[Amps] Sb200 plate impedance

[Fuqua, Bill L]

    Plate impedance varies so much with drive, supply voltage etc. That is why we have knobs.
I remember in my younger days, did not worry so much about what it actually was but tapped
the tank coil where it worked best and seemed to have a good Q (selectivity). 
  But those were the old days. Now it seems that folks want an exact answer for something
that is not so exact. 
  One day I needed to quickly build a simple plasma generator source for a Physics demo.
I got a reasonably gaped variable capacitor from the junk supply and would a coil with some
#12 wire. We had some 13.56 packed crystal oscillators and I simply ran it thru a CMOS buffer
and into the gate of a IRF520 FET. The drain simply went to a single loop at the ground end
of the coil and to +supply, bypassed naturally. 
  Had a small fluorescent bulb handy and lit it right up. My associate engineer was quite amazed that
I had not made any calculations and that the single loop of wire worked. In his mind the few inches of
 wire in the link coupling was a short. I then needed a tuning indicator and got a NE-2 from old stock
and soldered the two leads together and then the hot side of the tuned circuit. Again, my associate 
did not understand how that worked either. I just told the professor to tune the capacitor for max
glow of the NE-2 and he was ready to demonstrate the device. We had a partly evacuated sealed 
glass tube, and the small fluorescent bulb to demonstrate the device. They could observe the
spectra produced by them with the simple hand held spectrometers. They were simply of 
cardboard tubes with a slit on one end and a piece of a CD as a grating. The aluminum coating
was removed from the CD.

73
Bill wa4lav
 
________________________________________
From: Amps [amps-bounces at contesting.com] on behalf of Carl [km1h at jeremy.mv.com]
Sent: Sunday, February 16, 2014 4:08 PM
To: Ian Swain; Amps at contesting.com
Subject: Re: [Amps] Sb200 plate impedance

Under what conditions?

At 2400V at 500 ma it will be tween 2800-2900 Ohms depending on the several
formulas use.

I keep it simple and for a SSB linear divide the voltage by the current and
mulyiply by 1.7 which is a K factor based upon class of operation.

Carl
KM1H


----- Original Message -----
From: "Ian Swain" <insane.swain at gmail.com>
To: <Amps at contesting.com>
Sent: Sunday, February 16, 2014 3:14 PM
Subject: [Amps] Sb200 plate impedance


> Crazy simple question I know for most people on this mailing list.
>
> What's the plate impedance on the sb200 ?
>
> Regards ian de zl2ias
> _______________________________________________
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> Amps at contesting.com
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