Topband: Antenna matching question

Tom W8JI w8ji at w8ji.com
Tue Mar 18 21:55:44 EDT 2014


>> If this is only 160-40 you probably won't have a series resonance issue 
>> with unused turns, but if you cover a wide range you will want to 
>> progressively short the large coil taps. This is why band switches that 
>> do not short (like the old National amp) and why large roller inductors 
>> mess up on higher bands.
>
>
> If you mean the NCL-2000 I suggest looking at the schematic again.  Or did 
> National make another ham amp that Ive missed??
>

Here you go, Carl

http://www.arizona-am.net/PHOENIX/W7CPA/W7CPA%20NCL-2000%20BS%20Before.jpg

That's the wrong way to do a bandswitch. It does not pick up and hold the 
lower band contacts when switched to higher bands. This allows the taps to 
build up high voltages on lower band taps when working higher bands.

Switches should be pick up and hold, or progressively shorting.

73 Tom 



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