[Hallicrafters] SX-117, SX-101A, SX-115 impressions/comparison - long

[Al Parker]

Hi folks,
    I originally posted this to the Hallicrafters list, in 2 parts, in
Apr. 2005.  The subject comes up abt 1/yr, so here it is again.
73,
Al, W8UT
New Bern, NC
BoatAnchors appreciated here
http://www.thecompendium.net/radio/
http://www.hammarlund.info

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Date: Thu, 06 Apr 2000 09:55:24 -0400
From: Al Parker <anchor at coastalnet.com>
Subject: SX-117 impressions/comparison (part 1)

Hi folks,
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

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Date: Thu, 06 Apr 2000 10:00:38 -0400
From: Al Parker <anchor at coastalnet.com>
Subject: SX-117 impressions/comparison (part 2)

Hi again,
   Here's the 2nd installment of the SX-117 saga.  #1 was my initial
impressions upon recpt, this one covers alignment & "final" impressions:
"50" kc 3rd IF peaked (as found) at about 48kc.  With coil slugs in all
the way, it could be moved to 50.75, the proper spot.  I thought coils in
like that wasn't very good, indicated another problem.  But, being lazy, I
didn't try to determine the problem.  I thought, 50.75 is 750cy above 50,
the nominal IF, which is actually what the 2nd IF expects to feed (see
later).  So, 750cy under 50 kc should also be acceptable.  I set it there,
and it was fine.
  2nd IF, 1650kc.  It had peak thruput at 1651.3 (as found).  The manual
says to find the peak at the 5kc selectivity position.  I checked the
actual upper & lower SB oscillator xtal freq.s, 1700.003 and 1600.028.
Close.  Half way between is 1650.015.  After peaking to the 5kc
selectivity position, the following peak thruputs were measured--.5kc
select - 1650.28;
   2.5kc sel - 1650.73;  5kc sel - 1650.04   Looked good to me.
Sensitivity-as found, and represented by the very informative seller, it
was low on 15 & 10 meters.  It was good on the low bands.  I don't think I
did an actual 50uv=S-9 check, but as a rough guess, I'd say if 50uv was
S-9 on 20m, it may have been S-5 on 10m.  As I mentioned in pt. 1, the
preselector alignment is the key to sensitivity performance in this rcvr.
It is the primary adjustable item in the RF stage, from 3 to 30mc, and is
not switched, except for small shunt coils on 15 & 10m.  The manual calls
for "supplemental" xtals of 9.5 & 18mc for proper adjustments at 3mc,
11.5mc, + 28, which uses the installed xtal.  I initially tried "winging
it", without much thought to best optimization with what I had (no extra
xtals).  It didn't come out any better than it was.  I tried the trial and
error method, to reach a compromise, hoping for better gain at 10m, with
possible less on low bands.  No luck.  Finally, after a little
consideration, I figured I don't need 3mc, so I could use 3.5, the lower
end of 80, to 28, with a mid-point ck at 10 or 14, vs the 11.5 called for.
This worked out fine, now, 50uv give S-9 on all bands except 10m, which is
about S-8, and 80, which is about 5-10db over 9.  I'm happy with that.
The xtal osc. output should be checked and adjusted according to the
manual.  If output is way down on any band, overall gain is reduced on
that band.  I had one xtal a bit low, not bad, but it seemed to produce
"birdies", or maybe images, if the preselector wasn't peaked closely to
proper.  you figure.  The seller had an extra xtal which he sent later,
n/c.  (he's been a great guy to buy from)
   Impressions after alignment-unwanted sideband rejection is better, but
still not as good as the SX-115, or even the 101A.  Overall sensitivity is
fine, maybe not as good as the 115, but about the same as the 101A.
Selectivity is OK, maybe not quite as good as the SX-101A.  Notch filter
works well, like the 101 & 115.  Some guys complain about poor notch
filter perfomance on these rcvrs, I think 50kc IF peaking, & notch filter
adjustment should resolve that.
    Ease of use-I don't really like the small dial frequency window, and
the "approx. 1-kc marks", unlabeled, on the tuning dial skirt.  There's 15
marks/rev, but 10-kc major, & 5-kc minor marks on the dial in the window,
which is 0-500kc, not showing the band (but this is a "general coverage"
rcvr, so it's as it should be).  This is just personal preference, not
criticism.  The preselector operation is much like the Drakes', which is
fine.  It's easier to know more closely what freq. you're on than the
SX-101, but not nearly as nice as the 115, which has 1-kc markings,
labeled, 25/rev., on the tuning knob skirt, much like Drakes.
   Overall-The SX-117 is a neat rcvr, you can put xtals in for 'most any
500kc segment anywhere, similar to the Drakes.  They've made "adjustments"
to make that possible, which do detract somewhat from what most of us
would like for ham-band performance.  The SX-115 and SX-101's are ham and
only, and  are better performers there than the SX-117.  I guess I'd agree
with Mike, the 101A is a better rcvr, on ham bands.  We both have & like
the SX-101A.  I have an SX-115, it's the best of the 3.
   I hope this will answer some questions about these rcvrs, I'm sure
others have their own opinions, I'd be happy to hear any thoughts, input,
tips, etc.  I mentioned several weeks ago, on the Hallicrafters email
reflector, and the HCA nets that I had the 117 & hoped to make some useful
comparisons.  A lot of folks expressed interest, as 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.  You may make your own conclusions.

73,  Al, W8UT,  New Bern, NC
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