[Boatanchors] ongoing Johnson adventure

[Bill Cromwell]

Hi,

I started looking in my junk drawers and found a brand new in the 
wrapper 1 meg pot. The shaft is obviously too long. I know what to do. 
Measure twice and cut once. Both grandfathers and my dad told me about 
that along with Mr Osborn - my shop teacher.

I think some of the transitors you can harvest from the curly-que CFL 
bulbs are up to the task. I'll have to look again. I have the power FETs 
in several different flavors here as well as bipolar transistors that 
are capable. Maybe I will install one of these and when the new 5 watt 
wirewound pot arrives I'll set it aside as spare for one of the other 
boatanchors. I still haven't unbuttoned the Ranger to find where the 
smoke is coming from. It would be sweet it just cremated a spider or 
something.

73,

Bill  KU8H

On 02/11/2017 11:10 AM, Robert Nickels wrote:
> On 2/11/2017 7:22 AM, Rob Atkinson wrote:
>> Bob,  What are these tv or power transistors I often hear about?  Are 
>> they
>> still in production?  Do you have any model numbers that can be
>> searched?  What transistor terms am I searching for?
>
> Hi Rob,
>
> I got to thinking about using a power FET instead and found that 
> someone has already done that, and since FETs are more akin to vacuum 
> tubes I like this method better.   The STM part shown is overkill, 
> with an 800V 11A rating,  but it's $5.57 from Digikey. Cheaper 
> N-channel Power MOSFETs with sufficient voltage and current ratings 
> should be fine.
>
> Here is a snippet showing the driver pot replacement from the Johnson 
> Ranger redesign by WA4DSP:
>
> http://i.imgur.com/gVP91ui.png
>
> 73, Bob W9RAN