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Author Topic: 75m-40m AM QRO Antenna Recommendation - No Tower  (Read 1203 times)
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K1JOS
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« on: May 30, 2024, 10:31:16 AM »

I am setting up my first dedicated AM station for 75m and 40m.  I have a Viking 500 almost ready to go live and also buying a SuperSenior 80-40.  For SSB/CW I have a 2kW-ICAS EFHW that has worked very well but would not handle the Viking or SuperSenior.  I do have several 80-90' Black Locust trees near the shack but little room for ground radials.  Any advice would be very much appreciated.

Jerry NY2Kw
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KF4NU
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« Reply #1 on: May 30, 2024, 06:12:36 PM »

You already have ready made masts there, how about Inverted V's.

73's
Mickey KF4NU
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w9jsw
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« Reply #2 on: May 30, 2024, 07:39:32 PM »

An 80/40 fan dipole is what I use. Works perfect. I run a pair of 813s modded by a pair of 813s. Handles the juice just fine. Cut for the AM portion of both bands.
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W7TFO
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IN A TRIODE NO ONE CAN HEAR YOUR SCREEN


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« Reply #3 on: May 31, 2024, 01:50:56 AM »

Thinking outside the box, a steerable tuned loop would magnify your ERP a bit...

73DG
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K8DI
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« Reply #4 on: May 31, 2024, 08:52:35 AM »

Iím similar to John on this with an 80-40-20 fan dipole, hung very slightly inverted V style. The ends are 5í down. I run the RCA into it with no issues.  Thatís a kilowatt plus of carrier converted broadcast transmitter, so, yeah, wire antennas can handle the gasÖ

Ed
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Ed, K8DI, warming the air with RF, and working on lighting the shack with thoriated tungsten and mercury vapor...
w9jsw
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« Reply #5 on: May 31, 2024, 09:24:29 PM »

Thinking outside the box, a steerable tuned loop would magnify your ERP a bit...

73DG

Some loop antenna information - https://kk5jy.net/magloop/
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KA7WOC
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« Reply #6 on: June 01, 2024, 05:27:51 PM »

Full wave loop has worked well for me.  I run open wire into a Kilowatt Matchbox.  Held up by trees.
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Bob (aka Boatyard)
WD4DMZ
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« Reply #7 on: June 02, 2024, 03:19:47 PM »

For my AM set-up I use an MFJ 80/40 meter dipole. Total length is under 90 feet as a flat dipole. SWR is great for all of 40. Under 2:1 on 80 for about 100 khz, under 3:1 for over 150 khz.

If MFJ still has any in stock the 800 watt version runs under $100.

Inexpensive and easy to set up.

Rich
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W8EJO
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« Reply #8 on: July 13, 2024, 12:34:47 PM »

This may work for K1JOS with all those tall trees.

80-10 loop.

I recently downloaded the latest (free) version of EZNEC (https://eznec.com/) & have been modeling an 80-10 horizontal loop for my NW Michigan cabin. I have 5 acres & lots of tall trees but no tower. Iíll be heading up soon for an extended stay & wanted a simple multi band wire antenna.

After many tries I finally arrived on an isosceles triangular shaped loop that should cover 80-10 with 50 ohm coax feed (with 4:1 balun @ feed point).   

The loop is 274í in circumference. The base is 80í & each side is 92í.  Height is 40í.
The SWR 200 is below 2:1 on 40, 20, 15, 12 & 10. It is below 3:1 from 3.6 Ė 3.8 and 3.3:1 @ 18.1 MHZ.
A 4:1 balun @ the feedpoint should make modern rigs with internal atuís happy.

Hopefully it actually works as well as EZNEC predicts. Iíll find out next week.








* 80 Hloop plot.pdf (94.8 KB - downloaded 17 times.)
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Terry, W8EJO

Freedom and liberty - extremist ideas since 1776.
w9jsw
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« Reply #9 on: July 13, 2024, 09:59:32 PM »

Does the circle on the plot denote the feedpoint?
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W8EJO
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« Reply #10 on: July 14, 2024, 07:25:17 AM »

Does the circle on the plot denote the feedpoint?

Yes.

I tried to attach the EZNEC file but that file type is prohibited.
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Terry, W8EJO

Freedom and liberty - extremist ideas since 1776.
WD8BIL
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« Reply #11 on: July 15, 2024, 09:27:55 AM »

125' flat top, balanced feedline w/ link coupled transmatch.
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