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Re: Topband: N5J Live Stream?

To: topband@contesting.com
Subject: Re: Topband: N5J Live Stream?
From: Michael Tope <W4EF@dellroy.com>
Date: Sat, 10 Aug 2024 16:21:23 -0700
List-post: <mailto:topband@contesting.com>
Hi George,

Is this noise you are hearing impulse noise from the generator ignition or switching hash from the inverter electronics?

If it is ignition noise, shielding the spark plug wire fixed the problem for me:
http://www.dellroy.com/W4EF's-Ham-Radio-Page/EU2000i/Ignition.htm

For inverter hash, a #31 toroid in series with the AC output works (trifilar wound with THHN house wire). The idea was to keep the extension cord from becoming an antenna or conducting noise current back to the rig chassis and then along the coax to the antenna feed. I didn't even need to bother grounding the generator, but in my case it was located a fair distance from the antenna: http://www.dellroy.com/W4EF's-Ham-Radio-Page/CQ160/2006.htm (scroll down to the photo of the generators and gas cans). The filter in the Cantex box is mostly for higher bands (uses #43 toroids), but I believe the unhoused toroid with the green THHN on it is a #31 type.

If you need one at the antenna, 6 to 8 eight short radials 30 to 60 feet long would probably make a decent counterpoise to provide a low impedance to shunt against the series Z of a common-mode choke you are putting on your antenna coax. I built one of those W8JI receiving 4 squares many years ago and I used eight 60ft long radials for each vertical. That seemed to work very well (IIRC that is what Tom recommended and I just followed his recipe). Critters chewed the guy ropes and the vertical all fell down, but that's another story :-)

Hope that helps.

73, Mike W4EF...........

On 8/10/2024 12:00 PM, GEORGE WALLNER wrote:
Jim,
We are using all of the cores you have given me. They help, but it is hard to get a good ground at the top-end of the beach where the sand is very dry and rocks prevent rods getting driven deep enough to reach moist ground. Yesterday, a bit desperate, ran a 70 foot long GND wire to water, but I doubt it is doing much good. We got chokes on most coax and control cables but without good GND their effect is limited.

Using a single #31 2" core, how many turns of RG-6 do you think will give decent choking effect? (I know, it depends on the GND and other loading factors.)
TKS for all the ferrite cores! Will let you know if we need more!

GW



On Sat, 10 Aug 2024 11:48:34 -0700 Jim Brown  wrote:
Hi George,

Remind me where to send you more cores for your next trip. :)

In the meantime, try grounding the generator chassis (and/or grounding pin) to a driven rod (or to screen/radials if you can't drive a rod). I've seen reports that this can be effective with some generators on some bands.

73, Jim K9YC


Set up a DHDL RX antenna yesterday but it was picking up generator noise. Will move it today to reduce noise.



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