[Hallicrafters] SX-117 Tech Tips

[Duane Fischer, W8DBF]

Here are some tech tips that I hope benefit those on the Hallicrafters list.

They will soon be available for download from the Hallicrafters web site! 
Keep squinting -

 Several weeks ago I got an SX-117.  I got it mostly out of
interest, since
I've had several SX-101(&A)'s, and had just finished refurb
of an SX-115 to
replace the latest 101A.  I wondered what the differences
were in
construction & performance.  I had mentioned its' arrival on
the list, and
there was interest in my thoughts, so here are some.  The SX-
115, and the
SX-117 are not too common, are very similar in design, and
some think the
117 should be a "poor man's" 115.  I'll put my first
impressions in this
"part 1" and continue with the alignment & final impressions
in "part 2".
 I sent the following, slightly edited, to the seller, who
was very
interested in my impressions & satisfaction:
 I listened to it a while last nite, and will list my
impressions.  Realize
that it was late and brain cramps were setting in ;-)
 Sounded good on 20m, & like you said, sensitivity seems down
on 15 & 10,
but you do hear noise peak up with the preselector, so that
shows that the
RF stage is doing something there.  The xtal calib. is very
weak on 15 &
10, and I think I heard some sort of image near it there -
strange one,
about 15kc away, I think.
 The RF ckt is much different than the SX-115.  The 115 has
separate
switched coils for each 500kc band, the 117 has a broadband
sort of amp,
peaked in the input & output by preselector variable cap.
only on 15 & 10
is anything switched, a shunt inductance, in both the input &
output.
Maybe there's some hope there, as the shunt goes in series
with an
adjustable inductance.  The broadband preselector arrgt
allows bcst bands,
WARC, etc, to be utilized, can't do that on the 115.
 The unwanted sideband rejection is terrible.  I can listen
to USB signal
on either USB or LSB position, and same on CW, very little
"single signal"
effect.  Probably the 1650 kc alignment will fix this.  The
115 2nd IF is
1000kc +-, the 101 is 1650, I think, like the 117.  Should
get similar
results, signal wise, as the 101, at least.
 The BFO freq. is off, minor adjustment reqd after 3rd IF
alignment.  The
notch works well, so 3rd IF must be on freq.  I notice the
notch doesn't
affect the S-meter.  The AGC arrgt is different than the 115,
which has a
double loop & is very good.
 Still some hum when AF is turned way up, not to worry.
(seller had
replaced the pwr supply filter cap.)
 Selectivity is good, similar ckt to the 115, but not as many
positions.
So, that's a quick first look.  No show stoppers.  I won't
get to alignment
for a few days, want to do an SX-101A first, the one that the
115 replaced.
 I never did anything to it when I got it, other than a minor
fix, just
plugged it in & used it for several months.  I washed it
yesterday, had
touched up the cabinet a week or 2 ago.  Think I'll take it
to a 'fest a wk
fm Sun.  (it sold b4 I got there)
 I realize I haven't said much positive, but that doesn't
mean there isn't.
 I was pleasantly surprized when I picked it up - much
lighter that what
I've been hefting lately (SX-101, HT-37, SX-115).  And well
enuf
constructed so there should be no flexing.  The panel & knobs
are very nice
(the funny mark on the bezel I think can be figured out &
minimized).  The
cabinet had been repainted, maybe slightly lighter than the
bottom cover
shows.  It's clean inside.  I notice that the antenna
connector, which I
think you mentioned, is original, with the added adapter for
BNC.  It's
strange that they put in the holes for a regular coax jack,
but the manual
pic  shows the holes, no jack.
 I'll keep you posted on progress & any other observations.
I may have
missed a few above.  I guess I did ck it out pretty well in a
short time.
Didn't even switch to 80m.
 I got into it b4 going to the SX-101A, and will continue in
part 2.  I can
just say now, quickly, that it seems to me that the key to
"enjoyment" of
this receiver is the proper alignment of the preselector, to
flatten out
the sensitivity over the bands.  It is a broad-band thing, so
hard to get
the ends "up".
73,

Al, W8UT
New Bern, NC
BoatAnchors appreciated here
anchor at coastalnet.com

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


Duane Fischer, W8DBF - WPE8CXO
E-Mail: dfischer at usol.com
Hallicrafters web site: www.w9wze.net
HHRP web site: hhrp.w9wze.net