Dick,
Thanks for the reply.... indeed I misspoke on the plate tuning cap - it is
the Cardwell and it is 9-45pf.
There was no mention of reducing turns on the filament choke in either
article I had been looking at - how many and are you sure this is necessary?
Plate RFC is rewound per a K8SMC article which specifies 42 turns #16. I had
to use a hollowed out wood form over the ceramic one that Health has - it
has been cool so I believe that is not a problem.
please see my other responses to the other gentleman that wrote.
g.
----- Original Message -----
From: "Dick Hanson" <dick@dkhanson.com>
To: "'Gary Myers'" <garymyers@powerc.net>
Cc: <amps@contesting.com>
Sent: Saturday, January 22, 2011 3:17 AM
Subject: RE: [Amps] Help with HL2200 6 meter conversion
> Morning, Gary.....
>
> First of all, congrats on your project!
> Glad to see more folks out there willing to do conversions etc to get more
> db on six.
>
> From what you've said, and by the choice of your plate tuning cap, you
> still
> have too much minimum C.
> A 100pf variable is likely to have a minimum C of around 10-15pf, which is
> just too much.
> If you have a means to check the cap, do so, and I'll wager that you'll
> find
> your lowest reading (installed in the amp) is simply too much.
>
> There are a number of physically smaller caps available that are made by
> the
> same mfger of your caps now that would be a much better choice.
> For example, the Cardwell 154-11-1 is a good choice. It has a max C of
> about
> 45pf.
> Remember, your tubes contribute 10-12pf each to the plate C.
> I would think that your plate tune C, at resonance, will be only 7-10pf
> assuming a loaded Q of 12 or so.
>
> The Cardwell unit can be made to go lower on minimum C by removing a
> couple
> of rotor plates.
> I have used this cap in numerous six meter amps with excellent results.
> These caps sell at Dayton for $20 on average.
>
> My suggestion is to get the plate tank resonant first and then fiddle with
> the parasitic chokes.
> You may well find that what you have presently is fine once you get your
> tank resonant and the efficiency up.
> You haven't mentioned any changes to the filament choke; have you removed
> some of the turns on this choke?
> Also, have you changed the plate RFC?
>
> I'm sure Carl and some others who do these conversions for a living will
> chime in after a bit, so you will get some more help on this.
>
> I've got a number of those Cardwell caps should you decide to pursue a
> physically smaller and electrically smaller plate tune cap.
>
> Good luck,
> Dick, K5AND
> Austin, TX
>
>
>>
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