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Author Topic: Off Center Fed Dipoles  (Read 707 times)

Offline KC8AON

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Off Center Fed Dipoles
« on: November 20, 2014, 14:01:37 UTC »
I see many descriptions of OCFD on the web mentioning various offsets for the placement of the feed point.  I see them listed being fed 1/4 from one end and, 1/3 of the total length from one end, and even one that says to feed it 19.5% from one end with 80.5% on the long end to gain more bands.

So, with that - what are you fine QRP folks using as your feed point position and why ?

Also, what ratio of balun are you using ?  And are you using a current balun or voltage balun ?

Lets get the antenna juices flowing and discuss some ideas here !

Offline KC8AON

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Re: Off Center Fed Dipoles
« Reply #1 on: November 25, 2014, 13:15:38 UTC »
Not a lot of you folks into building antennas I see.  After 2 topics I've posted on homebrew antennas, got zero replies on them, but I see several posts on things like the Gwhip, unun fed end fed wires, buddy poles, etc which are all store bought antennas.  Doesn't anyone build their own antennas anymore ?

Offline GM0LVI

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Re: Off Center Fed Dipoles
« Reply #2 on: November 25, 2014, 13:59:21 UTC »
Hi Richard.
Regarding homebrew antennas: There have been two postings over the past two days with details of home built antennas and if you look further back you will find several references to home brewed antennas and baluns.
I've built several quads and also phased verticals at the home QTH but my situation at home doesn't lend itself to long lengths of wire and when I'm /P in Scotland I'n usually in coastal locations on the west coast with hardly a tree to be seen! Last winter I made a mag loop for 17m - all from 'junk'.

Don't let lack of responses put you off posting  ;)
Dave

Offline KC8AON

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Re: Off Center Fed Dipoles
« Reply #3 on: November 25, 2014, 16:53:47 UTC »
I opologise for my venting, but I see a potentially good forum here and just hate to see it not being utilized and get some ideas flowing and folks experimenting again.  Amateur radio anymore just seems to be full of companies wishing to make a quick buck by selling compromise antennas at high prices.  Like the other day and it may have been on t his forum I don't recall for sure though.  But I saw one operator that bought a multiband (so called anyway) mobile antenna for $125 and it must be used with a tuner.  Thats a lot of money considering that you still got to buy a tuner to make it work when a $15 Hamstick type antenna and a tuner would do the same for a lot less !  In fact, you could buy a Hamstick type antenna for each band 10 thru 80 meters for around $120 and have a seperate resonant antenna for each band and skip the tuner.  I've personally ran 3 seperate Hamsticks on one magnet mount at the same time and had 3 bands of operation without needing to change anything other than the band selection on the radio.  Anyway, I just want folks to know that their are easy alternatives that can save you money - just don't be affraid to ask for help or ideas before you lay down your hard earned cash !

73, KC8AON