Ham Radio Deals https://hamradiodeals.co.uk/forums/ |
|
9:1, EFRW Questions https://hamradiodeals.co.uk/forums/viewtopic.php?f=43&t=140426 |
Page 1 of 1 |
Author: | MI0PYN [ Thu Jan 09, 2025 12:34 pm ] |
Post subject: | 9:1, EFRW Questions |
I'm sorry if these questions are stupid, but there seem to be so many conflicting bits of information around, I'd solicit yet another one :-) I live in a semi detached house, with a 4 band HyEndFed EFHW with 49:1 mounted on my chimney. It's fed from my shack using some decent M&P coax. I am assuming that the coax acts as the counterpoise/ground to some extent as there is no separate connection for a CP at the antenna end, but I've not had any real RFI issues (that I'm aware of) other than a capacitive touch lamp which misbehaves when the radio is on TX. I am considering whether to replace this with an EFRW, primarily to get some other bands which I don't have access to currently. If I were to use a 9:1 and a wire 45ish metres long, I believe I should be able to get a match (with a tuner) on most bands, certainly all that I'm interested in from 80m up. The wire would make at least 2 nearly 90 degree angles, but there would be 15m or so between each of the corners. My questions are these:
Thanks in advance for your collective wisdom. 73, Stefan MI0PYN |
Author: | Mm0rmr [ Thu Jan 09, 2025 4:59 pm ] |
Post subject: | Re: 9:1, EFRW Questions |
You dont need a counterpoise with a 49-1 as there is very little current at the feedpoint and a high voltage and your coax will suffice. If i were you i would stick with the 49-1 and put a longer wire on that around 40m in length to start and shorten it and tune it on 3.550 for optimum swr as that will out perform any antenna with a 9-1. Antennas with a 9-1 are ok if your struggling for space etc and they receive ok but on tx any resonant antenna will work far better. |
Author: | mm0hgn [ Sun Jan 12, 2025 11:02 pm ] |
Post subject: | Re: 9:1, EFRW Questions |
Hi i use a 9.1 unun with 53 ft of wire my ts 2000 auto tuner tunes from 80m to 10m no problem |
Author: | Sangoma [ Mon Jan 13, 2025 7:52 am ] |
Post subject: | Re: 9:1, EFRW Questions |
an IL with the FP just above GL is very effective, and yes use the coax as an adjustable CP, thought sometimes a VSCP at the FP helps. |
Author: | gm0gtu [ Thu Jan 23, 2025 12:33 pm ] |
Post subject: | Re: 9:1, EFRW Questions |
I have an end-fed wire here in Tenerife, 32.6M long, 9:1 UNUN, running horizontally with the last 5M vertical. I have attached a single counterpoise at the UNUN, and I also have around a 9" string of ferrite beads on the coax. 10ft away from the feed point. I've had no problems with RF feedback. Just be aware that there are good & bad lengths of "random wire" I have a table of good lengths that I can send to you if you wish. |
Page 1 of 1 | All times are UTC |
Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group http://www.phpbb.com/ |