[Hallicrafters] Re: SX-71 Poor BCB, etc.

[Al Parker]

Hi Phil, Barry & all,
    1st, Phil, I knew you had been into BA's b4, we've corresponded a few
times, I think, so had tongue in cheek earlier when I suggested a "real" BA.
(FWIW, I think the SX-101's are the prettiest rcvrs made).  Also I guess
I've been disenchanted with the SX-71.  I had one, bought at a very low
price, kinda cruddy, knew it needed work.  Thought it oughta be a decent
rcvr, even compared it's under-chassis construction with the SX-28 (see my
webpage).
    It had antenna coil problems similar to those reported now by several
people.  I think 3 or 4 bands had the primary winding open.  I suspected
lightning, transmitting into the ant connector, etc.  Maybe the AC line
bypass was it.  I removed & repaired them all, and took S-mtr & AVC voltage
readings across all bands, with fixed sig. gen. input.  I was getting S-9
plus, up to +21db on all bands exc. #3 (see below) & BCB, which was S-7 to
S8-9.  Definitely lower than others, so as Barry points out, it's "supposed
to be" that way.  I can provide all readings if you'd like, but you get the
idea, BCB down abt 6db, like the svc data says.
    I fussed with this rcvr several times over abt 18 mo.s, finally gave up
on getting it to track, sensitivity-wise, on band 3, the one with 40m near
the middle. I did obtain a replacement band 3 coil, no difference.  Tried
chasing down all possible causes, gave up in frustration.  Sold it cheaply,
with the problem properly identified to the buyer.
73,
Al, W8UT
New Bern, NC
BoatAnchors appreciated here
anchor at ec.rr.com
http://www.thecompendium.net/radio/
http://www.hammarlund.info

And remember; "-They don´t make tubes nowadays like they used to..."


----- Original Message -----
From: "Barry Hauser" <barry_hauser at juno.com>
> The "Performance Data for Service Engineers" for the SX-71 shows specs
> for sensitivity on BCB ranging from 5.3 uV at 1.5 Mhz down to 13 uV at
> 0.6 Khz.  That's well apart from the 1.5 uV or less on most all other RF
> ranges.  So, sounds like it's supposed to be that way, or, as they say in
> the hallowed halls of high-techdom -- "Maybe it ain't broke, dude"
>