Hello Kelley and the group,
Having owned one of these in all of their variant and currently
owning a well used and rebuilt 7BTV (6BTV with 17 meter add on kit) I have a
few suggestions.
Make up a length of coax that is ELECTRICLLY a half wave at 3.55 Mhz
and use it as your feedline. Preferably something larger in size like RG8 or
RG213, 9913, etc. You can use your MFJ to cut it to length.
This gives you half wave multiples for each band except 15 meters.
IF the feedline is not underground except for the small length near
the antenna then you will need to make up some solenoid chokes to keep the
RF off the line. 8 to 10 turns around a large soda bottle works ok and is
cheep for testing, wrap with duct tape to hold it on. I did this for 6 years
in the sun and it worked fine. The first one should be near the feed point
and another just outside the ends of the radials IF they are above ground.
If not, just at the feed point is good.
This will take the feedline out of the equation and give you a
reasonably accurate measurement of the antenna at the end of the coax.
I tend to agree with the fellow that suggested that the 20 meter
trap might be a problem. IF your measurements (physical) between the end of
the tubing and the end of the trap cover are all following the same ratios
for each trap (in spec) and adjusting the trap outer metal housing doesn't
bring the adjustments in line then the 20 meter trap may be either installed
upside down (switched end for end, but unlikely as it would look weird and
be pretty obvious) or there is poor to open contact between the outer metal
shell of the trap and the lower tube (corrosion, coatings, etc). The trap
may have been incorrectly assembled at the factory and is not a 20 meter
trap but had been marked as one. (Rare, bit no one is perfect.)
The full length of the antenna (not including the top loading coil
for 75/80 meters) is the length for 40 meters so the 20M trap issue must be
fixed first.
I am assuming you do have the 6 metal spikes/top hat in place
because you said it was a 5BTV.
Leave the 75/80Meter coil and whip OFF the antenna while doing these
tests as it only makes the antenna top heavy while raising and lowering it
for adjustments and when you get everything working up to 40 meters, then
you can install the top coil and tune it for its band. It will have almost
no effect on the 40 meter tuning. Perhaps a bit of a shift down in F for 40
which you can adjust for in the end.
Too bad you are so far away as I would be glad to give you a hand
with it but the drive from Phoenix might be a bit prohibitive. ;>)
Keep us/me posted with your results.
Push comes to shove, you might have to ship the trap back to Hustler
and have them evaluate or replace it.
IF you happen to have a buddy in town who has a spare 20Meter trap
you could borrow, you could just swap it out and see if it tunes up then.
Good luck.
When they are working, the work quite well.
200+ countries worked the first year I had it installed here at this
QTH, 40M in the mornings, 20M daylight hrs, CW ONLY, 135W Output from an old
C-Line and I worked swing shift M/F. so, the DO work.
Let me know if I can be of any further help.
Michael Baker K7DD
k7dd@cox.net
-----Original Message-----
From: towertalk-bounces@contesting.com
[mailto:towertalk-bounces@contesting.com] On Behalf Of Kelley
Sent: Wednesday, January 20, 2010 6:55 PM
To: Tower and HF antenna construction topics.
Subject: Re: [TowerTalk] Hustler 5BTV Problem
I can certainly add 10 feet to the coax, but, as I should have mentioned
up front, the SWR measurements were taken using an MFJ analyzer
connected to the antenna with about 6 feet of coax.
Kelley - W0RK
On 1/20/2010 7:07 PM, Mike Murphy wrote:
> Just a guess, but your 60 feet of coax is suspect here. Try adding 5 or
10 feet of coax and I bet your problems go away.
>
> Good Luck!
>
> __________________________
>
>
> Michael Murphy - KD8OK
>
>
> kd8ok@yahoo.com
> __________________________
>
>
>
>
> ________________________________
> From: Kelley<kshaddrick@jetup.net>
> To: towertalk@contesting.com
> Sent: Wed, January 20, 2010 6:47:32 PM
> Subject: [TowerTalk] Hustler 5BTV Problem
>
> I've been working with a 5BTV antenna for about two weeks now. I've got
> good SWR readings on 10m, 15m and 80m. Higher but usable readings on
> 20m. However, I can't get anything under 2.0:1 on 40m. The antenna is
> ground mounted with 20 25' radials. It's fed with about 60' of coax.
>
> I've tried the normal tuning as well as adjusting the traps. Nothing
> seems to bring the SWR on 40m down to something usable.
>
> Anyone have any ideas I can try?
>
> Kelley - W0RK
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