I believe Ian to be correct As I also have built a late version of the 432
k2riw amp as well as the last version os the 2 meter amp imported by Down
East using a pair of 4cx400"s. this metal work was by Gorden high precision
of GB. I am still running both amps. I did extensive research prior to
building both amps. I consider Ian as a expert resource on this series of
amps
Regards Sam kf4yox
----- Original Message -----
From: "Ian White GM3SEK" <gm3sek@ifwtech.co.uk>
To: "Carl" <km1h@jeremy.mv.com>
Cc: <amps@contesting.com>; "Ken" <kenw2dtc@comcast.net>
Sent: Tuesday, April 21, 2009 2:39 PM
Subject: Re: [Amps] RE K2RIW 2 Meter Amp.
> Carl wrote:
>>----- Original Message -----
>>From: "Ken" <kenw2dtc@comcast.net>
>>To: "Ian White GM3SEK" <gm3sek@ifwtech.co.uk>; <amps@contesting.com>
>>Sent: Tuesday, April 21, 2009 12:45 PM
>>Subject: Re: [Amps] RE K2RIW 2 Meter Amp.
>>
>>
>>> "for the record, did you guys really mean a 2m - repeat, 2m - version
>>> that
>>> was designed, built and published by K2RIW himself?"
>>>
>>> No, I don't think K2RIW ever designed and built one. The following
>>> PDF file
>>> shows that W2GN actually designed the 2 meter version based on the
>>> K2RIW 432
>>> design. Beware that the PDF file is over 7MB in size and after the
>>> download, it takes another 2 minutes for format the file for your
>>> screen.
>>> The PDF is highly detailed for those who want to build the
>>> "K2RIW/W2GN" 144
>>> mhz amp.
>>>
>>> http://www.newsvhf.com/2m_stripline.pdf
>>>
>>> 73,
>>> Ken W2DTC
>
>>Then Im mistaken on the source as I built a 2 x 4CX250B 2M amp in the
>>mid to late 60's. It was long before Freds ARCOS version.
>>
>>Carl
>>KM1H
>
> There were many push-pull 4CX250B designs around for 2m at that time,
> but K2RIW seemed to be the first to tame the parallel connection using a
> wide stripline. That was a half-wave line for 432MHz in the familiar
> 12in box.
>
> K2RIW's articles were published in 1972. Not long afterwards, QST had a
> photograph of a 2m version that someone had made, with a half-wave line
> in a loooong box; but as far as I know it was W2GN who re-engineered it
> as a quarter-wave for 2m (also borrowing from an 8877 design by Meade).
>
> Fred then designed the complete ARCOS line of VHF/UHF amps using the
> same basic metalwork for all bands, 50 through 432MHz. This included
> some minor re-engineering of the K2RIW to make the grid and anode
> circuits tune more easily.
>
> The designs for 50, 144 and 220MHz were published in 'Ham Radio' around
> 1977 but the 432MHz design wasn't. The 432MHz details eventually
> appeared in 'The VHF/UHF DX Book' with permission from Fred's widow.
>
> (For complete disclosure, I was also involved in the final batch of 2m
> amplifier kits from the UK that were sold through Down East Microwave in
> the mid 90s. I still have the prototype with a pair of Svetlana
> 4CX400As.)
>
>
>
> --
>
> 73 from Ian GM3SEK
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