Thanks Nomad.
yes, i know i had previously been talking all about "fully UNmeshed" positions of the tuning caps, and im guessing that using a different set of tubes is the reason this changed?
IDK.
As of right now, the input tune seems to be good after adding 680pF of capacitance on the switch side of that 47 ohm resistor used for HI and LO power.
putting the amp in LO shorts this capacitor in essence, and input tune is only slightly higher in LO position. below 1.5 so im happy with that.
It seems to me that the owner of this amp probably had it mistuned, based on how he told me he'd "always done it", and my advice of how to tune it seemed to go right over his head.
so he got to ragchewing, with the amp mistuned, which burnt the trace that supplies 12vac to the bias line, which im guessing put the amp into overdrive, super heating the tubes, which caused one of the 100uF HV caps to smoke (they were only about two inches away from the final tubes) and the meter near the driver tube to melt.
the amp wasn't visible to him while talking so im guessing that the meter was melting before the cap went and the plume of smoke is what caused him to shut the amp down.
I have been using his tubes for testing up until today, and they seemed to put out decent power, but maybe there is a characteristic of these tubes that im not aware of where they can be damaged from being operated in that manner while still technically not being "bad".
There is a CB shop in town that has a tube tester, so im going to go down there and have his tubes tested, but the guy that runs it probably won't have any insight for me based on what he sees.
right now im tuning the amp with a set of (mismatched) 6LB6's acquired from ebay and they seem to be working so far and im left wondering if this set of tubes peaks the output tank circuit differently than his 6LF6's.
maybe that's why im talking about meshed instead of UNmeshed at this point.
boy if i haven't muddied the waters yet, i don't know what will LOL.
LC
