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[AMPS] Re: [Amps] CW Amplifier progress (well, daydream progress) -- lon

To: <amps@contesting.com>
Subject: [AMPS] Re: [Amps] CW Amplifier progress (well, daydream progress) -- long
From: km1h@juno.com (km1h@juno.com)
Date: Wed, 17 Mar 1999 10:14:02 -0500


On Tue, 16 Mar 1999 08:01:08 -0800 Vic Rosenthal <rakefet@rakefet.com>
writes:
>
>Peter Chadwick wrote:
>> 
>> Especially if you're only looking for 1500watts of CW, why not 
>4CX250B's? 4
>> of them, 2kV at an amp or so, and you're there. You should be able 
>to pick
>> them up reasonably cheaply with sockets. Over here, I'd reckon to 
>get
>> sockets and 4 tubes for under $150. 
>
>I thought about this.  My investigations so far haven't lead me to any 
>cheap
>ones.  They may be out there, but the prices I've seen so far have 
>been quite
>high.  Unfortunately, I can't ask for a guarantee on flea-market tubes 
>for an
>amp that I haven't built yet, so I need to get them from a reliable 
>source.
>
>> Do you really need instant on?
>
>I can live without it.  It's just one point in favor of filament-type 
>tubes.  Of
>course, the other side of the coin is that the filament current is 
>higher,
>requiring a big transformer and filament choke.
> 
>> The big advantage of 3-500Zs to my mind is that the blower 
>requirements are
>> such that it's likely to be reasonably quiet.
>
>My SB1000 uses a muffin fan to cool the tube and seems quite noisy.  I 
>would
>like the one I'm building to be quieter.  

QRO seldom is quiet Vic. Of course you can run a YC-156 and a muffin fan
at QRP levels!

The brand new SB-220 fan assy from Harbach is very quiet.

73  Carl  KM1H



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