Well just one O those days. Heavens knows why but I had 7 nuvistors and I don't have any idea when I picked them up. 6CW4s and a few other types. But lo and behold one 7587. Plugged in getting signal and osc locked. Its definitely not a hot tube but it proved the tube was indeed the issue. Checked several ugly looking caps but they were actually good. ESR and value. Will replace any how so I can cause myself some real trouble. Thanks
On Sun, May 2, 2010 at 6:01 PM, J. Forster <[email protected]> wrote: > 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. > _______________________________________________ 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.
