[Amps] AL-1200 Pop

[Ed Briggs]

It could be lots of things. But I recently had this problem and it turned
out to be the tube.

Symptoms:  Pop in standby, at power up.
                   Visible flash, apparently coming from RF compartment
                   Occationally, damage to B- clamping diodes.
                   No carbon or other charring

Differential Diagnosis:  Remove tube; apply power.
                                   Never happened with tube removed

Alternative theories:
                   Parasitics
                   Dust, humidity, spiders and other bugs,
                    finger grease on the tube chimney
                    bent chimney clips
                    Cracked or damaged blocking capacitor

Actual Cure:
            Replacement of the tube.

Apparently, Ameritron has seen this before and replaced the tube w/o charge
(under warranty). The tube was returned to Ameriton
for testing and 'tested good' but promptly failed when re-inserted in my
amp. Ultimately, my tube went back to Eimac.

(Yes, I know, you shouldn't have seen a flash for a tube arc, but there was
an arc. It may have been a reflection
of the step start relay arcing, or perhaps the light of the internal arc
through the ceramic)

Happy hunting

Ed


----- Original Message ----- 
From: "Dana Roode" <K6NR at ARRL.net>
To: "AMPS" <amps at contesting.com>
Sent: Sunday, July 04, 2004 9:25 PM
Subject: [Amps] AL-1200 Pop


> I just finished replacing the open frame relay in my old AL-1200 with the
> Ameritron relay PCB mod.  Put it all back together, seemed to work fine,
> tuning on 40m.  Moved to 160m, had the Amp in Standby while I set the
output
> power on the exciter.  Heard a loud Pop - exciter power only.
>
> I turned the Amp off for awhile, then tried it again.  It still works
fine.
>    I opened it up looking for a visibly bad component, none found.
>
> Any ideas what this might have caused a Pop in Standby?  Should I worry?
>
>    Dana
>
> _______________________________________________
> Amps mailing list
> Amps at contesting.com
> http://lists.contesting.com/mailman/listinfo/amps