[VHFcontesting] VHF-UHF-COAX CHART

[kc9cuk]

            I am asked by new and old hams all the time, about coax, loss
and how it affects transmit and receive and why I use low loss coax. This is
a simple chart I made to help better illustrate the Importance of using low
loss coax for the 2m and 70cm band. I am offering this chart for everyone to
use and give out to new hams or to help enforce the importance of using high
quality coax for 2m and 70cm operations. I made the chart to illustrate the
loss of watts because a lot of new hams and old do not understand DB DBI DBD
DBM and I thought this will give them a better idea of what they are
loosing.  An example of this is a ham (General Cass) told me that he is
using a 0db antenna at 40 feet with 150ft of rg8x to his TH-F6A HT, this is
the setup he got for 2m and 70cm (the locals hams told him this would work
great). This ham recently updated to a general class to go to HF because he
can't find any activity on 2m, when I explained to him that he was losing
6+db in his coax alone if not more because I'm sure he doesn't have a 1:1
SWR (I don't) plus no gain antenna and connector loss exc. He stated that
wasn't a lot and the setup was working great for him.  I told him I was
getting about 1 S UNIT on him and that if he put up lmr400 low loss coax
alone he would be able to talk to me with low power and should see a good
increase in his receive signal to, I also told him I don't like to run more
than 50-70ft runs of lmr-400 because of the loss and he should move his
station closer to the tower if possible or the antenna closer to his
station. This amazed him and he asked how that was possible and I explained
to him the db loss in coax and he still didn't get it, then I stated the
5watts he was using on high turned out to be around 1 watt at the end of the
feed line due to loss. All of the sudden a light came on and he got it and
this was the inspiration for me to make this chart. I would like to see more
new hams use 2m and 70cm but with poorly setup stations they get discouraged
fast and usually drop out of the hobby (this is bad). With the money this
guy spent on the wrong gear he could have put up a respectable 2m station
and really enjoyed it. Sorry for the long email just thought it was a good
example.

 

LINK TO CHART   

 

http://www.hamgeeks.com/uhfvhfloss.htm

 

 

73 

KC9CUK

 

PS I am far from a expert and don't know everything but I'm trying to LOL