----- Original Message -----
From: "Peter Chadwick" <g3rzp@g3rzp.wanadoo.co.uk>
To: <amps@contesting.com>
Sent: Thursday, September 27, 2007 8:57 AM
Subject: Re: [Amps] New SB-200 owner
> It seems to me we can boil down this discussion to that given:
> 1. you have an SB200 available to convert for 6m
> 2. it is ONLY going to be on 6m
> 3. No way is it going to have any other band on it
> then go ahead, do it properly, a pi network on the output with external
> filters (or even internal if they will fit) and it appears that
> performance will be at least acceptable.
> If, on the other hand, you are starting from scratch to build a 6m
> amplifier, then 572Bs are not the best tube of choice, and there are
> better approaches. I suspect a 3-500Z is one of them.
> 73
> Peter G3RZP
I agree with all except the last sentence in part. The 3-500Z is a great
tube on 6M and well within its 120 MHz maximum ratings. One 3-500Z will
roughly equal a pair of 572B's in output and have better IMD which is
inherent in the design.
However a new Chinese 3-500Z is roughly twice the cost of two 572B's and
will require more PS expense as well.
I wouldnt be bothered building from scratch unless I had a well stocked junk
box or lived in a country with only locally produced parts available at
reasonable cost.
Now if I had the option between buying a $300-350 SB-200 or a $450-500
SB-220 and could afford the difference I would choose the SB-220 every time
just for the low cost 3dB. That would be cheaper than stacking another 8 el
yagi as far as TX performance is concerned, at least in my case.
Carl
KM1H
Carl
KM1H
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