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Re: [Amps] Alpha 8410 -- The Market should be D.O.A.

To: Peter Voelpel <df3kv@t-online.de>
Subject: Re: [Amps] Alpha 8410 -- The Market should be D.O.A.
From: Scott McGrath <mcgrath@fas.harvard.edu>
Date: Wed, 04 Jun 2008 21:30:51 -0400
List-post: <amps@contesting.com">mailto:amps@contesting.com>
Commercial practice STILL uses tubes for 1KW and above.    I have a Icom 
2KL which works nicely IF the SWR is less than 2:1 - IT NEEDS its 
companion AT-500 (which I also have) to keep it happy   Also have a 
Harris AM-7223 and a Collins 30-S1 both the Harris and the Collins will 
load up into a bedspring without a external tuner the Harris will tune 
automatically the collins we do the old fashioned way.     I think tubes 
will be around for a while yet until truly HV junctions can be devised 
at a economical cost at which point the impedance mismatch issue will 
become moot and hollow state devices will pass into history

Part of the issue here is that SS finals are designed to load up into a 
50 ohm characteristic impedance ONLY where a tube anplifier is designed 
to compensate for a complex impedance and it considers the antenna 
system as part of the tank circuit since the tube can handle the high RF 
voltage created by a impedance mismatch it is possible to tune the 
circuit until it comes into resonance and a reasonable impedance 
value.    Since the transistors junctions cannot handle a high RF 
voltage the protection circuits need to reduce power until the reflected 
voltage is within the junctions ability to handle the voltage.



Peter Voelpel wrote:
> It depends on the antenna if a tuner is necessary at all.
> I never needed a tuner except on open wire feeders.
> My IC-2KL is happy with all my antennas. It cuts back a little bit of power
> at the band edges, but nobody will recognize whether I run 400 or 600W.
> Anyway, I would not buy a transistor amp with real power, still prefer tubes
> with handles
>
> 73
> Peter
>
> -----Original Message-----
> From: amps-bounces@contesting.com [mailto:amps-bounces@contesting.com] On
> Behalf Of Roger (K8RI)
>
> You need to add the auto tuner to that to get the complete price which will
> bring it up about $1200 more or a total of $7,000 for a rugged, well
> protected, instant on, easy to operate, amplifier with automatic band
> switching.  
>
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