[PVRCNC] antenna tuner recommendation for 75/80

Thu Apr 9 20:52:51 EDT 2020

Hi Tad,

If you are limited to just the wires you have up now, then one idea to at least get something out on 80 would be to turn it into a loaded vertical- 25’ tall with the horizontal wires loading it.  It would need extra loading at the bottom of the 25’ section to make it resonant, but maybe you have a way to make that invisible.  Plant some bushes?  And of course, you would want to bury some kind of radials.

Mechanically, you would need to break the feed line at the bottom of the vertical section of coax, and add a way to go straight thru for the dipole or tie the two sides of the vertical coax together into a single element going up.  You might (probably?) also need a way to bypass the balun, which you could do with a very small relay box that connects to the bottom of the balun.

Hopefully this will stir up some more ideas for you.

73,
   Rob K4OV

> On Apr 9, 2020, at 12:33 PM, <tdanley at centurylink.net> <tdanley at centurylink.net> wrote:
> 
> Tony and Don, thank you very much for your feedback and suggestions – it has been years since I used non-resonant antennas, and now I remember why.  I also appreciate the heads up about potential damage to the balun on the existing 40-10 OCF!  Unfortunately additional antennas/feedlines, or modifications to my existing antenna are not an option.  
> 
> 
> 
> MyAntennas rates the 4:1 current balun in my 40-10 OCF @ 3kW ICAS.  I wonder if I can get by running low power or even QRP on 80, and using an antenna tuner like an Ameritron ATR-20/30?
> 
> 
> 
> 73,   
> 
> 
> 
> Tad Danley, K3TD
> 
> 
> 
> From: Anthony Scandurra <k4qe at icloud.com> 
> Sent: Wednesday, April 8, 2020 1:23 PM
> To: tdanley at centurylink.net
> Cc: PVRCNC <pvrcnc at mailman.qth.net>
> Subject: Re: [PVRCNC] antenna tuner recommendation for 75/80
> 
> 
> 
> Tad,
> 
> 
> 
> If you try to use your 40-10 OCFD on 80/75, you will blow up the balun in short order.  You might arc the connector, too.
> 
> 
> 
> There are no good alternatives here.  This is an age-old problem for folks with limited space.
> 
> 
> 
> You can do one of three things as I see it.
> 
> 
> 
> 1) Replace your OCFD with an EFHW for 80-10 like one of these: https://myantennas.com/wp/product/efhw-8010p.  It will require reorienting your layout, but it might provide you with a more easily hidden configuration.
> 
> 
> 
> 2) Replace your 40-10 OCFD with an 80-10 OCFD and shoehorn it into your property as best you can.  It does NOT need to be perfectly straight.  Dog leg the extra length like an L laying on its side and/or let the extra length drop to the ground (protect it from human touch!).  You should try this: http://www.spiderbeam.us/product_info.php?info=p276_Aerial-51%20Model%20807-HD%20%20%20***%20NEW%20***.html  Pay close attention to the RMU units.  You will need two to cover the band segments you desire.  They will need to changed out depending on where in the band you want to operate.  No, it’s not convenient.
> 
> 
> 
> 3) I know you said you didn’t want to add another antenna(s), but I would be remiss in not suggesting that you add heavily loaded dipoles (one for 80 and one for 75 cuz you won’t be able to get one to cover both) into the existing space.  You can get them from http://www.hypowerantenna.com. You can use a tuner to expand their narrow bandwidth but only slightly.  Mount them in parallel with your existing OCFD.  They would each need another coax run.
> 
> 
> 
> Good luck!
> 
> 
> 
> 73, Tony K4QE
> 
> 
> 
> 
> 
> On Apr 8, 2020, at 12:23 PM, tdanley at centurylink.net <mailto:tdanley at centurylink.net>  wrote:
> 
> 
> 
> Hello, PVRC NC - I would appreciate your expert recommendations on the type
> and brand of antenna tuner I should take a look at for my specific use case.
> My home station antenna is very modest for HF - a 40-10 meter OCF at 25'
> hidden in the trees at the back of our lot fed with 85' of DX Engineering
> 400MAX direct burial coaxial feedline.  Also have a Par Omniangle for 50 MHz
> at 30'.  These antennas and feedlines have the unique benefit of being
> completely invisible to all neighbors from any angle!
> 
> 
> 
> Modest results on 40-10 I can live with, but I would like to find a way to
> get the OCF to work on 75/80 so I can chat with a couple friends in the
> evening, and work on my cw skills - running 100 watts with my IC-7610.  I am
> limited to the existing HF antenna and coax as I don't have room for a 3rd
> stealth antenna.  I had considered the attic, but between the radiant
> barrier being a Faraday cage and the noise and RFI mitigation, I want to
> utilize what I already have outside.
> 
> 
> 
> Thank in advance for your feedback, and 73, 
> 
> 
> 
> Tad Danley, K3TD
> 
> 
> 
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