Dear Bob:
I, too consulted ON4UN's book, as there are few other sources that explain this
well. A couple of questions:
1) How tall is your tower and is it a crank up?
2) How did you go about coupling the elements to the boom?
3) Did you add radials? If so, how many?
4) Have you compared your sloper with a dipole at similar heights? I have an
Inv Vee now and it performs ok, though I would like a better DX antenna for the
low bands...
Thanks again.
73,
Ed NI6S
--- On Sun, 12/28/08, Bob Kellow <RSKellow@verizon.net> wrote:
> From: Bob Kellow <RSKellow@verizon.net>
> Subject: Re: [TowerTalk] Quarter Wave Sloper (half sloper)
> To: navydude1962@yahoo.com, towertalk@contesting.com
> Date: Sunday, December 28, 2008, 9:11 AM
> Ed:
> I will share my experience with a 1/4w 80m sloper hanging
> from my tower with
> 3el SteppIR on top.
> The sloper is homemade, about 72 ft long, hanging from the
> tower at about
> the 72 ft level, and making close to a 50 degree angle.
> I modified the SteppIR to ground the elements to the boom,
> which makes it a
> capacity hat.
> The resonant frequency was about 3.8MHz, with the SteppIR
> set for 15m with a
> 2:1 bandwidth of about 100kHz.
> With the SteppIR set to 20m, the resonance was moved to
> 3.6MHz, also with a
> 100 kHz bandwidth. I also found a <2:1 VSWR at 30m.
> After I added the 40/30m dipole to the SteppIR, I could get
> a better match
> at 3.5MHz.
> With the help of a AIM4170 antenna analyzer, I found that I
> could match it
> on 160m with a simple series loading coil I could switch in
> or out using a
> relay. The SteppIR could move the match around on 160m
> also.
> The bottom line is I now have reasonably matched antennas
> for all bands with
> just the SteppIR and the sloper.
> With this configuration I have added substantially to my
> 80m & 160m country
> counts.
> As a side note: Before adding the loading coil, I used a
> SGC remote tuner to
> tune it to 160m.
> Adjusting a sloper can be problematic; I tried lengthening
> it to move the
> resonance lower, but while resonance moved lower, the
> resistance value
> increased, for a net no improvement.
> I agree with you that the sloper is mainly a matching
> device to the tower,
> as ON4UN notes in his book.
> Your mileage may vary, I have the good fortune that the
> tower and antennas
> are in a pasture that has experienced over 100yrs of bovine
> fertilization
> (:^).
> 73s, GL, es Happy New Year.
>
> Bob, W5LT
>
> -----Original Message-----
> From: Edward Sylvester [mailto:navydude1962@yahoo.com]
> Sent: Sunday, December 28, 2008 1:54 AM
> To: TowerTalk@contesting.com
> Subject: [TowerTalk] Quarter Wave Sloper (half sloper)
>
> Been trying to get up to speed on these...Learned that
> height is not
> important, as it's the tower that will radiate,
> primarily. My tower is 70'
> with a Steppir 3 ele and other assorted antennas for VHF,
> all on a 10' mast.
> Looking at the Alpha Delta DX-B, which would give me
> 30/40/80/160m. Has
> anybody installed one of these on a 70' tower? If so,
> what height was
> ideal? Would like to do this right the first
> time....Thanks.
>
> Ed NI6S
>
>
>
>
>
>
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