[AMPS] Re: Building of First amp - 813

[nasfred@1bigred.com]

Hello John,

W4MB had an article in Ham Radio a number of years back describing the
construction of a amp. with three 813s in grounded grid and I believe it
covered 40 thru 10 meters.  If interested, let me know and I can dig up the
article and send you a copy.

        73,
        Mike, K4GMH

At 04:19 PM 2/11/98 EST, you wrote:
>>  Is there experience here with using 813 in triode connection?
>
>Hello John,
>The 813 is a very rugged tube and has the reputation of being
>almost indestructable in amateur service.  It is common to use it as
>a triode. The main limitation of the 813 in conventional circuits is
>reduced efficiency on bands above 20M.
>
>ZL1AXB has successfully used a circuit which tunes the filament
>and this improves the sfficiency dramatically. This tuned cathode
>network takes the form of a bifilar circuit, and eliminates the
>usual filament RF chokes.  ZL1AXB demonstrates key-down >400W
>output on 10m with a single 813 with Pv of 3000v.
>
>The cathode circuit is described in an *Eimac* amateur service
>newsletter #AS-6 by W6SAI, W6KEV, and W6UOV.  Some of the material
>may have appeared in QST August 1961 p16-21, but I have not checked
>this.
>
>Regards,
>Martin ZL1ANJ
>
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>
	73,
	Mike, K4GMH


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