[R-390] New Project (Progress)

[Craig C. Heaton]

-----Original Message-----
From: r-390-bounces at mailman.qth.net
[mailto:r-390-bounces at mailman.qth.net]On Behalf Of Carole White-Connor
Sent: Thursday, February 22, 2007 7:34 PM
Cc: r-390 at mailman.qth.net
Subject: [R-390] New Project (Progress)



Well, we're getting somewhere:

1. The PTO problem was a loose coupler. I loosened a clamp, fit the ridges
and
indentations, tightened it up, and it works. It's 25 khz off but I'll fix
that
later. You folks pointed me in the right direction there. Thank you.

Fix this problem first, mechanical alignment has to be right before any
thing else!

2. I have reception on all bands. However, there is a lot of hiss/static and
sensitivity is not where it should be. This may be a long-standing problem
with
this radio. I see that the IF gain is set at max. If I back it off a bit, I
lose
a lot of sensitivity. Any ideas? Reception is consistent on the bands above
and
below 8 mhz. The noise limiter works well to remove a fair amount of the
hiss/static.

Again, Chapter 6 in the Y2K manual has the adjustment for the IF gain, from
memory about -7 volts at the diode load terminals with 150mV with your
sig-gen 455KC.

3. I tested the tubes and replaced 4-5 that were weak or had shorted
elements. I
noted minor improvement.

4. Reception on the 0-1 mhz band is really lousy. Strong BCB stations come
in
weakly. This is the only band that is this bad. (The 2-3 mhz band may be
bad,
too, but I haven't played with that band too much).

Could be IF alignment or RF alignment, check after mechanical alignment.

5. The crystal oven heats up even though the switch on the back is off. I
disconnected a lead from this switch to disable it, but the oven still
heats. Is
this a problem? Is there an easy way to disable it?

The crystal oven on the RF deck being warm is normal, it is not connected to
the switch on the back of the receiver.

6. On a strong local AM station, the audio is strong and clear. On the
strong SW
stations I receive, the audio is good, too.

I'm just wondering where I should go and what I should do next. Again, my
test
equipment is limited to a VTVM, signal generator and tube tester. So far,
I'm
having fun with this set and am learning a lot. The Y2K manual is a amazing.
I
wish I had something comparable for every set I work on. Any ideas or
suggestions would be gratefully appreciated!!


Joe Connor

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