[TowerTalk] Please Help Me Decide on a Tribander or Monobanders

Fri Apr 19 09:53:50 EDT 2013

That is a lame argument to single out a SteppIR as the only antenna that can fail.....

I called a crane in to lift my 20m monobander of a tower to repair element damage after a storm and place it back.

Funny part is a lot if these critics never even owned a SteppIR..... 

Sent from my iPhone

On Apr 18, 2013, at 6:00 PM, "Jim W7RY" <w7ry at centurytel.net> wrote:

> """ Particularly when your buddy with the SteppIR is calling the crane guy to do a repair and you're working the P5. :-)"""
> 
> LOL!!! How true is that! (Ok... Let the flames begin).
> 
> Chris
> KF7P
> 
> 73
> Jim W7RY
> 
> 
> 
> 
> On Apr 18, 2013, at 16:24 , Richard Thorne wrote:
> 
> I sure like my C31XR at 79' with a Delta 240 mounted 10' above it. I plan on changing out the 240 with a Delta 230/240  and lower it to about 7' above the C31xr then add a WARC 2/2 at the 10' level.  That will give me a rotatable 10 through 40 solution.
> 
> I also have a C3 tribander (going on 17 years old) mounted on a rotatable swinging side gate at 40'.
> 
> I really like the F12 antennas, instant band change and made in America.
> 
> Rich - N5ZC
> 
> 
> On 4/18/2013 4:06 PM, Wayne Willenberg wrote:
>> My 86 or 89 foot crank-up tower project seems to be progressing through my
>> County review boards.  So now I am getting really excited for my first
>> tower.
>> 
>> I am now in ham nirvana because I have to start making up my mind on which
>> antenna(s) to put on the 15’ mast.  Here is my first dilemma.  Should I put
>> up a tribander (10, 15 and 20M) or 3 monobanders.  My intuition said there
>> was no way a tribander with the same 20M boom length could beat 3
>> monobanders having a 20M antenna with the same boom length.
>> 
>> So, just as an exercise, I looked at Force 12 antennas.  (I am not
>> endorsing Force 12 antennas, although they do seem to have a good
>> reputation.  I am also aware that the performance specs of antenna
>> manufacturers need to be taken with a grain of salt –this is not meant to
>> be a criticism of Force 12.)
>> 
>> I started with the Force 12 model C-31XR tribander.  It has 14 elements on
>> a boom length of 31’, a wind load of 10.7 sqft and published figures of:
>> 
>> 20M gain: 14.0dBi, a F/B of 20dB,
>> 
>> 15M gain: 14.3dBi, a F/B of 22dB, and
>> 
>> 10M gain: 15.6dBi, a F/B of 21dB.  Published price: $2,970
>> 
>> Then, I looked for monobanders from Force 12 that had a boom length for the
>> 20M monobander close to the C-31XR and a gain in the vicinity of the of the
>> tribander for each of the 3 bands.  Here is what I found:
>> 
>> EF-420 (20M with 4 elements) has a boom length of 30’, a gain of 14.5Dbi,
>> a  F/B of 22dB, a wind load of 5.5 sqft, and a cost of $1,300.
>> 
>> EF-415 (15M with 4 elements) has a boom length of 20’, a gain of 14.6Dbi, a
>> F/B of 22dB, a wind load of 2.8 sqft, and a cost of $869.
>> 
>> EF-510 (10M with 5 elements) has a boom length of 18’, a gain of 15.1dBi, a
>> F/B of 23, a wind load of 2.5 sqft, and a cost of $799.
>> 
>> The total wind load of the 3 monobanders is 10.8 sqft and a total cost of
>> $2,968.
>> 
>> So, at first glance, the price and wind load of the tribander is
>> practically the same as the sum of the 3 monobanders.  There is no more
>> than an additional 0.5dB of gain (and 0.5 dB loss of gain on 10M) with
>> monobanders;  a gain of 2dB F/B (and 2dB more F/B on 10M) for monobanders.
>> 
>> However, I am aware that there will be a degradation of the performance of
>> at least the middle monobander if I put 3 of them, in a Christmas tree
>> fashion, on a 15’ mast.  I haven’t been able to find a good discussion of
>> the amount of degradation—even the 22nd Edition of the Antenna Book has
>> only a few words to say about this.  Please direct me to a discussion of
>> this topic if you know one.  I may have to model these antennas on EZNEC to
>> see the impact of 3 antennas confined to a 15 foot mast.
>> 
>> On the other hand, there has to be a compromise when 3 antennas are mounted
>> on a single boom.
>> 
>> I would really appreciate your help in finding all of the specs I should be
>> looking at in making this decision.  Any other comments that would push me
>> one way or the other would also be appreciated.
>> 
>> Please help me with my first tower!
>> 
>> 73, Wayne KK6BT
>> _______________________________________________
>> 
>> 
>> 
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