[Amps] Link coupling

[R.Measures]

On Jan 9, 2005, at 10:42 AM, Rob & Terri Sherwood wrote:

> What is being recommended here?   A grounded secondary center tap or 
> what?  Yes I do get static build up when there are summer thunder 
> storms nearby or even snow static build up in the winter on my 40 
> meter EDZ.   I am not sure what is being implied by "the big bang".   
> Causing an lightning strike due to the way the tuner is or is not 
> grounded?

Terri --- During an electrical storm, a charge slowly builds up on the 
antenna.  When the potential reaches the breakdown V,  a sudden 
discharge occurs and the process starts over.  High-ohm resistors bleed 
the charge off steadily so nothing arcs.

> R. Measures wrote:
>
>>
>> On Jan 9, 2005, at 12:04 AM, G3rzp at aol.com wrote:
>>
>>> The problem with the fixed link and varying secondary turns is that 
>>> you  need
>>> the secondary impedance to vary. There's some compensation in that 
>>> as the
>>> number of secondary turns drops, the leakage reactance tends to 
>>> increase.
>>>
>>> The problem with all of these tuners is that it's quite hard to 
>>> control the
>>> working Q value. Too high a working Q pushes up the losses. Double 
>>> the working
>>>  Q, all other things being equal, and you double the circulating 
>>> current,
>>> pushing  the losses up by 4 times. Swinging links work by varying 
>>> the leakage
>>> reactance,  so you get a wide range of secondary impedances with 
>>> hopefully, a
>>> controllable  Q.
>>>
>>> One thing I don't like about the Matchbox, and that is the lack of a 
>>> DC
>>> ground on the antenna for bleeding static away.
>>
>>
>> The trouble with a direct ground on a balanced feedline is increased 
>> risk of sudden discharge -- as in "big-bang".  To reduce this risk, 
>> slowly bleed down the static charge with  a 1-10 M-ohm HV-type 
>> resistor from each side of the feedline to ground.
>>
>>>
>>> ...
>>
>>
>> Richard L. Measures, AG6K, 805.386.3734.  www.somis.org
>>
>>
>
>
>

Richard L. Measures, AG6K, 805.386.3734.  www.somis.org