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Plotus November 26th 10 02:48 PM

TUBE Cooling? Yes or No?
 
With the Hammarlund HQ120 that I recently purchased, If been having a great time DXing on all the bands and learning the in's and out's of this particular Vintage radio operation. However, yesterday I lost my OD3 tube. While working, I noticed that it put off a what appeared to be... ultraviolet or bluish colored light, and about mid-day the radio quit working. Wondering what might have went out, I let the radio return to room temp and later turned it back on with the top lid opened a couple inches to view the bulbs in operation. From what I could see, they all lit except the OD3 tube which I initally noticed because of the color, so I asume that is the cause of inoperability. I got online and bought a tube kit which included a complete HQ120 tube-set. I have no idea of course as to the lifespan of the old 'original' ....OD3 tube and if it's 'is' original or has been replaced sometime in the life of this radio.

Back to the title of this post.... should one operate the HQ with the lid opened for cooling or add additional fan cooling from an outside source? Also I was operating this in an enclosed cabinet with sides, top and back, with about 8-10" of open space all around the radio? The inside temp of the room was probably 60 or so degrees, so it was typical cool fall weather. SHOULD I also cool and have the hood open? and should it be in a more open environment? Thanks......... Plotus AKA Richard...

Edward Knobloch November 26th 10 05:31 PM

HQ-120 was TUBE Cooling? Yes or No?
 
On 11/26/2010 9:48 AM, Plotus wrote:
snip However, yesterday I lost my
OD3 tube. While working, I noticed that it put off a what appeared to
be... ultraviolet or bluish colored light, and about mid-day the radio
quit working. Wondering what might have went out, I let the radio return
to room temp and later turned it back on with the top lid opened a
couple inches to view the bulbs in operation. From what I could see,
they all lit except the OD3 tube which I initally noticed because of the
color, so I asume that is the cause of inoperability. snip


Hi,
An 0D3 tube normally glows blue or pink when operating.
It is a gas-filled voltage regulator,
and operates like a 150V Zener diode.
The fact that the 0D3 is now dark and your radio has stopped working
indicates that you have lost the dc supply in your HQ-120.
I'd look carefully at the electrolytics in your power supply,
one may have developed a short.

73,
Ed Knobloch


KD7HB November 26th 10 08:20 PM

HQ-120 was TUBE Cooling? Yes or No?
 
On Nov 26, 9:31*am, Edward Knobloch wrote:
On 11/26/2010 9:48 AM, Plotus wrote:

snip *However, yesterday I lost my
OD3 tube. While working, I noticed that it put off a what appeared to
be... ultraviolet or bluish colored light, and about mid-day the radio
quit working. Wondering what might have went out, I let the radio return
to room temp and later turned it back on with the top lid opened a
couple inches to view the bulbs in operation. From what I could see,
they all lit except the OD3 tube which I initally noticed because of the
color, so I asume that is the cause of inoperability. snip


Hi,
An 0D3 tube normally glows blue or pink when operating.
It is a gas-filled voltage regulator,
and operates like a 150V Zener diode.
The fact that the 0D3 is now dark and your radio has stopped working
indicates that you have lost the dc supply in your HQ-120.
I'd look carefully at the electrolytics in your power supply,
one may have developed a short.

73,
Ed Knobloch


My guess would be the the dropping resistor in series with the 0D3.
The 0D3 probably supplies the oscillator and possible the bfo tubes.
So, they won't work and you won't receive anything. However, you
should be able to still get some sound from the audio stages.

The other possibility is the rectifier died and then you will not have
any audio output and the 0D3 will not light. Look for the heater in
the rectifier, 5Y3?, should be glowing.

If you detect a bad smell, then it is more serious!

Paul, KD7HB

Plotus November 27th 10 12:00 PM

Quote:

Originally Posted by KD7HB (Post 724314)
On Nov 26, 9:31*am, Edward Knobloch wrote:
On 11/26/2010 9:48 AM, Plotus wrote:

snip *However, yesterday I lost my
OD3 tube. While working, I noticed that it put off a what appeared to
be... ultraviolet or bluish colored light, and about mid-day the radio
quit working. Wondering what might have went out, I let the radio return
to room temp and later turned it back on with the top lid opened a
couple inches to view the bulbs in operation. From what I could see,
they all lit except the OD3 tube which I initally noticed because of the
color, so I asume that is the cause of inoperability. snip


Hi,
An 0D3 tube normally glows blue or pink when operating.
It is a gas-filled voltage regulator,
and operates like a 150V Zener diode.
The fact that the 0D3 is now dark and your radio has stopped working
indicates that you have lost the dc supply in your HQ-120.
I'd look carefully at the electrolytics in your power supply,
one may have developed a short.

73,
Ed Knobloch


My guess would be the the dropping resistor in series with the 0D3.
The 0D3 probably supplies the oscillator and possible the bfo tubes.
So, they won't work and you won't receive anything. However, you
should be able to still get some sound from the audio stages.

The other possibility is the rectifier died and then you will not have
any audio output and the 0D3 will not light. Look for the heater in
the rectifier, 5Y3?, should be glowing.

If you detect a bad smell, then it is more serious!

Paul, KD7HB

I did have a distinct acrid odd smell, no smoke was discernable and the radio still powers up but will not tune in any band. The on/off/audio gain switch turns on the radio of course and the ever present low decible hum is present. Thanks for the tips and info guys.

I have found a semi-local (75 miles away) restoration/repair shop David De Betta in Pineville NC. I'll be contacting him this morning hopefully to schedule a repair. At this juncture of my novice knowledge, I believe it would be prudent................lol 'GW bush' lol, again thanks.

Scott Dorsey November 27th 10 03:43 PM

TUBE Cooling? Yes or No?
 
Plotus wrote:

With the Hammarlund HQ120 that I recently purchased, If been having a
great time DXing on all the bands and learning the in's and out's of
this particular Vintage radio operation. However, yesterday I lost my
OD3 tube. While working, I noticed that it put off a what appeared to
be... ultraviolet or bluish colored light, and about mid-day the radio
quit working.


The OD3 is a cold-cathode regulator tube. It's supposed to be glowing
with a blue light, that is how you know it is working. You can tell it
is a cold-cathode tube since the first number is a zero, indicating it
has no filament.

Wondering what might have went out, I let the radio return
to room temp and later turned it back on with the top lid opened a
couple inches to view the bulbs in operation. From what I could see,
they all lit except the OD3 tube which I initally noticed because of the
color, so I asume that is the cause of inoperability.


No, it's a symptom that you have no high voltage going into the OD3,
either because it's not coming out of the transformer or because there
is a rectifier or droppin resistor gone bad.

I got online and
bought a tube kit which included a complete HQ120 tube-set. I have no
idea of course as to the lifespan of the old 'original' ....OD3 tube and
if it's 'is' original or has been replaced sometime in the life of this
radio.


It's fine, there's probably nothing wrong with and there's probably nothing
wrong with any of the other tubes either. Heat the thing up, pull the
bottom of the case, and get out the meter. Work back from the OD3 plate
pin to the plug and see where the voltage drops.

Back to the title of this post.... should one operate the HQ with the
lid opened for cooling or add additional fan cooling from an outside
source? Also I was operating this in an enclosed cabinet with sides, top
and back, with about 8-10" of open space all around the radio? The
inside temp of the room was probably 60 or so degrees, so it was typical
cool fall weather. SHOULD I also cool and have the hood open? and should
it be in a more open environment? Thanks.........


It won't hurt to keep it cooler and it might last longer, but if you run
it with the lid open, the RF performance will be degraded since you will
have defeated much of the shielding.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Bill M[_5_] November 27th 10 05:45 PM

TUBE Cooling? Yes or No?
 
Scott Dorsey wrote:


No, it's a symptom that you have no high voltage going into the OD3,
either because it's not coming out of the transformer or because there
is a rectifier or droppin resistor gone bad.


Another possibility would be something on the load side is pulling down
the B+. Short/partial short, etc.

-B.

Plotus November 29th 10 01:04 PM

Quote:

Originally Posted by Bill M[_5_] (Post 724398)
Scott Dorsey wrote:


No, it's a symptom that you have no high voltage going into the OD3,
either because it's not coming out of the transformer or because there
is a rectifier or droppin resistor gone bad.


Another possibility would be something on the load side is pulling down
the B+. Short/partial short, etc.

-B.

The info on sheilding is good to know, I'll start with a replacement OD3, (I have two coming from an ebay supplier) and go from there since I have no test equiptment. If that fails, I'll look into the power supply issue. And probably contact the fella I spoke of above who works on tube radios.

Scott Dorsey November 29th 10 05:57 PM

TUBE Cooling? Yes or No?
 
Plotus wrote:
-B. The info on sheilding is good to know, I'll start with a replacement

OD3, (I have two coming from an ebay supplier) and go from there since I
have no test equiptment. If that fails, I'll look into the power supply
issue. And probably contact the fella I spoke of above who works on tube
radios.


There's nothing wrong with the OD3. Go buy a good multimeter..
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

OldbieOne November 30th 10 10:40 PM

TUBE Cooling? Yes or No?
 
On Fri, 26 Nov 2010 14:48:16 +0000, Plotus did
make me awaken from my chaotic existentialism when they didst announce:

snipped

My bet is you've got a shorted capacitor or another problem in the DC circuit.
After several mystery ailments, I re-capped my HQ-120X and all was well after a
re-alignment, never a problem since.

73


--
OldbieOne -
The guy who tells it like it is!

Plotus December 2nd 10 03:00 PM

Quote:

Originally Posted by OldbieOne (Post 724645)
On Fri, 26 Nov 2010 14:48:16 +0000, Plotus did
make me awaken from my chaotic existentialism when they didst announce:
Sorry guys, I'm still figuring out where to put these replies in these posts. Thanks OB1 and the rest of you guys. A week ago I'd not have knew much or what you said ,....would have been VooDoo Babbel to me.... fortunatly for alot of your previous posts on like topics.... I'v learned much. I got on ebay and bought and recieved an instruction manual, and fortunatly I'm grasping the mechanics and construction of radio building and concepts. I believe armed with these posts of possabilities and an ohm meter and schematic, I'll find the source. I'm also starting to believe that the bottom plate/cover may be touching, and did short something. I purchased rubber sheeting to put on top of the pan. Now if some of my other stuff will arive like tubes... thanks all ...Rich....
snipped

My bet is you've got a shorted capacitor or another problem in the DC circuit.
After several mystery ailments, I re-capped my HQ-120X and all was well after a
re-alignment, never a problem since.

73


--
OldbieOne -
The guy who tells it like it is!

I don't know where to put this reply

Richard Knoppow December 3rd 10 06:13 AM

TUBE Cooling? Yes or No?
 

"Scott Dorsey" wrote in message
...
Plotus wrote:
-B. The info on sheilding is good to know, I'll start
with a replacement

OD3, (I have two coming from an ebay supplier) and go from
there since I
have no test equiptment. If that fails, I'll look into the
power supply
issue. And probably contact the fella I spoke of above who
works on tube
radios.


There's nothing wrong with the OD3. Go buy a good
multimeter..
--scott


Same here, your regulator tube is fine, its not lighting
because the high voltage isn't there. You need a decent
voltmeter. You can get a cheap one that will be good enough
to track down this problem as Radio Shack for a few dollars.
If you have a shorted filter capacitor running the set as
with it is gambling with the power transformer. Without some
measuring tools you are stuck. The handbook for the receiver
is available at the BAMA reflector, do a Google search for
BAMA. The handbook has a voltage and resistance chart in it
which will help isolate the problem.
The HQ-120-X was a very good receiver in its day and
still holds up very well, it is well worth the effort to
repair. Beside which its sexy looking.
I have just been working on its successor the HQ-129-X,
which is very similar and am quite pleased with it.
If you don't know anything about electronic trouble
shooting see if you can get some help from someone local.
Power supply problems are fundamental and, in something as
simple as this receiver, are not hard to find.

--
Richard Knoppow
Los Angeles
WB6KBL




Kenneth Scharf December 5th 10 09:56 PM

TUBE Cooling? Yes or No?
 
On 11/26/2010 09:48 AM, Plotus wrote:
With the Hammarlund HQ120 that I recently purchased, If been having a
great time DXing on all the bands and learning the in's and out's of
this particular Vintage radio operation. However, yesterday I lost my
OD3 tube. While working, I noticed that it put off a what appeared to
be... ultraviolet or bluish colored light, and about mid-day the radio
quit working. Wondering what might have went out, I let the radio return
to room temp and later turned it back on with the top lid opened a
couple inches to view the bulbs in operation. From what I could see,
they all lit except the OD3 tube which I initally noticed because of the
color, so I asume that is the cause of inoperability. I got online and
bought a tube kit which included a complete HQ120 tube-set. I have no
idea of course as to the lifespan of the old 'original' ....OD3 tube and
if it's 'is' original or has been replaced sometime in the life of this
radio.

Back to the title of this post.... should one operate the HQ with the
lid opened for cooling or add additional fan cooling from an outside
source? Also I was operating this in an enclosed cabinet with sides, top
and back, with about 8-10" of open space all around the radio? The
inside temp of the room was probably 60 or so degrees, so it was typical
cool fall weather. SHOULD I also cool and have the hood open? and should
it be in a more open environment? Thanks.........
Plotus AKA Richard...




From the descriptions I've heard your problem is that the power
resistor in series with the OD3 has opened up. The OD3 is used to
regulate the voltage to the oscillator section(s) of the receiver, and
with that resistor open the OD3 gets no power and won't light, the
oscillator in the receiver gets no power and won't work. You will still
get a hum out of the receiver as the AF section is still alive, in fact
if you touch the center terminal of the volume control with a finger
(through a .01uf cap so you avoid touching B+) you should get a LOUD
hum. With the LO and BFO sections dead, a superhet will receive NOTHING
(well if you inject a modulated 455khz signal to the antenna you should
hear THAT).

Look under the chassis for a rather black resistor connecting to the 0D3
socket. Usually resistors don't go bad unless there is something else
wrong, but on an old set like this all bets are off.

Richard Knoppow December 9th 10 01:51 AM

TUBE Cooling? Yes or No?
 

"Kenneth Scharf" wrote in message
...
On 11/26/2010 09:48 AM, Plotus wrote:
With the Hammarlund HQ120 that I recently purchased, If
been having a
great time DXing on all the bands and learning the in's
and out's of
this particular Vintage radio operation. However,
yesterday I lost my
OD3 tube. While working, I noticed that it put off a what
appeared to
be... ultraviolet or bluish colored light, and about
mid-day the radio
quit working. Wondering what might have went out, I let
the radio return
to room temp and later turned it back on with the top lid
opened a
couple inches to view the bulbs in operation. From what I
could see,
they all lit except the OD3 tube which I initally noticed
because of the
color, so I asume that is the cause of inoperability. I
got online and
bought a tube kit which included a complete HQ120
tube-set. I have no
idea of course as to the lifespan of the old 'original'
....OD3 tube and
if it's 'is' original or has been replaced sometime in
the life of this
radio.

Back to the title of this post.... should one operate the
HQ with the
lid opened for cooling or add additional fan cooling from
an outside
source? Also I was operating this in an enclosed cabinet
with sides, top
and back, with about 8-10" of open space all around the
radio? The
inside temp of the room was probably 60 or so degrees, so
it was typical
cool fall weather. SHOULD I also cool and have the hood
open? and should
it be in a more open environment?
Thanks.........
Plotus AKA Richard...




From the descriptions I've heard your problem is that the
power resistor in series with the OD3 has opened up. The
OD3 is used to regulate the voltage to the oscillator
section(s) of the receiver, and with that resistor open
the OD3 gets no power and won't light, the oscillator in
the receiver gets no power and won't work. You will still
get a hum out of the receiver as the AF section is still
alive, in fact if you touch the center terminal of the
volume control with a finger (through a .01uf cap so you
avoid touching B+) you should get a LOUD hum. With the LO
and BFO sections dead, a superhet will receive NOTHING
(well if you inject a modulated 455khz signal to the
antenna you should hear THAT).

Look under the chassis for a rather black resistor
connecting to the 0D3 socket. Usually resistors don't go
bad unless there is something else wrong, but on an old
set like this all bets are off.


The resistor is a 3K, 10W, wire wound. Wire wound
resistors often go open because the joint between one end of
the winding and the terminal on the resistor has opened up
due to corrosion of the weld. Sometimes they can be fixed by
soldering at the joint. Otherwise, this is a pretty standard
value resistor and should not be difficult to replace. If
its just opened up it may look just fine. If it burned up
you would probably smell it. Also check the solder joints to
at the ends of the reisistor and at the terminals of the
regulator tube. These can run hot and fail after a long
period of time.
You may find that wiggling wires around the regulator
may bring it back to life, thats one way of showing up bad
solder joints.
You need a decent voltmeter to do even rudimentary
trouble shooting. They are available cheap from Radio Shack
and other sources. You don't need anything fancy. You may
find that a modern meter will read higher than the voltages
in the chart for the receiver. That's because the meter used
by Hammarlund, and specified by them, has rather low
resistance compared to a modern meter so it affects the
readings more.


--

--
Richard Knoppow
Los Angeles
WB6KBL





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