[600MRG] Vacuum variable capacitor, low-pass/band-pass filters

[Gedas]

Frank John is spot on.....it ALL depends on the length and configuration 
of your antenna and how much applied power you use. That will determine 
the current & voltages.

if you e-mail me a accurate diagram with dimensions of your proposed 
antenna and how much power you plan to run I will be happy to model the 
system and get you a ballpark value to start out with.

Gedas, W8BYA

Gallery at http://w8bya.com
Light travels faster than sound....
This is why some people appear bright until you hear them speak.

On 6/22/2019 4:45 PM, John Langridge wrote:
>> His reaction was that the voltages for my 630m station
>> couldn't be more than what is seen in AM BC equipment,
> not necessarly true because when we use ohm's law in the reactance
> form, E = IX, X is probably going to be a lot greater in your
> application than in a BC application.  Current will likely be lower
> but consider N1VF's apartment loop.  Ben's Vac Var was seeing about
> 1700 volts for a reactance of about 300 ohms and the current he was
> measuring (I forget how much I without looking and dont have a
> calculator on me at the moment)
>
> I'm not here to say that you can't make it work but just realize that
> you might open yourself to other complications later...
>
> 73!
>
> jl
>
>
>
>
> On 6/22/19, Frank O'Donnell <600 at inkbox.net> wrote:
>> Thanks to everyone for the great responses. Those sound like promising
>> ideas on both the capacitors and filters, and I will check them all out.
>>
>> One question for now. I mentioned my interest in a vacuum variable
>> capacitor to a local ham friend who has a background in the AM broadcast
>> industry. His reaction was that the voltages for my 630m station
>> couldn't be more than what is seen in AM BC equipment, and he thought I
>> might be able to scrounge a cheaper air-dielectric variable cap that
>> would be adequate. Is the preference for vacuum caps due to the fact
>> that they are more compact? Or more available? Or are there other
>> reasons for going with them?
>>
>> Actually, make that two questions for now: Regarding voltages. What sort
>> of voltage rating should I be looking for in any of the caps (variable
>> or fixed) to tune the ~120-foot-circumference vertical loop?
>>
>> Thanks again, and 73,
>>
>> Frank K6FOD
>>
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