[Antennas] Johnson Tuners

[Les Severson]

Hi Brian,

I suppose it all depends on the design of the link coupling.. I think
you are right when you say "sometimes they're not as efficient"
Having had similar home brew rigs as your Eldico in the old days,  I 
never noticed much loss of power through plug in Bud or Johnson coils..
I imagine a swinging link coil could be better for optimum efficiency.

I still think that a link coupling tuner could be just as efficient as
a pi-net tuner.. especially one using a rotary inductor and a balun.
I cannot provide statistics but I know baluns are fussy and at times 
lossy.  I have also read that roller inductors are not the best
for good positive contact at all times.

I know someone out there has efficiency statistics and arguments both 
ways.  I'm not an RF engineer.
I just know what has worked well for me for the past 50 years.. hi

Thank you for your comments Brian.  I read with great interest your 
contributions to the lists.

73 to all,   Les,  W�OJH

-----------------------------------------------------------

Brian Carling wrote:

> 
> 
> Probably because they are sometimes not as efficient. Link coupling in final 
> amplifiers can tend to be inefficient unless you get all the values right on each 
> band. I had an Eldico transmitter with an 807 final and link-coupled out put. I never 
> could get more than a few watts out of it. I changed the tank to a pi network, and 
> immediately the output soared to over 30 watts.
> 
> I can't say what those 4:1 baluns will do to the efficiency, but as you say, they 
> have to be a weak link in the chain for a matching network too.
> 
> 
> 
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