That begs the question, why is the bios not staying stable?
Its not the tubes, its what is ruining the tubes.
I have never used the ft-102, but I have used the ft-101. Not sure how
different they are, but might be a lot.
The ft-101 did not use 6146 finals, as I recall.
With those PI networks, its not the output that is critical, but having the
final tuned to resonance.
Nobody will ever hear the difference between 185 watts and 140 watts output.
-----Original Message-----
From: For blind ham radio operators [mailto:[log in to unmask]]
On Behalf Of Michael Ryan
Sent: Wednesday, December 03, 2014 7:18
To: [log in to unmask]
Subject: Tubes
Howard:=20
If you read through NC4L Mal's web pages devoted to the 102, the blown =
fuse issue indicates a run away in the tubes. Once this starts, the grid =
screen becomes contaminated and weak.=20 The 6146W has a plate dissipation
of 25W and I have been pushing them a = little harder, tuning up to the
102's maximum 185 key down.=20 I should have kept it back a little to the
300MA current level instead = of 350 and limit things to no more than 150W
key down, using the 2 times = the plate dissipation as a max.=20 However
that's what Mal recommends and standbys them due to the enhanced = vibration
handling capability of the W. This tube was meant for the = mobiles back in
the 50s/60s.=20 There's another camp however that stand firm about using the
6146B. Its = an older tube that has a higher plate dissipation of 35W.=20
Now RF Parts carry the Taylor 6146B in a matched set of 3 and I'm = thinking
of giving those a try if nothing else, they will give me a = higher headroom
for tuning. =20 I use a TW-1 for this and even though there's a couple on
this list who = don't like them, I don't think that there's that big a
discrepancy to = cause tube damage. In fact, my TW-1 corresponds with the
meter in my =
986.=20
As for the receiver, the FT-102 can run circles around the IC-756 Pro = III,
TS-950 with a blocking dynamic range of 130DBM and a 3RD intercept = point
of 19DBM. Not quite as good as the IC-7600 and FTDX series but = when it can
beat the TS-950 and IC-756 Pro III, 20 years behind them, = that's
something.=20 I have found that listening to my 102 the past 2 1/2 years,
I've gotten = a new appreciation for a good quality receiver and I really
don't think = anything is available in the 2K range. I've heard the
IC-7700/800 on you = tube and with the speaker that was used, it came pretty
darn close to my =
102.=20
Its worth your while to google NC4L's 102 site and have a read. Then =
you'll know why I love this radio so much. Its probably like your Drake.=20=
I'm pretty sure there are times when your drake probably beats = everything
in the shack but its the convenience of simply pressing a = button and
hearing everything you need to hear with regards to settings = and so on.=20
73:=20
Mike VO1AX=20
-----
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