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Re: [Amps] Alpha 87a

To: Tom W8JI <w8ji@w8ji.com>, g3rzp@g3rzp.wanadoo.co.uk,Steve Thompson <g8gsq@eltac.co.uk>, amps@contesting.com
Subject: Re: [Amps] Alpha 87a
From: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Reply-to: g3rzp@g3rzp.wanadoo.co.uk
Date: Tue, 2 Jan 2007 13:07:35 +0100 (CET)
List-post: <mailto:amps@contesting.com>
Tom said:
>That theory absolutely does not work.<
Well, I only quote the man. Regrettably, he is SK, so we can't ask 
him............
However, depending on the class of operation of the amplifier, there will a 
greater or lesser degree of harmonic energy in the cathode current pulses: a 
low Q network can reduce these, but the effects on measured SWR will be there. 
When we used slotted lines (remember them?) at UHF, they had tuned detectors, 
so wouldn't have that problem. Not very practical at HF......The driving 
transceiver should, (if it meets modern requirements) have harmonics at least 
-50dB down, so the harmonics from the driver are unlikely to be the cause of 
the SWR reading - which as Tom says, can indicate a poor SWR when it's actually 
a good one.
73
Peter G3RZP
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