[Amps] Building or Buying a Tuned Input Network

[w6ah@comcast.net]

Bob

I'm willing to guess that he will tell you the expertise of people working on amps varies widely and those at the bottom end of the spectrum are of marginal competence. If I sell a few hundred complete kits I'm going to have a couple of dozen individuals that will keep me tied up on the phone for 10 to 20 hours a week with customer support issues. In essence I wind up troubleshoot these guys amps from top to bottom on issues unrelated to my product. At 60 bucks for the kit I wind up taking it in the shorts. That was why he suspended production of the kits. He produced the kit as a way to supply a finished PC Boards and critical components to eliminate the grunt work of PC board lay out and etching. As well as reducing the the time chasing after relays and toroidal cores. Designing the circuit and coming up with the caps and wiring should not be that big a deal.

Regarding tuning, with the Q levels as low as they are component selection is not that critical. The circuit is there to present a constant load to the transmitter through out the conduction cycle

73s  

Bob W6AH

-------------- Original message -------------- 
From: "Bob Selbrede, K6ZZ" <k6zz at ccis.com> 

 
> While the tuned input board looks nice, I'm puzzled as to 
> why he doesn't supply it with the mica caps and inductor 
> wire if the application is known at the time of order. 
> Without variable inductors, how would you go about tuning 
> the system in-circuit? I guess you would need to tune it 
> out of the amp by simulating the tube drive impedance and 
> play around with various combinations of L and C until you 
> get a match; install it, and hope for the best? Time for a 
> call to WD7S. 
> 
> Thanks, Bob 
> 
> ----- Original Message Follows ----- 
> From: Bill Turner 
> To: Tony King - W4ZT , 
> amps at contesting.com 
> Subject: Re: [Amps] Building or Buying a Tuned Input Network 
> Date: Sun, 22 Jan 2006 20:14:34 -0800 
> 
> > ORIGINAL MESSAGE: 
> > 
> > At 07:14 PM 1/22/2006, Tony King - W4ZT wrote: 
> > 
> > >Take a look at Paul's (WD7S) tuned input board: 
> > > 
> > > 
> > >73, Tony W4ZT 
> > 
> > 
> > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 
> > 
> > I considered that board but decided against it because 
> > nothing is adjustable except by soldering and unsoldering 
> > capacitors, or by adding/removing turns from the toroids. 
> > 
> > Tony, have you used this board? What are the instructions 
> > regarding tuning? Does it have a chart of suggested 
> > values for the silver mica caps? How close did it come to 
> > reality? 
> > 
> > Bill, W6WRT 
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