[K3PZN-List] bozooka antenna verse diapole antenna

[Andy Leeds]

I have bazookas on 80 and 40. Curt is correct, my logic was to cover as 
much of 3.6-4.0 under 2:1 as I could since my amp doesn't like high SWR 
especially in its auto-tune mode and I wanted to avoid purchasing an 
external tuner. Auto-tuners for full power are rather expensive and 
while a manual tuner can be had for under $400 going that way I would 
add a manual function back into the station where I'd worked to 
eliminate the need to tune as I move frequency. On 40M I ended up with a 
bazooka vs dipole just because I was already buying one bazooka for 80 
so I ordered the 40M one at the same time.  Its also a holdover from my 
time in FL near the beach - the coax jacket of the bazooka held up well 
in the salt environment, bare wire didn't fare so well.

Drawbacks are the weight, looking at it you can see that it sags or 
curves more than a dipole, and there is a good bit more strain on the 
ropes holding it. Both of mine have survived the recent storms with no 
issues. I think a good ice storm will kill the 80M one breaking it 
someplace.

Recently the SWR on the 40M one went wacky on me, one of the storms had 
re-aligned it some. I just dropped it to the ground then pulled it back 
up in place working the ends a bit to get it into the right position and 
everything settled back down.  The 80M one is also a bit off right now 
since I moved one of the ends so we could do some work on the garage 
roof. Once there is decent weather I'll get a line over a tree nearby 
and move that end out where it needs to be.

I have a strong preference for feeding with coax and not open line. I've 
seen too many instances of open line radiating and putting RF in places 
it doesn't belong. If i did use it I'd do so with a remote tuner mounted 
outside to a good ground and still bring coax inside the shack so that 
any line radiation is still outside.

Andy


On 7/5/2012 17:59, Curt Milton wrote:
> Ray
>
> I presume you might be asking about 80m?
>
>
> For 40m, a dipole generally covers the whole band.  Note the percentage:  300/7000 = 4.3%
>
> In contrast for 80m its 500/4000 = 12.5% -- as a result a dipole using has a 'match' over a smaller part of the band.  Hence the interest in the Bazooka antenna.
>
>
> I confess to not having a coax fed dipole for 80m, but in this modern age I suspect a dipole with decent coax and a decent tuner in shack should work fine - particularly in this age of auto tuners.  If the dipole has its resonance near the middle of the band, it might be ok.
>
>
> I can't remember if one of your wire antennas is ladder line fed?  If so the bazooka has no advantage over it - because ladder line is even lower loss than coax.
>
> On the higher bands - greatly mismatched coax has a more dramatic effect -- the multiple bounces combined with higher coax loss equal greatly reduced power.  As a principle, coax is best used with matched antennas - but on 80 and 160m one can get away with some mismatch.  Usually the first problem down there is RF into the microphone.
>
>
> I sense bazooka antennas were much more popular before auto tuners - to minimize labor in operating a station on 80m.  They tend to be expensive and heavy as they are made of coax - so I suggest sticking with a dipole.
>
>
> I wonder what others think on this?
>
> Curt
>
>