[time-nuts] UPDATE: HP 5300B - HP 5308A Counter Time Base...
kb8tq at n1k.org
Sat Nov 1 21:50:00 EDT 2014
If the OCXO was not heating, it would be off by about 20 to 60 Hz. It’s close enough that it is getting power and heating up. If it does move when you fiddle the trimmer, that part is likely still connected.
It sounds like the beast has simply aged further than it’s trim range.
> On Nov 1, 2014, at 8:39 PM, Burt I. Weiner <biwa at att.net> wrote:
> The closest it will adjust is -2.5 Hz of 10.0000 MHz. This unit differs from the one in the manual in that it has a Microsonics OCXO with the adjustment on the side of the module. The oven does not feel warm but is written on the side is: "Adjust at 25 Deg C", which is about 77 degrees F. The schematic associated with the oven is missing from the schematic. I suspect that the oven is either shot or not getting power. The unit will not power up with the boards separated so I'm going to have to spend some time hanging wires out the side to make measurements. Does anyone know of a schematic showing the Microsonics module and the associated circuitry for oven control? Not sure if it's worth the effort, but it would be a shame to toss it - that's against my nature.
> Burt, K6OQK
>> Tom & Bob,
>> Thanks for the comments and quick reply. Tom,
>> when I originally did a google search I did not
>> see the site that you sent, but from your
>> guidance I did find the manual showing the
>> frequency adjustment and I'm letting the
>> 5300B/5308A combination counter heat up. From a
>> cold start it's about 6+ Hz low when compared to
>> my house GPS reference - a DATUM 9390-52054.
>> In a bit I'll give the thing a tweak and it
>> should come right in as Bob suggests. I don't
>> know the history of this counter except that the
>> fellow that gave it to me has nothing to really
>> compare it against nor the experience to question
>> its accuracy. On my unit the oscillator
>> adjustment marking is gone, but the hole for the
>> adjustment thankfully is still there :>
>> I'll let you know how it goes - should be a simple tweak.
>> Thanks Guys,
>> Burt K6OQK
>> >From: "Tom Miller" <tmiller11147 at verizon.net>
>> >Subject: Re: [time-nuts] HP 5300B - HP 5308A Counter Time Base
>> >Hi Bert,
>> >The service manual for the 5300B is on the keysight.com site under manuals.
>> >http://www.keysight.com/main/techSupport.jspx?s earchT=5300B&id=5300B:epsg:pro&pageMode=OV&pid=5300B:epsg:pro&cc=US&lc=eng
>> >Do you have a frequency reference (house standard) that you can use to
>> >adjust the reference in the counter? See the manual.
>> >From: "Burt I. Weiner" <biwa at att.net>
>> > >I was recently given a HP-5300B / 5308A counter. I thought it might be
>> > >handy when I'm at an AM broadcast transmitter and need to make "rough"
>> > >frequency measurements. It turns out that at 1000 kHz it reads about 4.5
>> > >Hz high. Looking inside I'm not sure if there's a time base adjustment. I
>> > >looked at the on-line manuals available and I don't find any reference to
>> > >adjusting the time base frequency. Does anyone here know anything about
>> > >these counters? Is there a schematic available? I'm not looking for
>> > >precision, but 4.5 Hz at 1 MHz seems a tad much.
>> > >
>> > > Burt, K6OQK
>> > >
>> >From: Bob Camp <kb8tq at n1k.org>
>> >4.5 Hz at 1 MHz is 4.5 ppm. ThatÃ¢ÂÂs not out of
>> >the likely adjustment range on the basic crystal
>> >reference on a 5308. ItÃ¢ÂÂs probably a simple
>> >tweak to get it back into calibration.
> Burt I. Weiner Associates
> Broadcast Technical Services
> Glendale, California U.S.A.
> biwa at att.net
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