[Amps] Ten-Tec Centurion

[Bill Coleman N2BC]

Interesting discussion, but has anybody looked at the diagram of the
Centurion?

I had a TT Titan ages ago, it indeed has RF sensing on the input.  But the
purpose was to inhibit RX/TX transfer to prevent hot switching.

Regards,  Bill  N2BC


----- Original Message ----- 
From: "Ian White, G3SEK" <G3SEK at ifwtech.co.uk>
To: <amps at contesting.com>
Sent: Thursday, November 11, 2004 7:53 AM
Subject: Re: [Amps] Ten-Tec Centurion


> R. Measures wrote:
> >> Assuming the spike is at the leading edge of the transmitted signal,
> >>then an
> >> rf sensing circuit could delay the turn on of the rf amplifier until
> >>after
> >> the passing of the spike.
> >
> >Colin -- The problem is that incoming RF does not go on a mini-vacation
> >immediately after the spike, it merely backs down to the ALC level that
> >is set.  Thus, there is RF on the closing NO contacts while they are
> >bouncing.  This results in hot-switching and current-transients.
> >
>
> Also there are two sets of relay contacts, at input and output. These
> contacts will bounce, and even if they are on the same DPCO relay, they
> will not bounce exactly together. This means the PA can have some
> exciting moments when the input relay is closed but the output contacts
> are not. The PA then has full drive but no load, which could lead to
> very high voltages across the tank components.
>
> All of that can happen without any kind of oscillation, either at the
> signal frequency or parasitically at VHF.
>
>
> >>  If that was the case, then the arcing from the
> >> leading edge spike might not occur.  According to the facts given us
> >>by Tom,
> >> he did not experience any arcs while the amplifier was rf sensing.
> >>That
> >> would be one explanation.  It might be the most logical one, too.  It
> >>is a
> >> simpler, less convoluted approach than parasitics.
> >
> >Measuring the actual resistance of the parasitic suppressor resistors
> >and eye-balling their appearance could eliminate parasitics as a
> >possible scenario in under 2-minutes - if the soldering-iron is hot.
> >Not measuring R-supp will not.
>
> Fair point...
>
> I certainly agree about the root cause of the problem, though:
> RF-activated switching will *always* be hot-switching. (And isn't it
> illegal under the anti-CB-amplifier rules?)
>
>
> -- 
> 73 from Ian G3SEK         'In Practice' columnist for RadCom (RSGB)
> http://www.ifwtech.co.uk/g3sek
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