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 <[email protected]>
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 <[email protected]> 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.
[email protected]
K6OQK
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