[time-nuts] schematics for a HP117a please

[J. Forster]

Hi Paul,

Some tube testers can test Nuvistors. I don't think they go gassey much,
but with long use the filament emission drops or the filaments go open. So
the condition of yours may depend on how much they were used. They are
normally pretty long lived.

The HP Loop has some gain and is certainly very narrow band. Also WWVB is
not strong or very reliable in the Boston area. It can be a challenge even
with the HP system. I REALLY miss LORAN!!

-John

====================


> Thanks everyone.
> Indeed the nuvistors will be a challenge.
> Don't know if between the 2 recvrs I have enough or if they are good or
> bad...
> But if need be a bit o redesign may be in order.
> I am currently using a fair size copper tune loop/preamp on a tracor 599H.
> So thats a good start. But I will dig in and see whats cooking (Or not)
> Noticed one has the creeping ground lug oxidation. Time for a drill.
>
> Regards
>
> On Sat, May 1, 2010 at 1:02 PM, J. Forster <jfor at quik.com> wrote:
>
>> Have you tried Dave at Artek Media?
>>
>> A couple of things on the 117A:
>>
>> The antenna is a roughly 1 meter diameter loop, but has a very frequency
>> selective pre-amp built in. Early versions used two Nuvistors and a 60
>> KHz
>> mechanical filter. Later versions used FETs I think. The amp in the unit
>> also uses three Nuvistors. These devices are getting scarce and
>> expensive.
>>
>> The coax between thr receiver and antenna has DC on it to power the loop
>> preamp.
>>
>> The paper for the stripchart is getting hard to find also.
>>
>> FWIW,
>>
>> -John
>>
>> ==============
>>
>>
>>
>>
>> > Just picked up 2 units at a flea market today.
>> > Would like to fire them up without smoke. :-)
>> > Would appreciate schematics if the are out there.
>> > My search so far is 0
>> > Thanks
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>>
>>
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>