I want several bands from it so I used to have automatic antenna tuner there
- SGC-237.
It tuned 160...20 just fine and results on 20 was not too much different
from shortened yagi.
The thing is - I wanted to use it with amplifier, so I decided that I gonna
play with the length of antenna to get convenient impedance for simple
matching like capacitor on 80 and coils on 160 and 40...
That's where the fun started - antenna behaves differently from MMANA model
which has very optimistic 8 ohm of ground losses :)
Most likely my losses are due to the soil. It is not even a soil - it is
cliff side of Hudson river and I have clay and rocks under my house.
I have spent a week already cutting the length and measuring during the day
and trying the antenna at night.
All of that is done using Victor VA2WDQ as reference point - he has the same
tower and the same antenna at his house in Montreal.
In short words : "Do you hear him? - NO" or "Did he answer? - NO"
Speaking of distance - don't forget that I live in NYC and working EU from
here might be easier than working east coast from California.
On Thu, Sep 22, 2011 at 5:24 PM, Jim Brown <jim@audiosystemsgroup.com>wrote:
> On 9/22/2011 1:31 PM, Alex Malyava wrote:
> > I need an advice for low band antenna (80-40) which does not need good
> > grounding system.
>
> You are paying far too much attention to impedance measurements. First,
> you should be using an antenna tuner to match the antenna to the rig.
> Second, you are expecting far too much from 100W on 80M. 559 is a great
> report for a path on the order of 3,000-4,000 miles on 80M, especially
> this time of year. I worked the NA Sprint last weekend, and was just
> barely making 75M contacts to GA and New England with 1kW on both ends
> and my dipole at 110 ft from my QTH in CA. That's a 2,500 mile path. We
> made contacts ONLY because there were very good operators on both ends.
>
> As to your antenna -- if you want to use it only on 80/75M, try for a
> length of about 65 ft, and try to make the radials about 25% shorter
> than that. If you also want to use it on 160M, try to make it about
> 90-100 ft, and make the radials as long as you can. You WILL need an
> antenna tuner, but if your rig has one built in, it will probably load
> it just fine.
>
> 73, Jim K9YC
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