Re: [Amps] 2m Linear Amp Enquiry

[jeff millar <wa1hco@adelphia.net>]

Pi Net's don't work on 2M, but here's a site that shows how to use HF 
techniques for building 2M PA's

   http://nd2x.net/yu1aw-2m-easy.html

Note he uses the Russian triodes like Jerry suggests.

jeff, wa1hco


Jerry Muller wrote:

> A pi network on 2 meters? Never work.
>
> I've had a couple of tetrode amps for 2, one was the old classic plumbers
> delight push pull amp with a pair of 4CX250s. That worked OK. A much better
> design is a 1/4 wavelength stripline using either 4CX250s or 8930s. That amp
> was sold by ARCOS a few years ago.
>
> The stripline design is better with better efficiency. A problem however is
> IMD with those tetrodes. It's a bit high and those tubes require a fairly
> complex power supply with a screen supply that must not only be capable of
> sourcing voltage, but also sinking it. Negative screen current is normal
> with those tetrode amps. I'd bet the 4CX800s would work well in that
> configuration too.
>
> Triodes are much better. The W6PO amp using the 8877 is an excellent design.
> A similar design could be constructed with the Russian tubes or the Eimac
> triodes like the 3CX800 or 3CX1200. The IMD with these amps is much better.
>
> If you're only operating CW or FM there's not much difference. On SSB the
> triode designs with lower IMD are a far better choice. Your neighbors (hams
> nearby) will appreciate it. On VHF/UHF nearby stations are REALLY loud. The
> tetrode amps will make you VERY wide at your neighbors houses even if you
> run them properly. The high order IMD products (7th, 9th, 11th, 13th) are
> still quite strong when you're 100+ dB above their noise floor.
>
> 73 es GL,
>
> Jerry, K0TV
>
> ----- Original Message ----- 
> From: "David King" <G6KWA@thersgb.net>
> To: <amps@contesting.com>
> Sent: Thursday, September 09, 2004 4:50 PM
> Subject: [Amps] 2m Linear Amp Enquiry
>
>
>  

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