle switches from Radio shack as they "nearly" look
original.
6.  Used DeOxit D5 to clean all controls, switches, tuning cap fingers etc.
Re-positioned one band switch wafer to eliminate "extreme" binding in the
band switch (With that long shaft wafer alignment is important).  Switch now
smooth and easy.
7.  Used De-Oxit D5 on the tube socket pins.
8.  Did a preliminary alignment of the set .

Cosmetic Work (most posted here previously):
1.  Cleaned, stripped, sanded, painted and clearcoated lid.
2.  Sanded and painted and clearcoated main cabinet.
3.  Replaced front panel with one in better condition.
4.  Cleaned the main and banspread tuning dials (which needed it badly)
5.  Burnished the aluminium skirts on the knobs with felt wheel on Dremel.
6.  Replaced the two tuning knobs, one of which was badly chipped.
7.  Replaced the rusted screws in the cabinet parts.

Still to do:
1.  Final alignment this afternoon (after several hour burn-in).
2.  Install in cabinet.

73 de Phil  KO6BB
Loving home provided for wayward Boatanchor Receivers
k06bb at elite.net
Merced, Central California
37.18N  120.29W  CM97sh







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