[Hallicrafters] SX-117 VS SX-115 Part 2

[Duane Fischer, W8DBF]

Hi again,
 Here's the 2nd installment of the SX-117 saga #1 was my
intial 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
accorking 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
hamband 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 like
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
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