Topband: 160M/80M Vertical - Using a capacity hat below a trap

[Carl]

I'll try this again as I used the wrong email to reply. km1h at jeremy.mv.com 
no longer exists.

Carl


----- Original Message ----- 
From: "Carl" <km1h at jeremy.mv.com>
To: "rich kennedy" <astro_maryland at yahoo.com>; <topband at contesting.com>
Sent: Wednesday, October 01, 2014 8:48 AM
Subject: Re: Topband: 160M/80M Vertical - Using a capacity hat below a trap


> Whatever is below the trap stays below and affects 80 only. You can add a 
> loading coil, hat, linear loading section, or whatever to shorten the 80M 
> portion and then add more wire or loading coil above the trap for 160.
> It wont take much of anything to make up just 5'.
>
> In more extreme cases realize that shortening increases losses and reduces 
> feed impedance plus efficiency which places more importance on the ground 
> system to keep overall losses tolerable; the hat has the least losses.
>
> Carl
> KM1H
>
>



> ----- Original Message ----- 
> From: "rich kennedy via Topband" <topband at contesting.com>
> To: <topband at contesting.com>
> Sent: Wednesday, October 01, 2014 8:15 AM
> Subject: Topband: 160M/80M Vertical - Using a capacity hat below a trap
>
>
>> I’m finalizing design for my 160M/80M shortened wire tree-mounted
>> vertical.  An Unadilla 80M trap will be
>> placed approx. 65’ feet above the feedpoint; above the trap is another 20 
>> feet
>> with a small cap hat.  An autotuner
>> handles the Z matching for the anticipated 500 watts on both bands.
>>
>> QUESTION: Can one install a capacitive hat directly below
>> the 80M trap to help shorten the length of the 80M section?  For example, 
>> shortening the 80M radiator to
>> 60’ (from 65’) and making up ‘the difference’ with a capacity hat?  Any 
>> downside?
>>
>> NOTE: Please omit suggestions about using a larger hat on
>> 160M (sloping wires, etc.) – I know that it is much more desirable, but 
>> that is
>> just not feasible here at K3VAT.
>>
>> Thanks, 73, Rich, K3VAT
>> _________________
>> Topband Reflector Archives - http://www.contesting.com/_topband
>>
>> -----
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>