Mike,

Looks like you are making some progress here.  As for putting a buffer 
between radio and amp:  If you are thinking about something like the 
Ameritron RB-704, it won't help here.  The 704 is for the keying line to 
isolate the radio and amp so a low voltage, low current amp keying relay 
in a newer radio can deal with  an older amp with different electric 
requirements, or just to keep the 2 isolated for piece of mind.  It's 
not  for limiting RF power to the amp, that is what people use  the ALC 
connection for.   Not sure if your radio  or amp  have ALC.

I guess with a radio capable of 200 watts out, you should be very 
careful.  I know the Yeasu is your "dream radio", but maybe you should 
just leave it set at alow drive and use the amp as needed.   Always 
going back and forth between200 watts and low power for the amp, I know 
I would  forget to make the change sooner or later and suffer the 
results.

73, SteveKW3A


On 4/7/2014 1:33 PM, Michael Ryan wrote:
> 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
>
>
>