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Fairbanks Morse Model 8a Problem
#3

(update: I restored your deleted thread and answered before I discovered your other thread. I have merged both into this reopened thread.)

Answering your first post first...

It sounds like you have an issue with your intermediate (RF) coil(s).

Let's look at the schematic.
http://www.nostalgiaair.org/pagesbymodel...005757.pdf

Do you have any plate voltage at the 6K7G RF tube (far left on the schermatic)? Your symptoms indicate there is no plate voltage here, which could be causing the plate voltage to rise on your other tubes since it isn't drawing any plate current.

The set of coils connected to band switch section 5C are suspect. Check that voltage and get back with us.

Normally, if you're connecting an antenna lead to the plate of the 6K7G, you're applying high voltage B+ to that antenna lead...don't ever do that...shock hazard! Icon_eek But if the B+ isn't getting to the 6K7G, then the problem must be in those coils connected to band switch section 5C, as stated earlier.

Now, let's examine the issue of the antenna and ground leads. The antenna lead should connect to band switch section 5B as shown on the schematic (see link above). If this set had a ground lead, it would be connected to the chassis at any convenient point.

--
Ron Ramirez
Ferdinand IN


Messages In This Thread
Fairbanks Morse Model 8a Problem - by bm071 - 01-15-2016, 09:23 AM
RE: Fairbanks Morse Model 8a Problem - by Ron Ramirez - 01-17-2016, 08:56 AM
RE: Fairbanks Morse Model 8a Problem - by bm071 - 01-18-2016, 09:24 AM
RE: Fairbanks Morse Model 8a Problem - by bm071 - 01-18-2016, 09:40 AM
RE: Fairbanks Morse Model 8a Problem - by bm071 - 01-18-2016, 07:37 PM
RE: Fairbanks Morse Model 8a Problem - by bm071 - 01-20-2016, 09:19 AM
RE: Fairbanks Morse Model 8a Problem - by bm071 - 01-20-2016, 05:55 PM
RE: Fairbanks Morse Model 8a Problem - by bm071 - 01-20-2016, 05:59 PM



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