John Mohn was W5MEU. I remember him talking about that one night over 20
years ago.I have an old 450TL that I want to use. I guess I need to bring
it up slowly with a variac feeding the filament transformer to keep the
inrush current from wrecking the filament, or is that an issue?
Brett,
I'm thinking the thermal cycling, a number of years of use that is for
the most part intermittent, followed by then sitting for another year
and a half has been what broke the back. So long as the intermittent
use was a rather regular periodic interval, I was heating them up and
gettin
I have a modulator that uses four 100TH tubes, it has had the same tubes for
the last 25 years, they look clear, and work fine.
I have a bunch of spare 100 TH and TL's, all look ok last I looked...
I have noticed a bunch of white tubes in the 7 and 9 pin tube stashes, maybe
the seals fail, the p
Sorry Lee!
I've also been putting in some moulding in the house. (Probably
misspelled it too!) It is a Honey-Do day with the wife off.
I'm still trying to figure out why some that sit and have been used,
versus the ones IN the radio that have sat are the ones that are the
ones showing the "g
I think there is at least some truth to this Lee, but I am not sure of why. By
the same token though I have run 250ths for quite some time and with many hours
of no use both winter and summer without air conditioning. They seem to always
work the same even though I may only fire them up once o
John Moan (forgot his call and spelling) (SK) in San Antonio used to run a
few BC-610s. He always rotated his 100TH and 250TH tubes to keep gassing
from forming in them. He had about a dozen BC-610s and around 17 R-390A
receivers in his shack. I think he used to say it was bad to lie them on
Dave,
I was looking at the PA stage in particular at the time.
Mostly I had on just filament. I suspect that these triodes, even on
just filament, probably need a muffin fan or some such, even though
Uncle Sam ran these without any cooling.
I say this because I've got one 250TH sitting in a s
I used to run 304TLs, still want to put something together with a pair of
them, I always did run a small cheap shaded pole fan on them even thou Eimac
did not say anything about doing that, never ran 250 or 100ts, they should
be a lot easier at hi freq than the 304s. I still really like triodes.
Bernie,
That's my take on this too! At least from past experience.
I'm just puzzled by the occurrence. I doubt that there is 25 hours of
actual plate power applied, I.E., key down. I don't make the "old
buzzard" routine talks. I've always been in a round table, most being
technical in natu
John,
I don't get the 250TH to load worth a hoot! The plate voltage is fine.
The drive checks out good back to the pair of 807s. I saw the evidence
of the drive at the grid clip.
The 100THs had been set with the specified mA on the speech amp. I
don't like the PA mA reading so I am hesitan
The milky white appears when the tube has lost its vacuum and fil power is
applied, I have seen this vapor of death more than a few times when testing
old fellows. This is not to say that this is the only reason for the white
deposits, but it is the only way I have seen it form. Bernie W8RPW
---
Do they show color on the plates or gas type ionization color when in use? If
they show gas ionization color when in use then they defiantly have air in them
and could be caused by overheating due to some malfunction. Maybe they have
many more hours on them than you know about. If the plates
Question:
I have noticed that the 100THs and 250THS that are in their original
boxes, either not used at all, or maybe use for less than an hour to
test them, seem to be doing fine.
Their envelopes are crystal clear an can not see any sort of defect.
Then the ones that are in one of the two BC-6
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