[Amps] 3-500 to 4-250 conversion

[Jim Garland]

Hi Kennon,
On the face of it, anyone who would build an amplifier using six 3-500zs, and then proceed to burn out all the tubes, pretty clearly wasn't knowledgable about the rudiments of power amplifier design. There's no way I can think of to make such an amplifier work on 10m, and probably not on any hf band above 160m, and maybe not even there. My advice is to scrap out the amp for the parts and turn elsewhere for advice about sound amplifier design practices.
73,
Jim w8zr

Sent from my iPad
> 
> Date: Wed, 15 Feb 2012 23:58:49 -0800
> From: kennon lewis <saveatpharmacy at gmail.com>
> Subject: [Amps] 3-500 to 4-250 tube conversion
> To: amps at contesting.com
> Message-ID:
>        <CAEgwGaZQj9zXX5t5j995DyTL+q7kJv1+RNTqWue4KnTtioEmKQ at mail.gmail.com>
> Content-Type: text/plain; charset=ISO-8859-1
> 
> hello. recently I received an amplifier with 6 bad 3-500z tubes in it. i
> have a bunch of good 4-250 and 4-400 tubes on hand and am looking to
> convert the amp to run on these tubes. the cost of purchasing 6 new 3-500
> tubes is out of the question at this time. the amp covers 10 - 80 meters.
> looking at the tube data it looks like all i need to do is strap pins 2 and
> three together with a low ohm resistor and that should do the job, one
> being a triode and the other a tetrode. the power supply seems more than
> adequate. any schematic help or other information will be greatly
> appreciated. thanks ke5rgm
> 
> 
>