[Elecraft] UHF connectors [was: Array Solutions Lightning Arrestor]

[Alan]

Hi Al,

Yes, but don't forget that the connector "loss" is a mismatch loss, not 
absorptive power loss.  In other words, it affects the SWR slightly but 
does not actually absorb any power.

If you are using any kind of antenna tuner and tuning for 1:1 SWR, 
mismatch "losses" have no effect.  Even if you aren't doing that, the 
antenna is probably not a perfect 50-ohm resistive load anyway, so the 
connectors' mismatches are about as likely to make the SWR better as 
worse, depending on the phase and magnitude.

But the general point is sound.  Power loss is even more important for 
QRP than for QRO even though the  number of watts of loss is less.  When 
the other station can barely hear you, every dB counts!

Alan


On 02/11/2018 11:49 AM, Al Lorona wrote:
> Excellent. Thank you, Alan. Data for this particular measurement are very difficult to find on the web -- of course it took an ex-HP guy to do it!
> 
> Times Microwave (a manufacturer of coaxial cable) says 0.01 dB per UHF connector pair (PL-259-to-SO-239) at HF; I have seen other private measurements that estimate 0.02 dB; and now this data from N1AL. I usually take the greater of these, 0.02 dB, as a worst-case number. But Alan's measurements pretty much show that the loss at HF is almost too small to measure-- even if he had performed a full two-port cal.
> 
> Even so, you might be surprised to see how quickly it can add up. Beginning at the transmitter output (or receiver input) it is not uncommon to find 20 or more UHF connections in the path to the antenna. Using the 0.02 dB worst-case figure, that's at least 0.4 dB, or 9% of your power. I wouldn't worry about that but I know there are folks on here that would be bothered by that.
> 
> This, of course, is not counting loss in cables, filters, lightning arrestors, power meters, bulkheads, switches, antenna tuners, baluns, amplifier through-paths, transmission lines, etc. These can add another dB or more to the total and far outweigh any loss in UHF connectors. If you want to minimize losses, UHF connectors are the last thing you should worry about.
> 
> I encourage you to do an analysis to determine your system efficiency. I recently did so and discovered that I have a worst-case loss (to the feedpoint up at the antenna) of 1 dB, which is 21% of my power. Gone. Forever. Whoosh!
> 
> 
> Al  W6LX
>