[TMC] XFK - AC leakage to chassis

[John Poulton]

After a long hiatus, I've been scanning TMC drawings again, currently the
B-size A- drawings (Assemblies) up to about 1957 so far.  Just happened to
notice

http://tmchistory.org/tmc_drawings/drawings_db/a/a-300-399/a-366a.pdf

While this drawing is fairly plain, some of the assembly drawings are works
of art.  TMC had an amazing drafting department, run by Joe de Greco in the
50's, whose initials are on thousands of drawings..

Roy and Nick: Congrats on a remarkable bit of detective work on the heater!

73, John K4OZY





On Sat, Aug 1, 2020 at 3:05 PM Nick England <navy.radio at gmail.com> wrote:

> Preliminary results are that Roy gets a gold star on his report card.
> I disassembled the heater and ran it for a while - I now have a toasty warm
> block of aluminum and my Simpson 260 doesn't budge when measuring from
> aluminum to AC line.
>
> In case you are curious, here's what the innards look like:
> http://www.navy-radio.com/rtty-keyer.htm#oven
> That's a thermostat next to one of the two 600 ohm/20w heater elements.
>
> If this problem rears its ugly head in the future, I'll swap out the
> crystal oven heaters and try them - unfortunately that involves removing
> the power transformer whose terminals are buried beneath other
> wiring.......
>
> Thanks to all,
> Nick England K4NYW
> www.navy-radio.com
>
>
> On Sat, Aug 1, 2020 at 1:05 AM Roy Morgan <k1lky68 at gmail.com> wrote:
>
> > It’s also possible now that I think about it, that the heater you have
> has
> > gotten damp, and running it for a while would drive out moisture that Is
> > causing the leakage you detect.
> >
> > > On Aug 1, 2020, at 1:00 AM, Richard Knoppow <1oldlens1 at ix.netcom.com>
> > wrote:
> > >
> > >    Is it possible the heating elements are the same, that is could you
> > put the good one in the 200Khz oven?
> > >
> > > On 7/31/2020 6:57 PM, Nick England wrote:
> > >> I started to resurrect an XFK and before applying power checked for
> > >> possible leaky AC line bypass caps - Uh oh - measure about 50K ohms
> > from AC
> > >> line to chassis.
> >
> > Roy Morgan
> > K1LKY since 1958
> > k1lky68 at gmail.com
> >
> >
> >
> >
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