[time-nuts] AN/URQ-13 FE-15a oscillator question

Fri Feb 12 21:53:21 UTC 2021

Hi

According to table 1-2 in:

http://www.navy-radio.com/freq/urq-eimb.pdf <http://www.navy-radio.com/freq/urq-eimb.pdf>

The URQ-9 and URQ-10 both were rated for 0 to 50C.

Per:

http://www.navy-radio.com/freq/urq23-MIL-T-28816.pdf <http://www.navy-radio.com/freq/urq23-MIL-T-28816.pdf>

The URQ-23 was rated for 0 to 50C

I’d say it’s a pretty likely that the URQ-13 was rated to operate over
0 to 50C. It went into the same locations and did the same thing as the
other devices.

Bob

> On Feb 12, 2021, at 1:07 PM, paul swed <paulswedb at gmail.com> wrote:
> 
> Well there is no doubt someone has been deep into this unit. Hint missing
> screws internally.
> But appears both heater windings are ok.
> So inner and outer oven has a new meaning. I typically understood this to
> be one oven in another oven. Think the HP CS units of old. The same in
> other places HP3801.
> But in the URQ13 it means there is a long tube. The Dewar flask. The inner
> is deep into the flask and the outer is close to the opening. Two
> completely separate heaters. Under the outer heater I will guess is the
> actual oscillator for the 5 MHz. Further out from the outer heater are the
> offset variable caps thermistor for the outer oven a pot and IC.
> Several screws hold this outer heater on and considering the risk of taking
> out the remainders to look and draw a schematic.
> Regards
> Paul
> 
> On Fri, Feb 12, 2021 at 11:28 AM paul swed <paulswedb at gmail.com> wrote:
> 
>> Yes Bob they could get hot. But the radio rooms I have been in circa 1970s
>> were all air conditioned from destroyers to aircraft carriers. Shirt
>> sleeve. The best place to actually be when we were down by the equator was
>> the radio room, ET shop, CIC and radar and just maybe the Captain's
>> stateroom. But if you were actually there you might still be sweating.
>> Chuckle.
>> This conversation has given me some good insights. Later today I will
>> disable the outer oven. Just curious to see what possible temps might show
>> up. Is the inner oven simply reading outer oven leakage. Is there a lead I
>> can measure the current of the inner oven....
>> Thanks
>> 
>> On Fri, Feb 12, 2021 at 11:18 AM Bob kb8tq <kb8tq at n1k.org> wrote:
>> 
>>> Hi
>>> 
>>> If it’s 105F “outdoors” that’s 40C. Military gear back in the days of the
>>> URQ10
>>> did not live in air conditioned enclosures. It did get deployed to places
>>> with
>>> temperatures at or above that level.
>>> 
>>> If it’s 40C outdoors, by the time you get to a pile of electronics gear
>>> *indoors*,
>>> a >10C rise is pretty likely. That drives a very common 50C “upper end”
>>> temperature
>>> on ground gear in relatively benign installations.
>>> 
>>> This does not just apply to military gear. If you look through test
>>> equipment
>>> catalogs, a lot of test gear also has the same sort of 50 to 60C upper
>>> end spec.
>>> The 5065A has a spec of 0 to 50C. The 5061A has the same spec. Both
>>> targeted
>>> pretty “normal” environments …. ( = they never get below freezing …) and
>>> date
>>> to the “era” of the URQ10.
>>> 
>>> In this era of HVAC everywhere, the 5071A has a temp range of 0 to 55C.
>>> If
>>> anything, this would suggest that things still can get pretty hot.
>>> 
>>> Bob
>>> 
>>>> On Feb 12, 2021, at 10:29 AM, paul swed <paulswedb at gmail.com> wrote:
>>>> 
>>>> Bob
>>>> OK there is the math. and that all starts to line up.
>>>> So most likely for other URQ units there will be an ambient max in the
>>>> spec's. At least on the URQ10 in real life even in the hot tropics the
>>>> radio room was shirt sleeve temps.
>>>> But the question asked was 110 F correct as measured on the outside of
>>> the
>>>> outer oven against the dewar flask correct. It isn't. The darn thing is
>>>> reasonably stable though.
>>>> Since the front panel test switch is not labeled I speculate that the
>>>> position for the outer oven is in the normal range. The next switch
>>>> position most likely is inner and is not in the correct position. It
>>> slowly
>>>> moves to the high side.
>>>> No real details on anything and a total guess.
>>>> Really appreciate the thoughts.
>>>> Regards
>>>> Paul
>>>> WB8TSL
>>>> 
>>>> On Fri, Feb 12, 2021 at 10:18 AM Bob kb8tq <kb8tq at n1k.org> wrote:
>>>> 
>>>>> Hi
>>>>> 
>>>>> Indeed the outer oven (as a minimum) needs to be 5 to 10 C above
>>>>> the maximum ambient. If it’s not it goes out of regulation (runs away)
>>>>> and you loose any benefit from it. ( = it now works against you ).
>>>>> 
>>>>> The inner oven as a minimum needs to be 5 to 10 C above the outer
>>>>> oven. Again if it is lower, you can / will get into the same runaway
>>>>> issue.
>>>>> 
>>>>> Those offsets are dependent on the way things are insulated. If you are
>>>>> using a dewar flask, 5C is probably not going to work for you.
>>>>> 
>>>>> Your inner oven *also* is impacted by the turn temperature on the
>>> crystal
>>>>> being used. This *might* have a 20C range. That would put the maximum
>>>>> inner oven temperature at 10 + 10 + 20 = 40C above the maximum ambient.
>>>>> 
>>>>> Needless to say, if the max ambient is 85C, this will get the inner
>>> oven
>>>>> components up pretty hot. That’s not a real good idea. Derating the
>>> heater
>>>>> is pretty easy, derating *everything* in there is much more complex.
>>> You
>>>>> do not often see 85C upper end double ovens ….
>>>>> 
>>>>> One *could* also ask: “is all this worth it?”. List members *have*
>>> written
>>>>> papers addressing that point :)
>>>>> 
>>>>> Bob
>>>>> 
>>>>>> On Feb 11, 2021, at 10:05 PM, Paul Alfille <paul.alfille at gmail.com>
>>>>> wrote:
>>>>>> 
>>>>>> Shouldn't the outer oven be cooler than the inner oven except during
>>>>>> warmup? I would think the inner electronics would be generating heat.
>>>>>> 
>>>>>> Paul Alfille K1PHA
>>>>>> 
>>>>>> On Thu, Feb 11, 2021 at 9:30 PM paul swed <paulswedb at gmail.com>
>>> wrote:
>>>>>> 
>>>>>>> 50C is what I have sort of seen over the years. Just wondered could
>>>>> there
>>>>>>> have been a lower temp version. That made no sense. But then this
>>> beast
>>>>> has
>>>>>>> never made a lot of sense. The $20 mystery from Frequency
>>> Electronics.
>>>>>>> Thanks Bob
>>>>>>> Paul
>>>>>>> WB8TSL
>>>>>>> 
>>>>>>> On Thu, Feb 11, 2021 at 8:08 PM Bob kb8tq <kb8tq at n1k.org> wrote:
>>>>>>> 
>>>>>>>> Hi
>>>>>>>> 
>>>>>>>> Even for an outer oven, anything below 60C / 140F would be low
>>> enough
>>>>> to
>>>>>>>> run into significant problems. On a mil device, an upper end
>>>>> temperature
>>>>>>>> on
>>>>>>>> the equipment likely would be over 70C. The outer oven would need
>>> to be
>>>>>>>> 5 to 10C above that.
>>>>>>>> 
>>>>>>>> Bob
>>>>>>>> 
>>>>>>>>> On Feb 11, 2021, at 5:55 PM, paul swed <paulswedb at gmail.com>
>>> wrote:
>>>>>>>>> 
>>>>>>>>> OK I have had several responses and 110F is low as I expected.
>>>>>>>>> Wonder if I am being faked out? Perhaps by an inner oven and I am
>>> only
>>>>>>>>> reading the outside of the outer oven. The Older URQ10 and newer
>>> URQ23
>>>>>>> do
>>>>>>>>> have 2 ovens. The meter switch for test is only labeled 1-9. no
>>> other
>>>>>>>> clues
>>>>>>>>> to the function. I noticed 2 positions change with warm up. Sort of
>>>>>>>>> supports the 2 oven theory.
>>>>>>>>> Really do not want to take what might be the outer oven off to put
>>> the
>>>>>>>>> probe in.
>>>>>>>>> Thanks everyone.
>>>>>>>>> Paul
>>>>>>>>> WB8TSL
>>>>>>>>> 
>>>>>>>>> On Thu, Feb 11, 2021 at 5:32 PM Bob kb8tq <kb8tq at n1k.org> wrote:
>>>>>>>>> 
>>>>>>>>>> Hi
>>>>>>>>>> 
>>>>>>>>>> 110 F makes very little sense unless you are in a very cold
>>> climate.
>>>>>>>>>> For military gear (or any gear for that matter) 43C on the oven
>>> just
>>>>>>>>>> doesn’t work.
>>>>>>>>>> 
>>>>>>>>>> 110 C would make sense in a very high temperature environment.
>>>>>>>>>> (think of 85C upper end ….).
>>>>>>>>>> 
>>>>>>>>>> Bob
>>>>>>>>>> 
>>>>>>>>>>> On Feb 11, 2021, at 2:18 PM, paul swed <paulswedb at gmail.com>
>>> wrote:
>>>>>>>>>>> 
>>>>>>>>>>> Hello to the group.
>>>>>>>>>>> I have had a AN/URQ-13 or FE-15a oven oscillator for years.
>>>>>>>>>>> Its never worked correctly and in reality some early alpha build.
>>>>>>>> (Funny
>>>>>>>>>>> that its labeled 15a)
>>>>>>>>>>> Looking online there is no documentation that I have been able to
>>>>>>> find
>>>>>>>>>> over
>>>>>>>>>>> the years.
>>>>>>>>>>> However in another discussion on a AN/URQ-23 that does have a
>>> manual
>>>>>>>> and
>>>>>>>>>>> schematics I realized my guesses on power could be totally wrong.
>>>>>>> Using
>>>>>>>>>>> voltages like the URQ23 the URQ13 actually behaves fairly well. I
>>>>> was
>>>>>>>>>> lucky
>>>>>>>>>>> that I didn't destroy something with my original guess.
>>>>>>>>>>> That said what I find odd is the internal crystal oven runs at
>>>>>>> exactly
>>>>>>>>>> 110
>>>>>>>>>>> degrees. Its repeatably warms to that level with a range of
>>> supply
>>>>>>> from
>>>>>>>>>> +/-
>>>>>>>>>>> 12-15V.
>>>>>>>>>>> Does 110 degrees F make any sense at all?
>>>>>>>>>>> Thank you
>>>>>>>>>>> Paul
>>>>>>>>>>> WB8TSL
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>>>>>>>>>> 
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