[time-nuts] 6CW4 Nuvistors on eBay...

[J. Forster]

And the 7587 even has a plate cap! LoL.

There might be RF chokes in the Nuvistor filament line. Worth a look.

FWIW,

-John

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

> Indeed there are.
> And even 7587s thats the TRF frontend. In one of the units V3 appears bad
> all Rs are good voltage high on plate, 0 cathode current. But oddly when I
> swap v1 into position same effect so somethings odd. Or my methods not
> correct.
> The other units working. Had to replace a shorted 6.2 V zener.
> The 100 kc vco /lock osc is awful touchy.
> Pretty amazing the units pretty hot sensitivity wise -80 dbm.
> Interesting afternoon. Way in the deep corner of the basement I think I
> may
> have a nuvistor or two. Time to see what they are.
>
> On Sun, May 2, 2010 at 4:14 PM, Burt I. Weiner <biwa at att.net> wrote:
>
>>
>> For what it's worth, I just took a look and found a bunch of 6CW4's on
>> eBay.  See:
>>
>>
>> http://shop.ebay.com/i.html?_adv=1&_nkw=6CW4+Nuvistor&_in_kw=1&_ex_kw=&_sacat=See-All-Categories&_okw=6CW4+Nuvistor&_oexkw=&_udlo=&_udhi=&_ftrt=901&_ftrv=1&_sabdlo=&_sabdhi=&_samilow=&_samihi=&_sadis=200&_fpos=Zip+code&_fsct=&LH_SALE_CURRENCY=0&_sop=12&_dmd=1&_ipg=50
>>
>> Burt, K6OQK
>>
>>
>>  From: paul swed <paulswedb at gmail.com>
>>> Subject: Re: [time-nuts] schematics for a HP117a please
>>>
>>>
>>> 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
>>>
>>
>> Burt I. Weiner Associates
>> Broadcast Technical Services
>> Glendale, California  U.S.A.
>> biwa at att.net
>> K6OQK