[NJARC] AK89

[Al Klase]

Hi Phil,

OK, it's kinda like being a plumber: Poop flows downhill. Pay day is 
Friday. That's all you need to know.

This is a classic example, so everyone pay attention.

Weak reception from antenna terminal. Stronger reception from first 
detector (mixer, it's a superhet) grid cap.
See: http://www.nostalgiaair.org/PagesByModel/023/M0043023.pdf

What happens if you apply antenna to the RF grid cap?

THE TROUBLE LIES BETWEEN THE LAST PLACE YOU HAVE GOOD SIGNAL AND THE 
FIRST PLACE YOU DON'T. (Moving upstream, as you are doing /signal 
injection/.)

Assuming RF grid cap gives weak performance as well, The trouble lies in 
the RF amp. YOU'VE FOUND THE BAD STAGE.

1. Make sure you have a good tube.

2. FIND THE BAD CIRCUIT (plate, screen grid, grid , cathode.) Measure 
the voltages on the tube pins of the RF amp. Especially look for a high 
voltage to the plate (250 V?) and a somewhat lower voltage (100 V?) to 
the screen.

3. Then turn the set off and use you ohm meter to FIND THE BAD COMPONENT.

ONLY THEN: Try to align the RF stage to a station at the upper end of 
the band. Any tuned circuit you can't peak is suspect.

Regards,
Al






VOURTSIS, PHIL, ATTSI wrote:
> Visit our web site - See http://www.njarc.org
> _______________________________________________
> I just finished restoring an AK89 highboy. I've got the radio working
> nicely but there is one strange thing.
> If I connect an antenna wire at the antenna terminal I get moderate
> volume. But if I connect to the grid cap
> of the 1st detector (35) I get much better reception. I've also noticed
> this on a GE set I worked recently on.
> What would cause this?
>  
> Phil Vourtsis
> Pres.- NJARC
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> NJARC at mailman.qth.net
> http://mailman.qth.net/mailman/listinfo/njarc
>
>
>   

-- 
Al Klase – N3FRQ
Flemington, NJ
http://www.skywaves.ar88.net/