Mike,
Until your recent troubles with the amp, I believe your tuner is the problem
which ultimately damaged the amp. Send the tuner to MFJ for repair or sell
it as parts and get another. I don't know anything about that amp, does it
have a tuned input that is 50 ohms that is now damaged and no longer 50
ohms?
Howard #3
----- Original Message -----
From: "Michael Ryan" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Monday, April 07, 2014 12:33 PM
Subject: Re failed tubes
> Hi Lloyd, Steve and all:
> I actually did all those coax jumper and feed line tests, dummy load put
> out at the base of the antenna, a couple of months back when I had my 75M
> SWR spike.
> All the coax jumpers and feed line was good. Its not until my tuner was
> swapped out for a friends that the problem went away. That same friend
> took my tuner apart and discovered some damage to the roller inductor and
> capacitor. He cleaned it up as best he could and once again we tried it
> out.
> Worked flawlessly handling 200W but caused a Hiss in the amp when I
> attempted 500W. Now earlier today, I had a chat with the friend who has my
> amp and apparently he did the SWR test between rig and amp this morning
> and discovered an 8/1 SWR on all bands and a group of blown resisters.
> The thing is, the amp gave no sign of this on friday night on 75/40M, no
> hissing, cracking or smells what so ever, I ran my usual 600W.
> John, this amp has a separate band coil for 40, 75, 160 and one for 30/20,
> one for 17/15 and I believe one for 12/10 but not sure as this position on
> the band switch is marked aux.
> You place the amp on this setting for 10/12M providing the mod is done. I
> didn't tune up there to see if the mod was done because I don't operate on
> those bands.
> I think its starting to look like this amp just had bad tubes but we'll
> see what happens.
> I also can't help but wonder if I shouldn't put a buffer between the 102
> and amp due to the high max power capability of the 102.
> When tuning up, I'd have the amp in standby and would tune up for the
> 102's max power of 180W CW.
> I would then reduce the output to my 20W amp tune up level and go from
> there, finishing with the 75W max drive, then reduced to the 45/50W of
> operating drive. Running the amp at 600W CW with that drive level, 800W on
> SSB.
> Another thing is, my grid and plate would hover between 175/200 and
> 450/600 and wouldn't pin on the numbers, just bounce up and down.
> All these numbers are perfectly fine as long as the needles don't pin on
> 200 and 750.
>
> 73:
> Mike VO1AX
---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com
|