Ive always taken it that the traditional 1/4 wave, along with even and odd
multiples, is the classic synchronous version. Results are repeatable.
Carl
KM1H
----- Original Message -----
From: "David Cutter" <d.cutter@ntlworld.com>
To: "Ian White GM3SEK" <gm3sek@ifwtech.co.uk>; <amps@contesting.com>
Sent: Sunday, August 02, 2009 3:16 AM
Subject: Re: [Amps] Asynchronous coax matching transformer
> Would someone please fill me in with the distinction between synchronous
> and
> asynchronous?
>
> David
> G3UNA
>
>
> ----- Original Message -----
> From: "Ian White GM3SEK" <gm3sek@ifwtech.co.uk>
> To: <amps@contesting.com>
> Sent: Saturday, August 01, 2009 8:30 PM
> Subject: Re: [Amps] Asynchronous coax matching transformer
>
>
> K5GW wrote:
>>Hi all,in addition to the examples Larry offered, the scheme will also
>>match impedances less than 50 ohms, down to 22.2 ohms if I remember
>>correctly.
>>
>
> Thanks to Larry and Gerald for pointing out that the series method is
> much more versatile than I had imagined.
>
>>A two way power divider where two 50 ohm loads are in parallel
>>requires a 25 to 50 ohm transformer which is easily handled with the
>>series matching method.
>>
>>The only down side is the difficulty in adjusting the matching sections.
>>On the other hand, transmission line calculations via Smith Chart or
>>computer program will give the exact lengths in degrees needed so
>>tuning is not a real requirement anyway.
>>
> Greg Ordy's program takes care of that, and also says when a match is
> not possible.
>
>>If the sections are joined via coax connectors, you have to take into
>>account where 75 ohms ends and 50 ohms begins. The connectors are
>>invariably of a 50 ohm type and their internal length must be added to
>>the 50 ohm part of the matching section.
>>
>>The last issue is velocity factor of the coax and connectors. A serious
>>builder will be prepared to confirm these quantities before cutting the
>>matching sections to length.
>>
> Connectors wouldn't seem to be a major issue up to 50MHz. Wherever
> paralleled cables are required, I find it easier to not to use
> connectors at all, but to splice the cables by soldering.
>
>>It is a real joy to go through the numbers and have the transformer turn
>>out right on frequency.
>>
> Oh yes!
>
>
> --
>
> 73 from Ian GM3SEK
> http://www.ifwtech.co.uk/g3sek
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