[TowerTalk] Shunt fed tower 2

[K4SAV]

One other item regarding phasing two different type verticals. The phase 
of the current in the shunt fed tower will not be what you expect due 
the matching network. You have to know the phase of this current to get 
the two verticals working properly.

I guess there are a few choices:
1. Analysis the heck out of the tower with NEC (this will be complicated 
and not likely to produce an accurate answer unless you include every 
associated wire and antenna).
2. Set up the gain and front to back experimentally using field strength 
measurements.
3. Build it, then play around with phasing and see if you can get any 
front to back, or see what seems to work best.  This may take a while, 
and is unlikely to produce good results.

It can be done, but it's not going to be easy.

Jerry, K4SAV

K4SAV wrote:

>..."Above the top at 35 feet is a triband.  I have a wire spaced 1 foot 
>from the tower and attached at the 30 foot point.
>I feed it at the bottom with coax and many radials.  On 80 cw with 50 
>watts I work into europe.  On 40 cw with 50 watts I have worked into the 
>Indian Ocean.  I am assuming it works on transmit or propagation was 
>good.  But on receive it is a dog.  A real failure.
>
>Compared to an off center fed 33 foot vertical (WD9AHH 73 magazine aug 
>1981) the vertical is supperior in signal strength received."....
>--------
>
>I assume you are talking DX here and not local stations. If that 
>vertical receives more signal strength that your shunt fed tower, you 
>have something wrong with your tower. Then the vertical should also be 
>better on transmit. Is it?
>
>For receiving purposes signal to noise ratio is the parameter of 
>interest (not signal strength).  For transmit purposes the received 
>signal strength is the parameter of interest (not the S meter level of 
>the noise).
>
>If you have a wide disparity between these two antennas for 
>transmitting, I would fix that before trying to phase them.
>
>Jerry, K4SAV
>
>
>p.haire wrote:
>
>  
>
>>Thanks for the info on shunt tower.
>>
>>I am 70 and retired.
>>
>>A few years ago I cut my vintage Rohn fold over tower from 50 feet to 30 feet so I could manage it better.
>>
>>Above the top at 35 feet is a triband.  I have a wire spaced 1 foot from the tower and attached at the 30 foot point.
>>I feed it at the bottom with coax and many radials.  On 80 cw with 50 watts I work into europe.  On 40 cw with 50 watts I have worked into the Indian Ocean.  I am assuming it works on transmit or propagation was good.  But on receive it is a dog.  A real failure.
>>
>>Compared to an off center fed 33 foot vertical (WD9AHH 73 magazine aug 1981) the vertical is supperior in signal strength received.
>>
>>I want to use the tower and vertical in a phased array using discimilar verticals (Yardley Beers W0JF QST oct 1977).
>>
>>Before I go on I want to make sure the tower will not weaken the performane over the complete array.
>>
>>I am beginning to think it is best to go with some of the suggestions or a helical end loaded horizontal.
>>
>>Any suggestions or thoughts about the tower?
>>
>>Paul    WA5MUE
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>> 
>>
>>    
>>
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