Hi John
The more I look into this the more I want to try to roll my own so to speak.
I didn't know that the al was used to reduce costs. So I might even end up
with more sensitivity with copper. That a good idea thanks.
I am thinking in terms of the trap covers. Not sure where to go with this. I
think the drink cans might be too flimsy as they are getting thinner and
thinner these days.
Now a small metal Folgers coffee-can might work and Lord knows I drink that
like its going out of style.
Bob AD5VJ
> -----Original Message-----
> From: towertalk-bounces@contesting.com [mailto:towertalk-
> bounces@contesting.com] On Behalf Of John E. Cleeve
> Sent: Wednesday, April 14, 2010 7:41 AM
> To: 'Tower and HF antenna construction topics.'
> Subject: Re: [TowerTalk] Hygain 18AVT trap for 20mtr/40mtr
>
> Hello Bob,
>
> Pity about the missing traps, but I am glad you were able to
> diagnose the problem with the 15m trap. Now you can see how they were
> made,
> it should not be difficult to obtain plastic tube or rod to use as the
> former, with the added aluminium tube to fit at each end.
>
> The outer trap cover forms the fixed capacitance, coupled to the
> coil and the lower antenna element, and the plastic spacer adds some
> mechanical stability; however, it may be possible to re-use aluminium
> drinks
> cans, after you have drunk the contents, to form the basis of your
> replacement HB traps. You will need to work out the inductance and
> capacitance to work on the missing bands, but with some ingenuity, and
> a
> GDO, I am sure you will succeed. You could use copper wire of course;
> the
> aluminium stuff was used by Hygain because it was cheaper!
>
> The last resort might be to seek another 18AVT from Ebay or your
> friends....I have two in my garage, both destined to be used as phased
> verticals at my remote GM site, but both those came from friends who
> had
> upgraded to verticals with WARC capability. The user manual for the
> 18AVT is
> available as a .pdf on the internet.....best of luck with the rebuild,
> sincerely, John G3JVC.
>
>
>
> -----Original Message-----
> From: towertalk-bounces@contesting.com
> [mailto:towertalk-bounces@contesting.com] On Behalf Of Bob AD5VJ
> Sent: 14 April 2010 13:20
> To: 'Tower and HF antenna construction topics.'
> Subject: Re: [TowerTalk] Hygain 18AVT trap for 20mtr/40mtr
>
> Hi John
>
> Excellent post!!
> Thanks very much for sharing this.
>
> I had looked at one of the traps late last night and thought it can't
> be
> that hard to take it apart and examine it.
>
> So I actually did exactly what you described. I took the 15 meter trap
> apart
> and it actually came apart very easily once the screws were taken out
> of the
> one end and you turned the spacer a little.
>
> Just as you said one of the screws holding the inductor wire to the
> tubing
> had rusted and released its hold on the inductor wire.
>
> Looks like about 12 awg wire. Now I am seriously considering making my
> own
> for 20 es 40 meters since they are missing. I could get some 1/2"
> delrin rod
> to wrap onto for the coil and the al wire. A couple of pieces of 1 inch
> al
> tubing and would be 90 percent home free. Now the trap cover might be a
> different story, not sure how to get that.
>
> The only problem is I cant find any al wire more than around 14 awg and
> it
> only comes in 4 foot lengths. Need to find longer spool of wire.
>
> Bob AD5VJ
>
>
> hn E. Cleeve
> > Sent: Wednesday, April 14, 2010 4:37 AM
> > To: 'Tower and HF antenna construction topics.'
> > Cc: 'Tower and HF antenna construction topics.'
> > Subject: Re: [TowerTalk] Hygain 18AVT trap for 20mtr/40mtr
> >
> > Hello Bob,
> > I have used, and still have and 18AVT/WB which has served me well
> > for many years, both in the UK and abroad. However, there have been
> > trap
> > problems, but all off which were repairable.
> >
> > To get to the inside of the trap assembly, you undo the self
> > tapping
> > screw which fixes the outer cover of the trap to the antenna element
> > assembly, then you rotate the inner plastic spacer at the bottom of
> the
> > trap, until you can slide the entire cover etc. down and away from
> its
> > original position.
> >
> > This will expose the inductor, and at each end of the inductor
> > you
> > will find a self tapping screw which connects the inductor wire, at
> > each end
> > to the antenna element. In my example this self tapping screw
> > originally was
> > not made of stainless steel, and it did not have a washer beneath the
> > head
> > of the screw, and so, on assembly the screw head "bit" into the
> > aluminium of
> > the inductor wire, and eventually the rust from the screw and the
> > stress on
> > the inductor wire, which caused the inductor wire to fracture at the
> > screw
> > head/wire contact, that caused the problems I experienced. There is a
> > similar situation at each end of the 80m top loading inductor too.
> >
> > So, I suggest you obtain some new stainless steel self tap
> > screws,
> > plus washers. Obtain some aluminium wire of the right diameter, and
> > simply
> > rewind the inductors, only a few turns each, in grooved formers,
> > carefully
> > tighten the new self tap screws and then coat the junction of the
> > screw/washer/inductor wire with a non hardening insulation, and then
> > reassemble the outer covering, and you should be back in business.
> >
> > Sincerely, John. G3JVC.
> >
> >
> >
> >
> > -----Original Message-----
> > From: towertalk-bounces@contesting.com
> > [mailto:towertalk-bounces@contesting.com] On Behalf Of Bob AD5VJ
> > Sent: 14 April 2010 03:08
> > To: towertalk@contesting.com
> > Subject: [TowerTalk] Hygain 18AVT trap for 20mtr/40mtr
> >
> > I was given an old Hygain 18avt vertical and had plans on mounting it
> > atop
> > my tower since it is low profile and does well in the wind. But I
> just
> > went
> > to Hygain's website and it appears they don't stock parts for it.
> >
> > I am needing the 20 meter and 40 meter traps anyone have any idea
> where
> > I
> > can find them - Google did not find anything, unless I didn't put in
> > the
> > right words -- I just Googled "Hygain assy (and then the 870 number
> in
> > the
> > manual).
> >
> > 73,
> > Bob AD5VJ
> >
> >
> > _______________________________________________
> >
> >
> >
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