[SJDXA] 160 Vertical Advice

Tue Oct 13 09:45:11 EDT 2020

Perfect!!

Thank You both of you for guiding me to what I thought and expected.

KWR

On Mon, Oct 12, 2020 at 11:40 PM Bob Beyer <bob_beyer at verizon.net> wrote:

> Hi Steve,
>
>
>
> It’s a nice looking SWR curve but it doesn’t necessarily tell the whole
> story for a vertical.  Things may change as you add more radials; hopefully
> a lot more.  The good news is that the antenna is at least resonant inside
> the 160m band.
>
>
>
> Recently, an FRC member was asking about verticals and radials for a
> long-term project he has.  Bruce, WA3RHW was asking about how many radials,
> how long, and using various kinds of excess wire he has.  Drew, K3PA
> responded with some info but I thought you might want to take particular
> note of his last point which I’ve highlighted in yellow below.
>
>
>
> This is counterintuitive and can make you think you are doing the wrong
> thing as you add more radials and you see your SWR curve go up.  I believe
> the reason the SWR increases is because radiation resistance increases also
> as the losses decrease and that is a good thing for a vertical.
>
>
>
> Depending on what portion of the 160m band you intend to use, you may want
> to lower the resonant point.
>
> All CW contacts on 160m are made below 1900 KHz with the majority being
> 1870 and lower.
>
> Even in the SSB contests, the distribution still favors the lower portion
> of the band.
>
> On the other hand, if you have a group you like to talk with around the
> middle of the band, then 1885 where you have it now will work fine.
>
>
>
> Typically antennas are evaluated for their 2:1 SWR bandwidth.  I believe
> this is because this is the point where most rigs will begin to limit the
> Tx power (or even sooner).  This antenna looks like it has a 2:1 BW of
> about 43 KHz from 1865 to 1908.
>
>
>
> If I were optimizing it for contest usage, I’d shoot for about 1830 to
> 1835 as the center point.  This would put your 2:1 BW from 1810 to about
> 1853.  DX can’t operate lower than 1810 so I give little concern to the
> very bottom of the band.
>
>
>
>
>
> 73 & GL,
>
> Bob – KE2D
>
>
>
> P.S.  I love getting plots like this from the Rig Expert analyzer and
> software.
>
>
>
> K3PA’s email:
>
>
>
> *From:* GoFRC at groups.io [mailto:GoFRC at groups.io] *On Behalf Of *Drew
> Vonada-Smith K3PA
> *Sent:* Wednesday, October 07, 2020 8:34 PM
> *To:* GoFRC at groups.io
> *Subject:* Re: [GoFRC] Radials
>
>
>
> Hi Bruce,
>
> 1.  On ground radials are not tuned.  There is no advantage to shortening
> them.  Max 'em all out.
> 2.  True, depends on the quality of your soil and lots of other things.
> More is always better.  If you are staying on a budget, start with 20 or 30.
> 3.  Copper wire is best for low loss.  Use what you have. Telephone quad
> should be fine.  The MIL field wire is OK if it is copper outside and not
> just steel.  Just tie the strands together.  Fence wire is usually
> galvanized steel or aluminum.  Galv steel is too lossy and alum corrodes
> quickly in many soils.  I'd avoid the fence wire.
>
> You are right that the insulation does not matter.  The gauge does, a
> little.  I'd go for 18 or 16 AWG as a minimum.  Mechanical fragility is an
> issue as well.
>
> There are ways to determine lossiness of the final product to determine
> how close to perfect your radials are.  With more info on what the vertical
> is, I can give more detail.  You need an antenna analyzer to determine the
> value of R when X=0
> *..  It is VERY important to note...if SWR goes up as you add radials THAT
> IS NOT A BAD THING.  It usually means losses are decreasing. *
> 73,
> Drew K3PA
>
>
>
>
>
> *From:* sjdxa-bounces at mailman.qth.net [mailto:
> sjdxa-bounces at mailman.qth.net] *On Behalf Of *Steve Molo (KI4KWR)
> *Sent:* Monday, October 12, 2020 9:41 PM
> *To:* sjdxa at mailman.qth.net
> *Subject:* [SJDXA] 160 Vertical Advice
>
>
>
> All, hope somebody can give me some ideas….
>
>
>
> Cushcraft MA160V middle of yard / 3 radials so far at 50ft each 120
> degrees separation. Will be adding more but does this look good? Moving the
> stinger we get go anywhere and have 40khz 1:1 or close to that.
>
>
>
> Steve
>
> KI4KWR
>
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