[TowerTalk] measuring old coax, return loss ?

[Leeson]

Note that the return loss measurement should be made with an open, short 
or non-dissipative reactive load, not a dummy load.

Dave, W6NL/HC8L

On 5/8/24 10:15 AM, David Hachadorian wrote:
> I use an SWR meter or antenna analyzer connected to the unterminated 
> coax.  Tune the analyzer to the upper end of its frequency range, e.g. 
> 30 or 50 MHz.
> 
> Loss = 10 Log ((SWR+1)/(SWR-1))
> 
> After determining the loss in the OLD cable, you can look up the loss in 
> the equivalent length of NEW cable, and decide whether you can live with 
> the difference.
> 
> This method can even be used with an antenna connected at the far end. 
> Just tune the analyzer for maximum SWR in the 20-50 MHz frequency range 
> and do the calculation at that frequency.  By doing the measurement at 
> the frequency of max SWR, the antenna is essentially disconnected.  By 
> using the analyzer at the upper end of its frequency range, inaccuracy 
> in the measurement of high values of SWR are minimized.
> 
> Dave Hachadorian, K6LL
> Yuma, AZ
> 
> 
> 
> On 5/8/2024 9:42 AM, Jamie WW3S wrote:
>> What is a good way to test older coax? return loss? I am seeing 12, 
>> almost 13 db return loss into a dummy load, with about 55 ft of coax, 
>> good, acceptable or ?!?!?!?!
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