Try as I might, I cannot hear a single thing from my 5065A, which has
run 24/7 for five years without issue.
Jared earlier said he has inverter noise from his 5065A and now Magnus
reports it also. How common is this?
I will be interested in a replacement A15 regulator board as Ulf
Kylenfall
Hi Jared,
One of my 5065's have exactly this fault.
One approach is to rebuild with a new power inverter. Another is to
rebuild the amplifier board so it does not need -20 V and can operate
only on +20 V.
There should be DC-DC inverters, but I failed to grab a suitable
pre-built board for
Jared,
I think an -20 V rail short to ground has first blowup A15Q10.
Then the -20V converter was light loaded and the output DC voltage goes up and
blows also the zeners.
The most easy way to protect and repair: replace A15Q10 with a LM337 with 2
resistors to adjust the output to -20V.
Hi
Since you can “dial in” the correct voltage, I’d go with the parts you
can find. I’d be suspicious that all those parts died and the transformer
is still healthy …..
Bob
> On Dec 2, 2021, at 9:15 AM, Jared Cabot via time-nuts
> wrote:
>
> So it looks like I lost the -20V rail. Seems that
Aha! That is very interesting background information! It nicely puts your
comment in perspective to "bridge the fuse with a wire and be done with it".
Big grin here when reading the "beer was involved" comment. I have used a
similar approach on my business visits to HP CXO (well after T was
Well, it seems more digging is needed... I have 84uA Photo I coming from the
RVFR on A7P1, but the front panel is at 14 (Should be 42 for my Photo I level)
Manual says look at Q1, Q2 and IC1 circuits. Anyone have any pointers or
suggestions on what to check?
Jared.
‐‐‐ Original Message
Don't give up now, Jared! You must be so close to getting that puppy running
correctly.
On 2/12/21 9:16 pm, Jared Cabot via time-nuts wrote:
Well, yay...
I put the OCXO back in the 5065A, and got a good 2nd Harmonic reading. So I
started going through the alignment procedures and somehow I
Well, yay...
I put the OCXO back in the 5065A, and got a good 2nd Harmonic reading. So I
started going through the alignment procedures and somehow I now have no 2nd
harmonic again, and I can't get it back...
I'm starting to lose interest in this thing, seeing as I have the Leo Bodnar
GPS
Hi
The reason for the thermal fuse (which is *not* a feature of other OCXO’s)
is the 10811’s deployment in a wide range of devices. There are a few that
do have restrictions on them. The 5065 is not one of those devices.
The protection provided is minimal. The pass transistor will fail in a
Hi
The last time I went 10811 shopping, I found a seller with a lot of them.
His price was right ($40 each) if you bought a batch at a time. I tested
them all for ADEV / phase noise and the other basic bench stuff. I did
not run any of them over temperature ( but neither did HP …. ).
Net
And I will bet the smell is as bad as the larger 0106 oven. As I say its in
a sealed bag and not sure how I will recover it. Need the windows open.
The suggestion of buying a replacement is the best even if you do need to
buy 2-3 to locate a good one.
Regards
Paul
On Wed, Dec 1, 2021 at 6:13 AM
1 at 7:19 PM
> >
> > From: "Hal Murray" halmur...@sonic.net
> >
> > To: "Discussion of precise time and frequency measurement"
> > time-nuts@lists.febo.com
> >
> > Cc: "Hal Murray" halmur...@sonic.net
> >
> >
Bob L.
> Sent: Tuesday, November 30, 2021 at 7:19 PM
> From: "Hal Murray"
> To: "Discussion of precise time and frequency measurement"
>
> Cc: "Hal Murray"
> Subject: [time-nuts] Re: HP 5065A, no 2nd harmonic.
>
>
> lajeune...@mai
Hi
Guessing at what you are looking at:
Try to look for "teflon standoff" on Google…..
Bob
> On Nov 30, 2021, at 7:19 PM, Hal Murray wrote:
>
>
> lajeune...@mail.com said:
>> Judging from the teflon solder cup used I suspect insulation resistance is a
>> critical parameter.
>
> Could
On 1/12/21 5:03 am, Jared Cabot via time-nuts wrote:
Hopefully I can find something in Akihabara
Yeah yeah, don't rub it in! :^)
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lajeune...@mail.com said:
> Judging from the teflon solder cup used I suspect insulation resistance is a
> critical parameter.
Could somebody please give me a lesson or pointer or ...
I noticed something interesting in the picture. Is that just a ring on the
surface, or a part that drops
S20
Original message From: Jared Cabot via time-nuts
Date: 11/30/21 9:35 AM (GMT-08:00) To: Discussion
of precise time and frequency measurement Cc: Jared
Cabot Subject: [time-nuts] Re: HP 5065A, no 2nd
harmonic. I was reading in a past thread on the time-nuts mailing list
Hi
The thermal fuses die on their own far more often than they die protecting
anything. The fuse is there to provide safety is certain odd situations. The
simple answer these days is to replace it with a piece of wire.
Bob
> On Nov 30, 2021, at 12:05 PM, Larry McDavid wrote:
>
> Do these
Yes the fuses can just fail like any fuse. But with the oven it pays to
very carefully insure they didn't fail because of temp. and that they did
there job.
Regards
Paul
WB8TSL
On Tue, Nov 30, 2021 at 1:09 PM Dan Rae via time-nuts <
time-nuts@lists.febo.com> wrote:
> On 11/30/2021 7:19 AM, Bob
On 11/30/2021 7:19 AM, Bob kb8tq wrote:
Hi
Quick and dirty way to check the oven is to monitor current. It should start out
near the max rated power and drop back after a few minutes.
And it's worth checking the thermal fuse, which I've had fail in a lot
of them.
Dan
I was reading in a past thread on the time-nuts mailing list that the thermal
fuses can occasionally spontaneously go open circuit with age, far more often
than going open due to a real thermal fault.
(I wonder how many have been discarded over the years due to this issue?)
They appear to be
Do these thermal fuses fail spontaneously or is there a common cause?
If the "heater" transistor mounting screws were quite loose, those
transistors themselves might have overheated and failed. But, a thermal
fuse should fail by high temperature...
Sounds like progress, though. Cold OCXO
9:36 AM
> >
> > From: "Jared Cabot via time-nuts" time-nuts@lists.febo.com
> >
> > To: "Discussion of precise time and frequency measurement"
> > time-nuts@lists.febo.com
> >
> > Cc: "Jared Cabot" jaredca...@proton
. Be sure to clean
away any flux remaining after soldering.
Bob L.
> Sent: Tuesday, November 30, 2021 at 9:36 AM
> From: "Jared Cabot via time-nuts"
> To: "Discussion of precise time and frequency measurement"
>
> Cc: "Jared Cabot"
> Su
Hi
Quick and dirty way to check the oven is to monitor current. It should start out
near the max rated power and drop back after a few minutes.
Bob
> On Nov 30, 2021, at 9:36 AM, Jared Cabot via time-nuts
> wrote:
>
> Ok, so I carefully dismantled the OCXO and I may have found the
Ok, so I carefully dismantled the OCXO and I may have found the culprit... The
screws holding the two transistors to the metal body were both less than finger
tight!
Don't know how that happened, so they were cinched up to 5in-lbs with the
torque screwdriver as per the service manual, and I'll
Original message From: cdel...@juno.com Date: 11/27/21 7:04
PM (GMT-08:00) To: time-nuts@lists.febo.com Subject: [time-nuts] Re: HP 5065A,
no 2nd harmonic. Jared,You have to be within .25Hz so yes I'd say that's most
likely
yourproblem!Cheers
Hi,
The electrical tune (fine control knob) is set to midrange now, at the 250
setting. The mechanical tune (the one in the OCXO itself) is maxed to its limit
and I can't raise it further.
My 5335A has the OCXO option, so if it is compatible, I might be able to do a
swicharoo into the 5065A
Hi
Just to double check.
There is an electrical tune (controlled by the multi turn pot) and a
mechanical adjust on the OCXO. The “that needs repair” judgement
is based on both being adjusted to their “max high” setting *and* you
still being ~40 Hz low.
I doubt that you have 40Hz of range
Jared,
You have to be within .25Hz so yes I'd say that's most likely your
problem!
Cheers,
Corby
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To unsubscribe, go to and follow
Hi
Roughly speaking the OCXO is 40 Hz or 8 ppm at the max end of the tune range.
That’s a lot.
If your OCXO is that low, then yes, it is a problem. You either need to repair
or replace
the OCXO. If you are replacing, the question becomes - do you upgrade to a 10
MHz
10811? That would
Jared absolutely thats 40 Hz low. It needs to be about +/-10 Hz or less.
Granted the system has a wider range. For the heck of it can you fairly
easily inject your 5 MHz gpdso 9about 0 Hz off)into what the OCXO feeds.
You only actually need A10j3 marked 1V on the OCXO. You can leave the other
5
Hi,
I have performed the test with the 10Mohm resistor.
With an 0.5V P-P signal from the function generator into A7J1, I get 980mV at
A7TP2 (Manual says it should be about 0.9V)
When I probe the A7 output (Yellow wire) i get a good output as described in
the manual too, so it looks like my A7
Jared
I took a look at the manual and if you inject 137 hz at .5 Vpp through a 10
Mohm R thats in a sheild into A7j1 you will see .9 Vpp at TP2 and some
large signal upto 16 Vpp at Yellow out. That would say the A7 module is
good. It looks like the 2 ICs are lm741 class opamps if they happened to
Hi,
Ok, I managed to get a moment to do a few tests. I'll try to answer the
questions so far, sorry if I miss something out.
For test equipment, I have the following gear of possible use:
- HP 5335A 200MHz Universal Counter with 1.3GHz option
- Leo Bodnar GPS Reference
- HP 34461A Multimeter,
Jared
OK lets start.
Can you share a bit with us please.
Whats types of test equipment do you have.
Believe we will need a scope, DVM (Reasonable grade), audio sig gen,
perhaps a fairly good reference GPSDO. I am coming at this with the
possibility the issue could be anyplace.
The suggestion that
Hi there
I don't have much experience with the HP5065A, but one I did this very
same issue on my Efratom FRK-L. Turns out the thermistor controlling the
resonator cavity temperature was broken and the cavity temperature was
off. This caused loss of resonance lock, and by definition, loss of
Hi
Well backing up a bit, why does a 5065 have a second harmonic?
Very quickly:
The stuff in the physics package creates an absorption notch. You
interrogate this notch with a phase modulated locally generated microwave
signal. When the signal is at the right frequency it dumps photons and
you
List -- I've contacted Dana, Paul, and Jared to find out how this thread
degenerated. There is no reason I can think of for a discussion about hp
5065A, one of the most prized frequency standards in the time nuts
repertoire, to be hijacked or suppressed by anyone on this mailing list.
A
TVB, I'm interested in the nitty-gritty of this problem and would appreciate
it if you OK this thread's being kept on the group.
Dana
On Thu, Nov 18, 2021 at 6:58 PM Jared Cabot via time-nuts <
time-nuts@lists.febo.com> wrote:
> Hi,
> Your help is appreciated. We can keep this on-list for now
Hi,
Your help is appreciated. We can keep this on-list for now I guess, on the
chance it helps someone in the future.
Jared.
‐‐‐ Original Message ‐‐‐
On Friday, November 19th, 2021 at 08:25, paul swed wrote:
> Jared I would be happy to see if I can help remotely. We may want to take
Jared I would be happy to see if I can help remotely. We may want to take
this offline or not. Others may find it interesting.
Regards
Paul
WB8TSL
On Thu, Nov 18, 2021 at 12:56 PM Jared Cabot via time-nuts <
time-nuts@lists.febo.com> wrote:
> Hi all,
>
> I have a 5065A Rubidium Standard that was
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