[UK-CONTEST] Building and testing VHF antenna combiners

[Steve Thompson]

52 ohms vs 50 - unless you've paid a fortune for a professional 
grade directional coupler, your VWSR meter won't be able to 
measure the difference and no transmitter will notice or care.

What's the arrangement of your 4m combiner? Depending on how it's 
built you might expect to see 2:1 VSWR or very high VSWR if one 
load is open circuit.

Steve

> Hi All,
> 
> I am planning to make a four way power combiner for 144MHz,
> with the materials I have to hand the Zo will work out to be 52
> ohms, in reality is this close enough to 50ohms to make no
> difference, I do not want to waste any hard earned gain. Would
> it be possible to increase or decrease the length of the 1/4
> wave lines in the combiner to make it look like 50ohms?
> 
> I have built a two way combiner for 70MHz, I wanted to check
> this out so I put a SWR meter on the input and placed loads on
> the two outputs, this gave me a very low SWR, surprisingly I
> disconnected one of the loads and SWR did not rise as much as I
> would have thought, something like 1.5 or 2 to one, I expected 
> 3:1. Is there a better way to test out a combiner.
> 
> Many thanks
> 
> Nick G0HIK