G7FEK Restricted Space an 47199....
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Posted By Sean - G3ESE on 17 Jul 2026
“To answer Howard's question, the feeder is 450 Ohm 'window' line, which can be purchased easily. I am contemplating making some 600 Ohm ladder line, SOTABeams sell the spacers and a terminator or the correct dimensions to give 600 Ohms, when coulped with multistrand insulated wire. I did a calculation based on current (July 2026) UK prices and to make the 7.5m length of ladder line, plus enough spaces, the termination and enough wire to carry on the ladder line so the entire top can be made from the same piece of wire on each side (they sell 50/100m of heavy duty green antenna wire) would cost £34, plus P/P If you buy the 100m of wire, you should have enough to make the ladder line, antenna, and counterpoises for around £55 (about $70 US or so). My version of the antenna, at the moment, has 450 ohm window line, the 'standard' top lengths and two extra vertical sections, one for 30m and one for 20m. I have added 6 extra counterpoises, one for each band) but thety are not accurately tuned - I cut to the standard 1/4 wave lengths as shown on various sites. I have not tuned the top lengths either, just followed the given dimensions (well as accurately as I could cut them, so they maybe a bit different from the published ones). The antenna tunes (with the internal atu in my FTdx10) on all bands from 80-6 (it works really well on 6m for some reason) except for 60m, where it is a really bad match (as you would expect). However despite the crazy high SWR, my external ATU can get that down, so I can still use the band. I can even get a match, of sorts' on 160. Testing on 30m shows my signal being heard all over the world, even in ZL7 (19000km from here). Last night I worked HS and in the morning VK7. Similar situation on 17m. I've worked a few on 6m, but RX on 6 is superb, Several US stations including 6 and 7 area, D2; BY; JA; UN; UA9; EX, etc. For a small antenna it has a BIG voice! I'll get to properly test it on 80m when the days are shorter, but so far I am impressed. For a compromise antenna, it will take some beating - I am sure it's the best all-band antenna I have used in nearly 45 years on HF. 73 de G3ESE (ex G4UCJ) ”
Posted By Howard Doss on 17 Mar 2023
“What is the impedance of the twin feed, was it a home brew, if so what are the specs. Howard N5WIO”
Posted By Mike, G7FEK on 1 Jun 2010
“Hi Peter,
I am in the process of moving house so I cannot test and publish a 10m modification right now.
Take a look at Juko's 30m mod, shown in the current pdf document on my website.
It is similar to the mod required for 30m, but for 10m make the shorted stub only appx 2.5 meters along from the vertical section, not 5.5meters as Juko says. This will make a tuned stub for 28MHz instead of 10MHz. This is quite complicated to get exactly right and you will need an analyser to find the exact length needed but it should be about 2.2 to 2.5m in length and open at the end near to the vertical feeder just like the picture. You need to use 450 ohm twin to make the stub.
I hope this helps.
All the best,
Mike, G7FEK.”
Posted By M6PAV - Peter on 1 Jun 2010
“hi mike i built this antenna and was totally amazed at how it works. Ive had many a contact into the north states and canada in the past 2 weeks, and all on 80mts. i was woondering if you had the 10 metre`s mod available? if so could you send it to my private e-mail please..
many thanks
Peter M6PAV”
Posted By Mike G7FEK. on 23 Jul 2009
“David, I use a 9m fibreglass fishing pole with the top section removed. For this test we used a 7m pole inserted into a metal pole at the base giving an extra 50cm of height.”
Posted By David M6WOW on 20 Jun 2009
“Do you use a Spider beam pole, Mike?
I put my version up on my SOTABeam pole when I first built it but it wasn't tall enough. I'm buying a FT101ZD so will need to use it with your antenna at chimney height and partnered with a 12 metre pole. I shall build the VK5JST analyser kit first. M0XLE and I haven't managed to get the antenna tuned correctly yet due to no analyser to hand. I'll get there. ”
Posted By Mike G7FEK on 14 Apr 2009
“Andre, let me know how you get on with your build. My antenna is down at the moment due to a fractured pole.”
Posted By Andre, 2E0SKI on 30 Mar 2009
“I was thinking about adding a choke to the coax feed-line somewhere. Now I have the answer! Funnily, I was also wondering if the coax would function like a counterpoise :-)”
Posted By Mike G7FEK on 15 Mar 2009
“I should add that a simple choke made from winding 22ft of the RG58 coax on a 4 inch PVC drainpipe was added near the radio end and about 50ft down the coax from the antenna. When using this antenna with such a simple counterpoise, this choke is essential to ensure that the RF return path is via the counterpoise and not via the radio!. Placing it about 50ft down the coax near the radio end allows the coax itself to contribute to the grounding effect by working like an additional counterpoise. This addition has also proved very effective with my own installation at home.”