HP5065A Rubidium questions: some progress
Hi All,
Thank you all for the very helpful suggestions!
I will try to reply to you all in this one post.
I opened up the A12 assembly and was happy to find that the lamp,
windows, and reflector all appear to be in good physical condition.
There is some very light corrosion on the aluminum reflector, all of
the windows are clear, and the photodiode is very visible at the bottom
of the oven.
The Rb bulb looks very slightly darkened, maybe like a pair of very
lightly polarized sunglasses.
I measured the resistance of the 20 VDC supply line to the lamp
oscillator and it is 3350 ohms, just as Corby said and as I see it
should be from the schematic.
I measured the current to the lamp oscillator and it is only about 13
mA. Paul mentioned that if it was about 15 mA it was probably not
working. And, Poul-Henning mentioned that it should draw about 3W when
working, which at 20 VDC would be 150 mA.
I powered up the lamp oscillator with it on the bench and I do not see
any light from the bulb. I am assuming that it should be visible, but
I'm not sure! What is the spectrum from these lamps like? Visible,
UV???
I measured the resistance of the small coil wound around the bulb, it is
about 0.3 to 0.4 ohms, which seems reasonable.
(It looks like someone has been in this assembly before. There is
solder flux on the transistor leads, the 20 VDC connection, and the bulb
coil leads.)
One odd bit is that the resistor in the transistor emitter leg measures
about 350 ohms (this is R3 in my schematic). The schematic says it
should be 10 ohms. This resistor is on solder posts, so it looks like a
'selected at assembly' item. Corby: it this the 12 ohm resistor you
mentioned?
The voltage across this resistor when the power is on is about 1.6 V.
The base voltage is about 2.2 V (this is across CR1 also) and shows
"flat-lined" on my scope with the board powered.
So, I'm betting that the collector of the transistor is cooked. (The
base-emitter drop of ~0.6 V probably means the base and emitter paths
are still OK.)
But, it is also possible that the R3=350 ohms is way out of line??
Comments welcomed.
Corby: the serial number for the unit is 0968A00302. It has a 105-6012
quartz oscillator, and a mechanical PP clock. The A12 unit is a series
1220, and is green in color. (The OCXO and the bands around A12 are
blue.) The A12 unit has a warranty expiration of 30 April 1978. It has
had its "Mag Filed" and "Thumbwheel" blacked out with marker and new
values written in.
Cheers,
Scott
On 2/20/2017 4:25 PM, David Scott Coburn wrote:
One odd bit is that the resistor in the transistor emitter leg
measures about 350 ohms (this is R3 in my schematic). The schematic
says it should be 10 ohms. This resistor is on solder posts, so it
looks like a 'selected at assembly' item. Corby: it this the 12 ohm
resistor you mentioned?
Scott, there's no way that oscillator can deliver the power needed to
excite the lamp with that high an R3. Something like the specified 10
Ohms is needed.
Dan
That actually sounds like good news.
The lamp will light and its a purple orange. Not sure how safe it is to
look at. Hmm but I have carefully.
If you have a scope the oscillator runs at 150 MHz +/-20 MHz its not fussy.
You only need to get the scope probe close to see the RF.
But likely its not running and its down to good old trouble shooting. Not
uncommon to have solder issues. These are old and have been cooked for ages.
May just need some serious TLC.
But you seem to be headed in the right direction.
Regards
Paul
WB8TSL
On Mon, Feb 20, 2017 at 7:25 PM, David Scott Coburn scotttt@optonline.net
wrote:
Hi All,
Thank you all for the very helpful suggestions!
I will try to reply to you all in this one post.
I opened up the A12 assembly and was happy to find that the lamp, windows,
and reflector all appear to be in good physical condition. There is some
very light corrosion on the aluminum reflector, all of the windows are
clear, and the photodiode is very visible at the bottom of the oven.
The Rb bulb looks very slightly darkened, maybe like a pair of very
lightly polarized sunglasses.
I measured the resistance of the 20 VDC supply line to the lamp oscillator
and it is 3350 ohms, just as Corby said and as I see it should be from the
schematic.
I measured the current to the lamp oscillator and it is only about 13 mA.
Paul mentioned that if it was about 15 mA it was probably not working.
And, Poul-Henning mentioned that it should draw about 3W when working,
which at 20 VDC would be 150 mA.
I powered up the lamp oscillator with it on the bench and I do not see any
light from the bulb. I am assuming that it should be visible, but I'm not
sure! What is the spectrum from these lamps like? Visible, UV???
I measured the resistance of the small coil wound around the bulb, it is
about 0.3 to 0.4 ohms, which seems reasonable.
(It looks like someone has been in this assembly before. There is solder
flux on the transistor leads, the 20 VDC connection, and the bulb coil
leads.)
One odd bit is that the resistor in the transistor emitter leg measures
about 350 ohms (this is R3 in my schematic). The schematic says it should
be 10 ohms. This resistor is on solder posts, so it looks like a 'selected
at assembly' item. Corby: it this the 12 ohm resistor you mentioned?
The voltage across this resistor when the power is on is about 1.6 V.
The base voltage is about 2.2 V (this is across CR1 also) and shows
"flat-lined" on my scope with the board powered.
So, I'm betting that the collector of the transistor is cooked. (The
base-emitter drop of ~0.6 V probably means the base and emitter paths are
still OK.)
But, it is also possible that the R3=350 ohms is way out of line??
Comments welcomed.
Corby: the serial number for the unit is 0968A00302. It has a 105-6012
quartz oscillator, and a mechanical PP clock. The A12 unit is a series
1220, and is green in color. (The OCXO and the bands around A12 are blue.)
The A12 unit has a warranty expiration of 30 April 1978. It has had its
"Mag Filed" and "Thumbwheel" blacked out with marker and new values written
in.
Cheers,
Scott
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/m
ailman/listinfo/time-nuts
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Hi Scott,
the emitter resistor have to be in the range 9 to 15 Ohm. Probably the high temperature and current have burned it out.
Replace it with a 12 Ohm 1/2 W resistor, It will work.
Luciano
www.timeok.it
From "time-nuts" time-nuts-bounces@febo.com
To time-nuts@febo.com
Cc
Date Mon, 20 Feb 2017 19:25:37 -0500 (EST)
Subject [time-nuts] HP5065A Rubidium questions: some progress
Hi All,
Thank you all for the very helpful suggestions!
I will try to reply to you all in this one post.
I opened up the A12 assembly and was happy to find that the lamp,
windows, and reflector all appear to be in good physical condition.
There is some very light corrosion on the aluminum reflector, all of
the windows are clear, and the photodiode is very visible at the bottom
of the oven.
The Rb bulb looks very slightly darkened, maybe like a pair of very
lightly polarized sunglasses.
I measured the resistance of the 20 VDC supply line to the lamp
oscillator and it is 3350 ohms, just as Corby said and as I see it
should be from the schematic.
I measured the current to the lamp oscillator and it is only about 13
mA. Paul mentioned that if it was about 15 mA it was probably not
working. And, Poul-Henning mentioned that it should draw about 3W when
working, which at 20 VDC would be 150 mA.
I powered up the lamp oscillator with it on the bench and I do not see
any light from the bulb. I am assuming that it should be visible, but
I'm not sure! What is the spectrum from these lamps like? Visible,
UV???
I measured the resistance of the small coil wound around the bulb, it is
about 0.3 to 0.4 ohms, which seems reasonable.
(It looks like someone has been in this assembly before. There is
solder flux on the transistor leads, the 20 VDC connection, and the bulb
coil leads.)
One odd bit is that the resistor in the transistor emitter leg measures
about 350 ohms (this is R3 in my schematic). The schematic says it
should be 10 ohms. This resistor is on solder posts, so it looks like a
'selected at assembly' item. Corby: it this the 12 ohm resistor you
mentioned?
The voltage across this resistor when the power is on is about 1.6 V.
The base voltage is about 2.2 V (this is across CR1 also) and shows
"flat-lined" on my scope with the board powered.
So, I'm betting that the collector of the transistor is cooked. (The
base-emitter drop of ~0.6 V probably means the base and emitter paths
are still OK.)
But, it is also possible that the R3=350 ohms is way out of line??
Comments welcomed.
Corby: the serial number for the unit is 0968A00302. It has a 105-6012
quartz oscillator, and a mechanical PP clock. The A12 unit is a series
1220, and is green in color. (The OCXO and the bands around A12 are
blue.) The A12 unit has a warranty expiration of 30 April 1978. It has
had its "Mag Filed" and "Thumbwheel" blacked out with marker and new
values written in.
Cheers,
Scott
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
Totally agree with the try a 12 ohm resistor. Nice simple and low risk.
If thats actually the issue then you do need to obtain a high quality
resistor that can live in a hot environment. Anything will work for a test
run.
Regards
Paul
WB8TSL
On Tue, Feb 21, 2017 at 2:22 AM, timeok timeok@timeok.it wrote:
Hi Scott,
the emitter resistor have to be in the range 9 to 15 Ohm. Probably the
high temperature and current have burned it out.
Replace it with a 12 Ohm 1/2 W resistor, It will work.
Luciano
www.timeok.it
From "time-nuts" time-nuts-bounces@febo.com
To time-nuts@febo.com
Cc
Date Mon, 20 Feb 2017 19:25:37 -0500 (EST)
Subject [time-nuts] HP5065A Rubidium questions: some progress
Hi All,
Thank you all for the very helpful suggestions!
I will try to reply to you all in this one post.
I opened up the A12 assembly and was happy to find that the lamp,
windows, and reflector all appear to be in good physical condition.
There is some very light corrosion on the aluminum reflector, all of
the windows are clear, and the photodiode is very visible at the bottom
of the oven.
The Rb bulb looks very slightly darkened, maybe like a pair of very
lightly polarized sunglasses.
I measured the resistance of the 20 VDC supply line to the lamp
oscillator and it is 3350 ohms, just as Corby said and as I see it
should be from the schematic.
I measured the current to the lamp oscillator and it is only about 13
mA. Paul mentioned that if it was about 15 mA it was probably not
working. And, Poul-Henning mentioned that it should draw about 3W when
working, which at 20 VDC would be 150 mA.
I powered up the lamp oscillator with it on the bench and I do not see
any light from the bulb. I am assuming that it should be visible, but
I'm not sure! What is the spectrum from these lamps like? Visible,
UV???
I measured the resistance of the small coil wound around the bulb, it is
about 0.3 to 0.4 ohms, which seems reasonable.
(It looks like someone has been in this assembly before. There is
solder flux on the transistor leads, the 20 VDC connection, and the bulb
coil leads.)
One odd bit is that the resistor in the transistor emitter leg measures
about 350 ohms (this is R3 in my schematic). The schematic says it
should be 10 ohms. This resistor is on solder posts, so it looks like a
'selected at assembly' item. Corby: it this the 12 ohm resistor you
mentioned?
The voltage across this resistor when the power is on is about 1.6 V.
The base voltage is about 2.2 V (this is across CR1 also) and shows
"flat-lined" on my scope with the board powered.
So, I'm betting that the collector of the transistor is cooked. (The
base-emitter drop of ~0.6 V probably means the base and emitter paths
are still OK.)
But, it is also possible that the R3=350 ohms is way out of line??
Comments welcomed.
Corby: the serial number for the unit is 0968A00302. It has a 105-6012
quartz oscillator, and a mechanical PP clock. The A12 unit is a series
1220, and is green in color. (The OCXO and the bands around A12 are
blue.) The A12 unit has a warranty expiration of 30 April 1978. It has
had its "Mag Filed" and "Thumbwheel" blacked out with marker and new
values written in.
Cheers,
Scott
_______________________________________________
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I installed a 10 ohm 1/2 watt carbon resistor and the Rb lamp came right
on! Woo-hoo!
I will get a better quality, high temperature resistor to replace this
one. (RN70?)
How critical is the resistance value? 10 ohm? 12? Is there a way to
test for an optimum value?
Scott
On Tue, Feb 21, 2017 at 10:01 AM, paul swed wrote:
Totally agree with the try a 12 ohm resistor. Nice simple and low
risk.
If thats actually the issue then you do need to obtain a high quality
resistor that can live in a hot environment. Anything will work for a
test
run.
Regards
Paul
WB8TSL
On Tue, Feb 21, 2017 at 2:22 AM, timeok wrote:
Hi Scott,
the emitter resistor have to be in the range 9 to 15 Ohm. Probably
the
high temperature and current have burned it out.
Replace it with a 12 Ohm 1/2 W resistor, It will work.
Luciano
www.timeok.it
From "time-nuts" time-nuts-bounces@febo.com
To time-nuts@febo.com
Cc
Date Mon, 20 Feb 2017 19:25:37 -0500 (EST)
Subject [time-nuts] HP5065A Rubidium questions: some progress
Hi All,
Thank you all for the very helpful suggestions!
I will try to reply to you all in this one post.
I opened up the A12 assembly and was happy to find that the lamp,
windows, and reflector all appear to be in good physical
condition.
There is some very light corrosion on the aluminum reflector, all
of
the windows are clear, and the photodiode is very visible at the
bottom
of the oven.
The Rb bulb looks very slightly darkened, maybe like a pair of
very
lightly polarized sunglasses.
I measured the resistance of the 20 VDC supply line to the lamp
oscillator and it is 3350 ohms, just as Corby said and as I see it
should be from the schematic.
I measured the current to the lamp oscillator and it is only about
13
mA. Paul mentioned that if it was about 15 mA it was probably not
working. And, Poul-Henning mentioned that it should draw about 3W
when
working, which at 20 VDC would be 150 mA.
I powered up the lamp oscillator with it on the bench and I do not
see
any light from the bulb. I am assuming that it should be visible,
but
I'm not sure! What is the spectrum from these lamps like?
Visible,
UV???
I measured the resistance of the small coil wound around the bulb,
it is
about 0.3 to 0.4 ohms, which seems reasonable.
(It looks like someone has been in this assembly before. There is
solder flux on the transistor leads, the 20 VDC connection, and
the bulb
coil leads.)
One odd bit is that the resistor in the transistor emitter leg
measures
about 350 ohms (this is R3 in my schematic). The schematic says
it
should be 10 ohms. This resistor is on solder posts, so it looks
like a
'selected at assembly' item. Corby: it this the 12 ohm resistor
you
mentioned?
The voltage across this resistor when the power is on is about 1.6
V.
The base voltage is about 2.2 V (this is across CR1 also) and
shows
"flat-lined" on my scope with the board powered.
So, I'm betting that the collector of the transistor is cooked.
(The
base-emitter drop of ~0.6 V probably means the base and emitter
paths
are still OK.)
But, it is also possible that the R3=350 ohms is way out of line??
Comments welcomed.
Corby: the serial number for the unit is 0968A00302. It has a
105-6012
quartz oscillator, and a mechanical PP clock. The A12 unit is a
series
1220, and is green in color. (The OCXO and the bands around A12
are
blue.) The A12 unit has a warranty expiration of 30 April 1978.
It has
had its "Mag Filed" and "Thumbwheel" blacked out with marker and
new
values written in.
Cheers,
Scott
_______________________________________________
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To unsubscribe, go to https://www.febo.com/cgi-bin/
mailman/listinfo/time-nuts
and follow the instructions there.
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Great news and what a deal a dead 5065 lives.
I don't think its that critical and not sure how you would test it. But do
get a good stable high temp. As I recall the rn70 series was pretty good.
For the moment you can reassemble it and see if the rest works the resistor
should hold up for a 30 or so minute run. Don't push it if its a plain old
cheapy carbon.
Best of luck, though I think you have had plenty so far.
Regards
Paul
WB8TSL
On Tue, Feb 21, 2017 at 7:56 PM, David Scott Coburn scotttt@optonline.net
wrote:
I installed a 10 ohm 1/2 watt carbon resistor and the Rb lamp came right
on! Woo-hoo!
I will get a better quality, high temperature resistor to replace this
one. (RN70?)
How critical is the resistance value? 10 ohm? 12? Is there a way to
test for an optimum value?
Scott
On Tue, Feb 21, 2017 at 10:01 AM, paul swed wrote:
Totally agree with the try a 12 ohm resistor. Nice simple and low risk.
If thats actually the issue then you do need to obtain a high quality
resistor that can live in a hot environment. Anything will work for a test
run.
Regards
Paul
WB8TSL
On Tue, Feb 21, 2017 at 2:22 AM, timeok wrote:
Hi Scott,
the emitter resistor have to be in the range 9 to 15 Ohm. Probably the
high temperature and current have burned it out.
Replace it with a 12 Ohm 1/2 W resistor, It will work.
Luciano
www.timeok.it
From "time-nuts" time-nuts-bounces@febo.com
To time-nuts@febo.com
Cc
Date Mon, 20 Feb 2017 19:25:37 -0500 (EST)
Subject [time-nuts] HP5065A Rubidium questions: some progress
Hi All,
Thank you all for the very helpful suggestions!
I will try to reply to you all in this one post.
I opened up the A12 assembly and was happy to find that the lamp,
windows, and reflector all appear to be in good physical condition.
There is some very light corrosion on the aluminum reflector, all of
the windows are clear, and the photodiode is very visible at the
bottom
of the oven.
The Rb bulb looks very slightly darkened, maybe like a pair of very
lightly polarized sunglasses.
I measured the resistance of the 20 VDC supply line to the lamp
oscillator and it is 3350 ohms, just as Corby said and as I see it
should be from the schematic.
I measured the current to the lamp oscillator and it is only about 13
mA. Paul mentioned that if it was about 15 mA it was probably not
working. And, Poul-Henning mentioned that it should draw about 3W
when
working, which at 20 VDC would be 150 mA.
I powered up the lamp oscillator with it on the bench and I do not see
any light from the bulb. I am assuming that it should be visible, but
I'm not sure! What is the spectrum from these lamps like? Visible,
UV???
I measured the resistance of the small coil wound around the bulb, it
is
about 0.3 to 0.4 ohms, which seems reasonable.
(It looks like someone has been in this assembly before. There is
solder flux on the transistor leads, the 20 VDC connection, and the
bulb
coil leads.)
One odd bit is that the resistor in the transistor emitter leg
measures
about 350 ohms (this is R3 in my schematic). The schematic says it
should be 10 ohms. This resistor is on solder posts, so it looks
like a
'selected at assembly' item. Corby: it this the 12 ohm resistor you
mentioned?
The voltage across this resistor when the power is on is about 1.6 V.
The base voltage is about 2.2 V (this is across CR1 also) and shows
"flat-lined" on my scope with the board powered.
So, I'm betting that the collector of the transistor is cooked. (The
base-emitter drop of ~0.6 V probably means the base and emitter paths
are still OK.)
But, it is also possible that the R3=350 ohms is way out of line??
Comments welcomed.
Corby: the serial number for the unit is 0968A00302. It has a
105-6012
quartz oscillator, and a mechanical PP clock. The A12 unit is a
series
1220, and is green in color. (The OCXO and the bands around A12 are
blue.) The A12 unit has a warranty expiration of 30 April 1978. It
has
had its "Mag Filed" and "Thumbwheel" blacked out with marker and new
values written in.
Cheers,
Scott
_______________________________________________
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To unsubscribe, go to https://www.febo.com/cgi-bin/
mailman/listinfo/time-nuts
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