[Moon-net] Power Divider losses..?

[Leif Asbrink]

On Fri, 11 Jul 2008 13:26:34 -0600
"Jordan" <outposter30 at shaw.ca> wrote:

> If I am using 1" Square AL tubing and a brass tubing with the proper D/d 
> dimensions, how much loss is acceptable per port in a 2m 2 port divider?
> Connectors are Amphenol silvered Ns, the brass is properly centered and 
> soldered, and the dimensions are to design.
> 
> Is .1 or .2dB/port acceptable...?  ie.:
> Fed with -20dBm @ 144.1 , I see -23.2 dBm at each port when the opposing 
> port is terminated with a 50 ohm load.

What you see is (hopefully) mismatch only. It will not affect 
your station performance at all. On the RX side a small (VERY small
in this case) impedance error will not affect the noise figure.
On the TX side you will tune your PA for maximum power to the 
load that is actually present and that means that you compensate
for small impedance erroers.

If you really had a 0.2 dB loss (=4.7%) you would heat the power 
divider with 70W when running 1500W through it. It would get
really hot and that would surely not be normal.

In case you really want to know, run as much power as you can through 
the divider and check the temperature rise. Await thermal equilibrium,
in the order of 10 minutes. Then run 60Hz from a low voltage transformer 
through the outer tube or put a known power into the device by other
means and find out how much power you need for the same temperature
rise. My guess is that you would find that the thermal losses are
well below 0.2 dB. Probably something like 0.01 or 0.02 dB.

73

Leif / SM5BSZ