[time-nuts] HP/Agilent 5065A Rubidium Vapour frequency standard problem - fixed
rfnuts at arcor.de
Sun May 11 13:39:07 EDT 2008
Btw. you don't happen to have a spare green pilot lamp lens, do you?
That's what my 5065A is missing
Roy Phillips schrieb:
> I have just found a 10811-60111, and I am wondering if you or another member
> have the complete schematic for the unit - mine has the PC board #
> 05328-20027, with "fine adjust" pot and C12 &C15 - or is this the normal
> format. I have not yet power it up and have noted the advice about
> ----- Original Message -----
> From: "Palfreyman, Jim L" <Jim.Palfreyman at team.telstra.com>
> To: "Discussion of precise time and frequency measurement"
> <time-nuts at febo.com>
> Sent: Sunday, May 11, 2008 1:18 PM
> Subject: Re: [time-nuts] HP/Agilent 5065A Rubidium Vapour frequency standard
> problem - fixed
>> Thanks folks for all your efforts.
>> It turns out I was right about the 10811. My replacement 10811 fixed the
>> fault but as Chuck pointed out I was being to much of a cowboy with the
>> course adjustment. Instead I tuned the course control of the 10811 to a
>> reference 5 MHz on the bench and then plugged it all in. This time it
>> worked and it stayed working well too! I've been calibrating the C field
>> over the last 12 hours.
>> Now of course I'm turning my attention to the 10811. I would like to fix
>> With the heater off, the oscillator behaves well with the course
>> adjustment providing the appropriate control (haven't check the EFC yet at
>> this temperature). It is of course below 10 MHz. When the heater is
>> powered it does the right thing (0.5 amp for a few minutes then drops
>> back). The frequency rises to a bit over 10.0000 MHz. However the course
>> control no longer has any effect whatsoever.
>> I'm guessing there are some components in the oscillator circuit that are
>> heat damaged after two and a half decades of being in an 82 degree oven.
>> I'm going to follow through the manual and see what I can find.
>> However, if anyone has experienced this pattern before - please let me
>> Thanks again for all your help!
>> Jim Palfreyman
>> -----Original Message-----
>> From: service at frequencystandards.com
>> [mailto:service at frequencystandards.com]
>> Sent: Friday, 9 May 2008 4:00 AM
>> To: time-nuts at febo.com
>> Subject: Re: [time-nuts] HP/Agilent 5065A Rubidium Vapour frequency
>> standard problem
>> You didn't really say in your description but you really need to have the
>> loop open using the front panel switch before you try to adjust the
>> oscillator. Unless you are very familiar with how tiny of a turn it takes
>> to make it too far off to lock, you will have it out of range very
>> quickly. Open the loop and connect the 5Mhz output to a good frequency
>> counter, preferably one that is synched to another rubidium, GPS locked
>> crystal or cesium. Once connected, adjust your crystal coarse adjust for
>> as close to 5Mhz as possible. If you can't get it below a 0.1 hz error,
>> you are going to have trouble getting the unit to lock. Make sure you
>> allow a good warm up time for the crystal in the 5065 before you do any
>> If you can get the crystal to that small of an error, then close your loop
>> and watch the control meter setting. Typical is that the meter will move a
>> small amount but not peg. If it pegs, you have another problem with the
>> unit. If it moves a small amount and stops, you can then adjust the coarse
>> or fine and bring the meter back to zero. If you use the coarse adjust, at
>> this point, you are going to be making VERY tiny adjustments of it.
>> Let us know what you find from this and we can move you to the next step.
>> Chuck Norton
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