Pardon my ignorance, but I was under the impression that we, as hams, are
entitled to a maximum of 1500W input power; maybe 2000W or so in the States.
What is all the talk on the monster transformers doing here on a ham related
forum?
Alex 4Z5KS
-----Original Message-----
From: amps-bounces@contesting.com [mailto:amps-bounces@contesting.com] On
Behalf Of Ian White GM3SEK
Sent: Sunday, March 01, 2009 10:17 AM
To: amps@contesting.com
Subject: Re: [Amps] "Big Iron" transformer source in UK?
DAVE WHITE wrote:
>Folks
>For any UK-based people on the list, this firm appear to be a good
>source for custom-wound transformers: http://www.jmstransformers.co.uk/
>They recently quoted me GBP 525 (plus the dreaded 15% tax, unless you
>can claim it back) for 4.5kv at 10kvA. That's by far the cheapest
>quote I had recently. They can turn around orders in a week or so, but
>do a maximum of about 5kV which is fine for my purposes.
>DOES ANYONE UK-BASED KNOW OF ANY OTHER GOOD SUPPLIERS?
There are two in: http://tinyurl.com/ukcomponents (go to the page and
use your browser to find "transformers").
SP Wound Components are excellent for small custom transformers - they
made the multi-winding transformers that we used to supply for the
Tetrode Boards, and are still happy to make one-off special orders.
Their limit is about 1kVA.
Harrison & Greenwood are more comfortable with larger transformers
(presumably you got quote from them?).
A couple of points to the group: transformer manufacturers tend to use
the "kVA" rating as a headline figure to indicate the overall
size/weight; but that rating is for a resistive load. It is not
meaningful for our kind of load involving a rectifier and capacitor
filter. For good HV regulation in a real-life amplifier, we need
transformers with a much higher "headline" kVA rating than the rectified
DC output.
Thanks again to Steve G8GSQ for the link to the "PSU Designer" program
by Duncan Munro M0KGK. When the transformer manufacturer comes up with a
design proposal, you can use PSUD to check how it will perform in a
real-life PSU.
--
73 from Ian GM3SEK
http://www.ifwtech.co.uk/g3sek
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