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. > _______________________________________________ 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.
