I just got a TR-4. It has some problems, I have Garey's
disc and have gone over it although there is a lot of stuff
there so I may easily have missed something. The rig came
with an AC-4 with the Heathkit shop mod. I have also tried
with the modified AC-4 I use for my T-4XB to eliminate the
power supply as the cause.
1, As received power output was very low, about 60 Watts on
20 and 40m, did not check it on 80. I replaced the tubes
with some I had, probably used, got the level up to about 80
watts on 80 and 40. I have not yet tried a tune up.
2, Receiving; on 40 meters the RF tune will creat what
sounds like regeneration at some points. There is a definite
peak in the signal and then the ringing. Could this be a bad
cap somewhere, is it common?
Receiving; on ten meters, all three segments, there is
considerable hum and the frequency is off and drifts. I
think three separate crystals are used, maybe all three are
bad but I think is has to be something else.
3, Both sides of the meter bounce badly. One of the notes in
Garey's compendium suggests this is due to age but permanent
magnets don't often behave that way unless shocked or
subjected to a strong demagnetizing field. What is going on
here?
When first fired up one of the receiver sidebands was
obviously way off and was affected by wiggling a tube. I
opened the bottom and probed around a little. I found that
evidently the IF crystal had moved enough to touch something
and pushing a bit cured this problem. There could well be
other artifacts of shipping despite there being no apparent
damage.
All of the above problems, except for the low power,
may respond to the usual voodoo of working screws and poking
at wires. I will know more tomorrow.
Other observations: The receiver seems to be quite hot
and has very good selectivity as one would expect from 8
pole filters. Audio quality is very good. The dial takes
some getting used to, my eye keeps drifting off the band in
use. Calibration is OK, the PTO is reasonably linear. I
intend to use this rig primarily for SSB so the lack of a CW
filter and means to adjust the tone is of little concern.
Brief transmitting tests into a dummy load and
monitoring on the R-388 indicates the transmitted audio
quality is very good. The AGC works well and allows
significant increase in average power without distortion.
A final note on the MS-4 speaker; I got the MS-4 with
the rig. I've tried with and without the AC-4 installed. I
also checked it using an audio oscillator and compared with
an ancient jensen 10" speaker for a Hammarlund HQ-129-X,
which is the best of the speakers I have at the moment.
It is not any "thinner" sounding than the Hammarlund,
which has a pretty good Jensen speaker in it. It has good
voice communication quality, I am not sure replacing the
cone with something else would really make a desirable
difference although a modern high compliance, low
efficiency, speaker would have more low end. Keep in mind
that the rig has very narrow and sharp filters in it so
there really is no low end to be reproduced. The speaker
sounds perhaps just a bit better without the power supply in
the box but it also probably has a tube resonance (tubular
enclosure not vacuum tube), I will have to calculate it.
While one note in Garey's collection states that using a
4 ohm speaker is critical I think this really should make
very little difference considering the lack of constant
impedance of any free-cone speaker and the nature of the
amplifier. In fact, the Hammarlund/Jensen is an 8 ohm
speaker (measured) and is just as loud. Actually, its louder
than some 4 ohm speakers I have both on the Drake rigs and
on the R-388. BTW, while the Collins RX is 4 ohms out also
the Collins speakers are advertised in the old catalogues as
being 8 ohms and the parts list shows them to be 6-8 ohms.
Its a non-issue.
--
Richard Knoppow
Los Angeles
WB6KBL
[email protected]
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