Yes, I know the Bird 43 well. Years ago I worked as a shipping clerk in a ham radio store and I remember that we sold them as well as the fact that we had one on our test bench. I now regret not getting one back then when I had my employee discount. As it was, I was like the proverbial "kid in a candy store" and was lucky to get home with my paychecks intact.... hi hi Michael ----- Original Message ----- From: "i8cvs" domenico.i8cvs@tin.it To: "AMSAT-BB" amsat-bb@amsat.org; "Michael Tondee" mat_62@netcommander.com Sent: Friday, June 06, 2008 11:48 PM Subject: Re: [amsat-bb] 70cm antenna SWR problem solved?
Hi Michael, W4HIJ
For the velocity factor use the value given by the manufacturers for each type of coax cable.
As an example a Vf= 0.66 is OK for the RG 213 and RG-58
Don't make long run of coax without the braid in the vicinnity of the feed point because the inner conductor of the coax cable will add to the lenght of the dipole.
When you measure the SWR slide the palm of your hand over the jacket of the coax cable and if the SWR changes it means that part of the RF current is flowing over the external braid of the coax cable and so you need a balun.
To measure the incident and reflected power to compute the SWR try to buy a BIRD 43 wich is a professional instrument and buy time to time the measuring elements to satisfy your needs.
In a couple of years you will get the most practical and versatile instrument for RF measurements in the shack and over the tower.
Have fun
73" de
i8CVS Domenico
----- Original Message ----- From: "Michael Tondee" mat_62@netcommander.com To: "i8cvs" domenico.i8cvs@tin.it; "amsat-bb" amsat-bb@amsat.org Sent: Friday, June 06, 2008 9:47 PM Subject: Re: [amsat-bb] 70cm antenna SWR problem solved?
Thank you Domenico, I've actually studied all those links before. I would build a CP antenna
as
Howard, G6LVB has done except that I have nothing with which to measure
the
velocity factor of the cable in the phasing harness. When it was working the 70cm linearly polarized did a pretty good job though. At least with
the
LEO's. Unfortunately I have no experience with HEO's. 73, Michael, W4HIJ