locked Need Antenna help to prep for JOTA


David McGuire
 

BLUF: anyone available to teach me how to repair/build portable antenna?

I have not used my Cushcraft R7 in over 10 years.  Does it still work?  No idea.  My current apartment will not permit use of an antenna.  I'm thinking of taking my equipment to Canyon Lake for a weekend of ops. 

I found a nice YouTube video that gives a description of a QRP Field Day antenna, but want to know if this design can be modified for 100w use.  If this design (see attachment) can be modified for 100w use it would be much easier to use for portable ops.

The YouTube video is https://www.youtube.com/watch?v=yH0zKNNGa0s.  Thanks to Kevin KB9RLW!
 
Ideas?

TNX & 73 de David AE4LH


Harold Fleischer
 

A couple of thoughts.

Re R7: SARC has set up an R7 at Field Day on a mast with three ropes as guides staked out on the ground. As to whether your R7 works, an antenna analyzer or vector network analyzer could be used once you have it set up.

Re 15’ antenna. The wire part appears to be pretty standard so it will probably handle 100w. The feed cable looks light, but data exists for most cable if you look up the markings on it. The specified 9:1 Balun should have a power rating if it is commercial. If home brew, the designer should have disclosed the target power rating.

I have a buddipole. The antenna is rated by the manufacturer as 200w. I am using coax rated for over 200w. My limitation is the balun rated for 100w. I don’t have an amplifier so my buddipole variants are good to go with my 100w radios.

Best wishes.

73

Harold AE5AS


Harold C. Fleischer, III
haroldcf@...
210-497-2532


On Saturday, July 24, 2021, 09:12:49 AM CDT, David McGuire <leviticus25_9@...> wrote:


BLUF: anyone available to teach me how to repair/build portable antenna?

I have not used my Cushcraft R7 in over 10 years.  Does it still work?  No idea.  My current apartment will not permit use of an antenna.  I'm thinking of taking my equipment to Canyon Lake for a weekend of ops. 

I found a nice YouTube video that gives a description of a QRP Field Day antenna, but want to know if this design can be modified for 100w use.  If this design (see attachment) can be modified for 100w use it would be much easier to use for portable ops.

The YouTube video is https://www.youtube.com/watch?v=yH0zKNNGa0s.  Thanks to Kevin KB9RLW!
 
Ideas?

TNX & 73 de David AE4LH


David McGuire
 

Thank you Harold for the comments.  I found a couple of 9:1 baluns with one being good for QRP and other other being for 100w.  Both were sold out.  I wrote to the maker to ask if he had a timeframe for new units.

vy 73 de David AE4LH