thanks again, richard. i am printing this whole train out to go down
everyone's checklists. yes, i have an eico sig gen,almost as old as
the set. i check it against an aor 8200 scanner set for the target
freq at each alignment. it is usually really close to right on the
money. have an old tek 465b 200mhz, which is still something of a
mystery, but i can use it in simple ways. i think i can find the
output. tube-tested the mixer/osci tube itself, and again got ok.

have also an eico signal tracer, but have only read a bit about how to
use.

i do plan to check the tuning cap wiring. i did redo the solder
joints, and while i did photo and mark the wires as the old came out, i
could have made a mistake. it should be easy to undo and jumper to
check -- mistake would have to be in center gang area. wires not long
enough to grossly change where they go.
it will take me a while to go thru all this -- thank you all.
ab

Richard Knoppow wrote:
"ablebravo" wrote in message
ups.com...
thx richard. esp on how to test the coils. i will do
that before
checking the IF again. i am suspecting the IF because a
couple of the
adjustments were near the travel limit, which may mean i
am in wrong
place. where it works, it's hot.

i was pretty sure on the tuning gang -- could adjust the
vanes and get
the crackle to change and nearly disappear. i flushed it
good, blew it
out and cleaned and cleaned. after spending hours on it,
i bought the
part. i think something might have been in the bearings.
in the
'crackle spot' the signal died and set could not be
aligned. it
blotted out some of the align freqs. no such prob
w/replacement part.

ab

Do you have a signal generator of some sort? I thought
from your posts that you do. You really do need one to set
up the IF amplifiers. It should be capable of putting out
455 khz preferably with some modulation. The usual
requirement is for 400hz at about 30%. The modulation level
is not critical but most signal generators are not capable
of high modulation level.
Its also helpful to have a crystal calibrator, preferably
one which puts out fairly low frequency markers in addition
to higher frequency ones. 10khz is nice to have. Mine has
100khz, 1.0 mhz, and 10mhz. This can be used directly to
calibrate the receiver and also to calibrate the signal
generator. If you don't have these tools perhaps you can
borrow them.
If the IF transformers are near the limit of their
adjustment, and you know the test frequency is correct, its
probable the resonating capacitors have drifted in value. I
believe this receiver uses permeablility tuned IF coils
(asjustable dust cores).
Again, since the problem seems to be isolated to two
bands and at least one band works OK I think the IF is not
at fault, or at least not the main cause of trouble. I
suggest checking the wiring of the tuning capacitor again to
make sure its OK. You might want to check the other
capacitors in the oscillator and RF stage. I am suspicious
of the oscillator because you say it quits near the low end
of one band. That sound to me like a bad coupling capacitor
there. If you have access to a good RF voltmeter or
reasonably wide band oscilloscope you can check the output
of the oscillator. Even a pick-up loop will show if the
output is varying a lot or if the LO is quitting at the low
end of a band.
Just some things to look for. Remember, this RX is more
than fifty years old so it may have a lot of tired parts (so
do I).


--
---
Richard Knoppow
Los Angeles, CA, USA

"ablebravo" wrote in message
ups.com...
thanks again, richard. i am printing this whole train out
to go down
everyone's checklists. yes, i have an eico sig gen,almost
as old as
the set. i check it against an aor 8200 scanner set for
the target
freq at each alignment. it is usually really close to
right on the
money. have an old tek 465b 200mhz, which is still
something of a
mystery, but i can use it in simple ways. i think i can
find the
output. tube-tested the mixer/osci tube itself, and again
got ok.

have also an eico signal tracer, but have only read a bit
about how to
use.

i do plan to check the tuning cap wiring. i did redo the
solder
joints, and while i did photo and mark the wires as the
old came out, i
could have made a mistake. it should be easy to undo and
jumper to
check -- mistake would have to be in center gang area.
wires not long
enough to grossly change where they go.
it will take me a while to go thru all this -- thank you
all.
ab

Richard Knoppow wrote:
"ablebravo" wrote in message
ups.com...
thx richard. esp on how to test the coils. i will do

Long thread snipped...

If you need a handbook for the Tek 465-B there is one on
the BAMA site at:
http://bama.sbc.edu/tektroni.htm
And for Eico instruments at:
http://bama.sbc.edu/eico.htm

This is a very good site to bookmark.

The signal tracer is a wide band amplifier with a
detector on it. You can probe around in the circuit to find
out what is there. That and the scope are powerful tools for
analysing exactly this sort of problem. You can use the
scope with either a high impedance probe or a simple pick-up
loop to look at the oscillator output. The look will cause
the least disturbance to the circuit you are measuring.


--
---
Richard Knoppow
Los Angeles, CA, USA

i think you have nailed at least part of it -- rf stage. i have
emailed you offline details. had a completely dead rf amp tube, ahead
of the IF stage. this apparently forced a pretty severe tuning
compensation that affected the bands (?). all tubes tested before
starting work, but this one croaked sometime during repairs. found
intermittent black speaker lead and fixed. was cutting out also. so
there's some of it. already better w/if and bfo align redone. will
see what gives after i finish all rf again... hopefully it will come
back into line on all bands. yes i go first to bama for all.
bookmarked on about 4 computers i have.
ab


Richard Knoppow wrote:
"ablebravo" wrote in message
ups.com...
thx richard. esp on how to test the coils. i will do

Long thread snipped...

If you need a handbook for the Tek 465-B there is one on
the BAMA site at:
http://bama.sbc.edu/tektroni.htm
And for Eico instruments at:
http://bama.sbc.edu/eico.htm

This is a very good site to bookmark.

The signal tracer is a wide band amplifier with a
detector on it. You can probe around in the circuit to find
out what is there. That and the scope are powerful tools for
analysing exactly this sort of problem. You can use the
scope with either a high impedance probe or a simple pick-up
loop to look at the oscillator output. The look will cause
the least disturbance to the circuit you are measuring.


--
---
Richard Knoppow
Los Angeles, CA, USA

all tubes tested before starting work, but this one
croaked sometime during repairs.

I just picked up on this thread and read it with interest. Sounds like
you're on the right track. That's a nice receiver when working correctly.

One thing I'm beginning to appreciate about fixing old radios & TVs is that
some components which test "good" or seem acceptable at first, may decide to
give out after a few more hours of operation. The tube (or whatever) may
simply have reached the end of its service life, or perhaps it croaked after
running at full power for the first time in decades.

Before I declare victory on any project, I run it on the workbench for some
hours. Much better to find and correct those latent issues now, rather than
later.

Have fun,

Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html

"Phil Nelson" wrote in message
...
all tubes tested before starting work, but this one
croaked sometime during repairs.

I just picked up on this thread and read it with interest.
Sounds like you're on the right track. That's a nice
receiver when working correctly.

One thing I'm beginning to appreciate about fixing old
radios & TVs is that some components which test "good" or
seem acceptable at first, may decide to give out after a
few more hours of operation. The tube (or whatever) may
simply have reached the end of its service life, or
perhaps it croaked after running at full power for the
first time in decades.

Before I declare victory on any project, I run it on the
workbench for some hours. Much better to find and correct
those latent issues now, rather than later.

Have fun,

Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html

Its possible for tubes to have bad seals or very slight
cracks that allow some air to get in. The "getter", which is
the silver stuff on the inside, can absorb only so much air
after which the tube will simply not operate. Sometimes the
symptom is a blue glow inside the tube, something like the
glow in a voltage regulator tube. This should not be
confused with the slight dark blue glow somtimes seen in
beam power tubes with very high voltage on the plates. This
is not due to air and is normal.
It is also pretty common for resistors and, especially
capacitors, to die after being unused for a long time. There
are many causes, moisture absorption and others. Even
transformers may die shortly after being fired up after
being unused for a long time.
A useful tool when working on old equipment is a metered
variable transformer. Ideally, it should have both a voltage
and current meter on the output. The current meter is
especially important since it will show excessive current
before damage is done. My suggestion is to remove rectifier
tubes from the equipment and bring it up slowly on the
transformer. If there is any sign of excessive current turn
it off immediately. If it looks OK this way try again with
the rectifiers, again bringing the voltage up slowly. Of
course, the filter capacitors should be checked first for
shorts.
Most electronic equpment likes to run. Leaving it off and
in storage for long periods is not good for it. I suspect
nearly everyone who follows this group already knows all
this stuff.


--
---
Richard Knoppow
Los Angeles, CA, USA

hi phil -- i have read, reread, and printed a good bit of your site. i
think i actually got the link to this forum there as well. i couldn't
get by w/help of yourself and the others here who are good enough to
invest the time....
ab

Phil Nelson wrote:
all tubes tested before starting work, but this one
croaked sometime during repairs.

I just picked up on this thread and read it with interest. Sounds like
you're on the right track. That's a nice receiver when working correctly.

One thing I'm beginning to appreciate about fixing old radios & TVs is that
some components which test "good" or seem acceptable at first, may decide to
give out after a few more hours of operation. The tube (or whatever) may
simply have reached the end of its service life, or perhaps it croaked after
running at full power for the first time in decades.

Before I declare victory on any project, I run it on the workbench for some
hours. Much better to find and correct those latent issues now, rather than
later.

Have fun,

Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html