[NJARC] Hallicrafters SX-16

[Scott Roberts]

Just thought I'd update those paying attention to my latest
efforts...

I found the problem with the Frequency Counter(Heathkit) and the
Signal Generator(Also Heathkit)- Operator error. I found it takes
100mw output on the generator to get the counter adequately fed.
Once that came to pass, everything started working with them. I
then proceeded to have problems with the signal tracer(guess
who). That I haven't resolved yet.

Anyway, once I had the main test equipment on line, I started
futzing with the SX-16. First I retested the audio circuit, using
the detector grid finger tap test. Worked well- got a good hum,
although not quite as loud as I'd have liked, so I moved the
speaker from the headphone jack to the 300ohm output. Fixed That.

So I proceeded to look for the problem getting signal into the
set. It had been working before I recapped it... I took out my
few repairs(other than caps) and put back in the original
component, one at a time. Nothing. The 10mmf cap I'd replaced
even fell apart in my hand! Guess it DID need replacement after
all... So, after that, I went to playbook B.

With the chassis upside down, and operating, I fed an 800khz
signal into the antenna, with the dial set around 800 khz... And
I started tapping components with a fibreglass rod. I tapped
Capacitor C-34, I got a result- Noise! I kept tapping along the
leads in each direction, and found it used the mixer tube 6L7 #8
as a cross tie to ground, and at that point Resistor R-9(285ohm)
was also connected. I tapped into the resistor, and got differing
results... I looked the resistor over, and noticed it ooked a
little beat up. Not having a 1/5w, 285ohm resistor, I joined a
270 ohm and a 10 ohm in series, and replaced R-9. Then I got Good
Noise, and was able to tune in the signal generator quite well.

I hooked up the antenna, and started receiving immediately.
1210am is local and very strong, so I tuned it in, and did a fast
IF tune by ear, but it didn't take much. AM seems to be dialed in
pretty well. SO I started spinning through the dial, and was
picking up stuff on most of them. On the bands which had nothing
coming through, I ran a signal generator tone, and checked them
at least for reception. Tone came in fine.

Back to AM, I started trying to find something interesting among
the multitudes of stations coming through loud and clear. At
1120AM I got a nice signal with some really cool bluegrass, so I
stopped there- only to find that signal was nesting in the middle
of another 1120AM signal! I was receiving both 1120 KMOX, St
Louis, Mo.(860 miles), and 1120 WSME, Jacksonville NC.(around 500
miles) (Both also have online listening, so I was able to confirm
by what was playing.) Shifting a little, I got a strong signal
from 1110 WBT, Charlotte, NC.

This was all on my shorter test antenna- after I do a full
alignment, I will hook it up in the living room, to the longer
"Alzwhire" antenna, and see what I get. (I may be replacing the
"Azwhire" with a Slinky soon- just have to get around to getting
into the attic again...)

Anyway, I thought it wasn't too bad for a first try after major
work! Should be on top of my game for the next DX contest... ;)

Scott


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