Hi Ian,
The 30S-1 L101 is a silver plated inductor. I believe it is used to lower
the effective plate load resistance to allow a reasonable tank Q at higher
frequencies. I did this with a 5CX1500 RF generator (13.56mHz) which I
converted to the ham bands, worked out very well. Used your NETCALC
program a LOT - made things easy!
My implementation is here: http://home.stny.rr.com/n2bc/PT_Project.htm a
page I put together for our club members.
THX for NETCALC!
73, Bill
~~~~~~~~~~~~~~~~
Bill Coleman N2BC
http://home.stny.rr.com/n2bc
----- Original Message -----
From: "Ian White, G3SEK" <G3SEK@ifwtech.co.uk>
To: <amps@contesting.com>
Sent: Sunday, March 23, 2003 4:48 AM
Subject: Re: [Amps] Hard-drive Dive
> 2 wrote:
>
> K7FM had written:
> >>I do have a Collins 30S-1 amplifier. It does
> >>not have parasitic suppressors.
> >
> >** Vern Baumgartner, a friend who worked as an engineer at Collins
> >Radio told me that Ni-Cr alloy was used as a conductor in the
> >4cx1000A's anode circuit.
> >
> Let's be careful with the facts here. Looking at the schematic of the
> 30S-1, there is no conventional R/L parasitic suppressor. There is an
> "L101" between the anode connector and the HV blocking cap, right where
> you would expect a parasitic suppressor to be. The photograph shows a
> substantial inductor of 3-4 turns of thick wire, about 0.75-1in diameter
> and 2-3in long.
>
> This is the only place where it could make any conceivable sense to put
> a parasitic suppressor; but what L101 is made of, the manual sayeth not.
>
> At a glance, there's something connected to the anode called "Z-101"
> that looks like a parasitic suppressor, but it is in the path to the
> capacitive divider that provides RF negative feedback. In that location,
> Z-101 cannot damp the VHF parasitic resonance of the plate circuit.
> However, this deliberate additional RF feedback path will also make the
> 30S-1 behave differently at VHF than amps that don't have this feature.
>
> The 30S-1 is a unique amplifier. It contains many RF, power-supply and
> mechanical features that were highly innovative and individual to that
> amplifier. Some of these features will only work together as a
> "package". Attempts to copy individual aspects have generally not been
> successful, because the copiers weren't as smart as the original Collins
> engineers, and didn't understand how everything interacts.
>
> In short, the 30S-1 is a dangerous precedent for *both* sides of the
> nichrome controversy!
>
>
> --
> 73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB)
> Editor, 'The VHF/UHF DX Book'
> http://www.ifwtech.co.uk/g3sek
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