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 <[email protected]> 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 <[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 _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
