[Amps] 2m Linear Amp Enquiry

[jeff millar]

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 at thersgb.net>
>To: <amps at contesting.com>
>Sent: Thursday, September 09, 2004 4:50 PM
>Subject: [Amps] 2m Linear Amp Enquiry
>
>
>  
>