[Drake] TR-4 question

[David Harmon]

Hi Jerry....try this....

My TR-4CW/rit neutralizing cap is 45 degrees open from full mesh. You
can compare yours.

In this case, I would neutralize on 40 mtrs first, then try 20, etc and
see what happens. 
Follow the book procedure except start on 40mtrs.

If you have another set of PA tubes you could try exchanging them.

You can remove the PA screen and plate voltages to kill the PA....leave
the PA tubes installed and then check out the driver stages for the
bands in question.
Listen on a rx for good SSB with the PA disabled.

Check PA grid bandswitch contacts....they may be missing or not making
contact for some reason....I imagine if the PA grid (driver plate) ckt
was open the PA might take off.

PA plate bandswitch contacts not making contact or PA coils broken
somewhere.

Look for poor/cold solder joints on the driver stages. There are a bunch
of leads on the bottom of the chassis soldered to the pins of the driver
transformers.
My rig had an intermittent drive problem on 40 mtrs and a poor solder
job is what caused it.


Regards

Dave Harmon
NSRCA 586
K6XYZ[at]comcast[dot]net
Torrance, Ca.

-----Original Message-----
From: drake-bounces at mailman.qth.net
[mailto:drake-bounces at mailman.qth.net] On Behalf Of Jerry Kincade
Sent: Monday, June 07, 2004 3:03 PM
To: Drake at mailman.qth.net
Subject: [Drake] TR-4 question

I have a new (to me) nice looking TR-4 on the bench, checking it out.
Haven't messed with Drakes for years, last one was an old beat up TR-3
years
ago, so I am looking for some advice. This one works gangbusters on 80
and
40, and receives fair on 20, 15, and 10. However, the finals won't load
on
20 and above, with all three bands (20, 15,10) giving the same
indication,
namely a nearly uncontrollable peak in plate current where there should
be a
dip. Things seem normal as I key it and increase Transmit Gain slowly up
from idle current to get enough Ip to be able to see a dip (with PLATE
and
LOAD controls at zero), but then Ip takes off out of control as soon as
I
tune for a dip, with the Ip peaking at about the point on the plate
tuning
where I would expect to see a dip instead. What really surprised me was
the
Bird meter shows significant power out (80-100 watts) in consonance with
the
unwanted Ip peak. This is no nickle-dime problem, Ip will jump to 600 mA
plus if I let it. Needless to say, I don't leave it long in that
condition.
:-)

 Also, there is no definite noise peak on receive on the three problem
bands
when using the RF TUNE control, although receive seems at least fair
(sensitivity seems a bit weak to me on 20 and above). 80 and 40 have
clear
and definite noise peaks on receive using RF TUNE, with good
sensitivity. My
first thought was improper neutralization, but per the book to
neutralize it
you first have to tune up normally on 10, and that is not possible in
this
instance. Besides, neutralization is intended to make max power and
mininum
plate current occur at the same point, and that doesn't seem to be the
problem here. I'm thinking I have more wrong here than a simple
neutralization problem, and am wondering if maybe someone in the past
has
attempted to "align" the transmit chain on 20-15-10, hosing things up.

I also may have a serious parasitic problem, but I fail to see why that
would occur in exactly the same way on three bands... ??

Next I will likely try the basic book alignment to see if anything has
been
drastically mistweaked, but first wondered if anybody has any ideas.
Finals
are new, and work great on 80 and 40, with smooth and clean peaks/dips
and
it easily puts out 140-150 watts at 375-400 mA Ip on those bands, with
clean
audio out on both USB and LSB.

Any ideas before I wander further into the woods with this thing? This
TR-4
is not a junker, it's extremely clean inside and out, and appears to
have
been well cared for. No mods are evident, and it does not appear to have
ever been subjected to a soldering iron.

Any sage advice from experienced Duck experts would be appreciated.

73, Jerry W5KP



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