[600MRG] Vertical and loading questions.

[Kenneth G. Gordon]

On 12 Jan 2018 at 9:08, Dick Bingham wrote:

> Good morning Ken

Good morning, Dick.

For some reason, I am not receiving anything from the forum directly, so I thank you for 
sending a reply to me off-list. I have contacted the support crew for the forum to see if there 
is something wrong on that end, but so far have received nothing even from them. I think 
Frontier is at fault.
 
> Last week I was doing some EZNEC-5 based calculations of an
> Ell-antenna (28-ft vert plus 72-ft horizon) for 160-meters. I had
> 6-each 33-foot long radials in the model and used a base-located
> inductor. things got better when I added longer radials.

I am using MMANA-GAL, but the results are almost identical. 
> 
> What I found was the radials, as modeled, were too short which made
> for "twitchy" results like your needing retuning every 500Hz.

I had thought of that, but I cannot add length to my radials here. My lot is simply too small.
 
> 
> As a result, I suggest you increase the length of a few radials and
> see what happens. Another caution you need to watch if using a
> hand-held impedance meter like the AA-170 product is do not trust the
> results IF there are nearby commercial BC-band stations. 

No. I don't have one of those. I was simply relying on the SWR bridge in the station here.

> 
> I wasted a half-day trying to match the above described antenna using
> the AA-170. My use of this device at a remote location allowed me to
> erect and tune-up a 630-meter Tee in about an hour. This resulted in
> my innocent trust in the AA-170 when used in the big-city environment
> of my snowbird home. DISASTER. I could tune the antenna for VSWR of
> 1:1 as measured at the antenna base using the AA-170 and finding VSWR
> at the rig at the end of the interconnecting coax greater than 10:1 

Wow! That is quite a difference!

> 
> To a large degree, work closely with an EZNEC prediction for your
> antenna if close by BC-band signals are present.

I do have a BC station nearby. One is within about 6 blocks of my home and they are 
operating on 1450 kHz.
 
> 
> Good luck and let me know your solution to the present problem .

Thank you, Dick. I'll keep the forum informed. As I said earlier, I am somewhat confused 
concerning what, exactly, is the mechanism by which this is working.

vy 73 for now, and thanks again.

Ken W7EKB

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