[MRCA] 60 Meter portable operation questions

[Gene Smar]

Mike:

 

     I’m just getting around to putting in my two cents on this item.  My NVIS antenna system for 60M is an inverted Vee supported by a set of fiberglass cammo support poles about 19 feet tall.  I use the Vee wires as one pair of guys along with a second set of wires, for 80M or 40M, as the other set.  I feed it with RG-8X; it’s almost as small as RG-58 but can handle higher power.  The Vee wires are shorter than dipole wires supported at reasonable heights so don’t be surprised if you have to cut quite a bit off from dipole lengths.

 

 

73 de

Gene Smar  AD3F

P.S.  It was this antenna system that we used at Gilbert a few years ago, as Joe Munson described in his post.

 

 

From: MRCA [mailto:mrca-bounces at mailman.qth.net] On Behalf Of MICHAEL ST ANGELO
Sent: Thursday, January 05, 2017 11:00 AM
To: mrca at mailman.qth.net
Subject: Re: [MRCA] 60 Meter portable operation questions

 

I've enjoyed the discussion on the 60 meter portable antenna. Let me summarize.

 

Al and others recommended an end-fed half-wave resonant antenna. Since Breck had to feed at the base of the mast this is the route he took. 

 

Advantages are you don't require a long transmission line. The disadvantages are you need a counterpoise and you have to watch the losses in a matching circuit matching such a high impedance transformation about 5000 ohms to 50 ohms.

 

Mindful of the losses in a matching network Ray recommended a center-fed half-wave inverted V fed by transmission line. Since the impedance is low a matching network is not needed. I counterpoise in not necessary.

 

Someone else recommended an end-fed 5/8 wavelength antenna. The impedance is lower and is easier to match.

 

My telescoping pole is a fiberglass Jacktite pole which can go up to 30 feet but cannot support a heavy load. Al suggested a lower height is suitable for NVIS. The Jacktite pole is supported by a tripod.

 

I will first try a half-wave center-fed inverted V fed with RG-58 since that is the easiest to build. I will see how my pole supports the load.

 

I'll then try a half-wave end-fed V with a matching network. I will try Breck's matching network or a L or PI network to match the load and put down a couple of counterpoises.

 

I probably will not wait until spring but end up doing this during the coldest weekend of the year. It seems do antenna work in the winter.

 

Mike N2MS

 

 

 

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