> From: Rich Measures <measures@vc.net>
To: <amps@contesting.com>
> Date: Thu, 10 Jul 97 12:39:24 +0000
> >My question was"does the TL-922 use a series or parallel filament
> >circuit?". You stated the only difference was the transformer
> >"style".
> >.
> - I measured the inrush current in each tube with a HP 1708 oscilloscope.
> Did you? It matters not whether the filaments are fed in series with
> 10v or in parallel with 5v. What matters is the measured inrush current
> in each filament. The SB-220 is within Eimac specs. The TL-922 is not.
I take your response as indicating the filament circuits are indeed
different. The TL-922 places the filaments in series, much as the
filament surge prone All American Five radios used, where you could
watch some tubes light up like a spotlight.
In a series system, ESR has half the limiting effect. Worse than
that, the series connection results in poor voltage distribution
during heating with the weakest tube dissipating the highest inrush
power.
Your conclusion the difference doesn't matter is wrong, it makes a
great deal of difference. Series connected filaments in Christmas
Tree lights are bad enough, with $150 tubes a series filament
system is VERY poor engineering, inrush limited or not.
> BTW, Mr. Rauch, I'm still waiting for you to publish the letter that you
> alleged restores Mr. Miklos to the position of "R+D Engineering Manager"
> at Eimac's Salt Lake City facility---a position that their personnel
> department said he did not hold during his employment.
Anyone wishing to see a copy of this letter, which proves Mr.
Measures lives in his own world where he simply "invents things", is
welcome to ask for a fax copy.
>. ..... As I
> recall, you stated that Mr. Miklos was going to show up here In January.
Mr. Miklos, the former director of R+D at Eimac-Varian in Salt Lake
City, is active on internet now Rich. I have no control of his
activity, but it is clear after he read a few of your poison pen
posts he decided to stay far away from you.
Scratch one very useful guy to all of us (except you) on this
reflector.
For an example of why someone might avoid contributing, we need
only look at the long drawn out SB-220 transformer nonsense.
Anyone curious should look at the ARRL Handbook's section on
transformers (page 6.45 of the 95 edition). It plainly states
"Leakage inductance acts in exactly the same way as an equivalent
amount of ORDINARY inductance in series with the circuit." There is
NO current limiting in a transformer, other than conventional losses
that behave EXACTLY like reactances and resistances in a conventional
circuit. Core saturation is a function of applied VOLTAGE, not load
current (unless the load is a rectified system that magnetizes the
core, lowering inductance).
While the Handbook isn't always correct, this information can
also be found in Electronic Designer's Handbook and ITT's Reference
Data for Radio Engineers. When three reference books agree, and
one person is out on his own limb, it isn't hard to understand
where the error is.
I discussed the filament transformer issue at length many years
ago with Ernie Smith, the chief engineer for one of Heath's and
Zenith's main transformer vendors. There is NO special design of the
220 transformer. It's not on the BOM's, it's not "hidden" in
secret papers at the transformer company. It was never spec'ed,
because all that is ever necessary is to build the transformer and
other components out of high temperature materials and run them close
to the design limit.
The repetitious drawn out arguing about the 220 transformer, from a
person who never had access to Heath engineering data or BOM's, just
wastes everyone's time.
So it "looks like" a neon sign transformer, which limits current by
winding ESR and not magnetic shunts, to you. And you are welcome to
think all transformers limit current by core thickness, even though
they do not.
And it doesn't look like a welder transformer to you, which often
DO have a magnetic shunts calibrated in amperes to vary the
leakage impedance and adjust current. You are certainly entitled to
your personal opinion on that also.
No matter how backwards you have things.
73, Tom W8JI
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