Roy,
I don't have any "real" reference to the connector loss, just
folklore. I took the cable loss from the same source as you - if
there is error chalk it up to sloppy reading of the graph 8-} I do
see that we both quoted the same 1 dB of cable loss, that tells me I'm
on track. I did re-read my 'guesstimate' of power loss in the cable
and it does look like my math is off a bit.

I agree with what you say regarding the loss not being enough to
notice and thanks for steering me straight on the connector loss.
Personally, I've never tried to measure connector loss nor have I gone
obsessive-compulsive about changing everything to BNC or N connetors,
I just don't see any return on the effort for 2 meters. I use
PL-259's with the exception of antenna's that have N connectors; have
never fretted the "folklore" impedance bump issue either - just
concentrate on making a solid connection and not melting the
dielectric when soldering the braid to the shell, then follow with
good weatherproofing.

Howard
On Thu, 16 Oct 2003 23:19:57 -0700, Roy Lewallen
wrote:

What kind of connector has 0.5 dB loss at 2 meters? And what's the loss
mechanism? Is there some kind of connector out there filled with carbon
or something? Who made the measurements and how?

The ARRL Antenna Book shows RG-58/U and RG-58B/U (plain copper center
conductor) as having just under 6 dB/100' attenuation at 2 meters, and
RG-58A/U and RG-58C/U (tinned copper) as about 6.5 dB/100'. I checked a
100' piece of RG-58C/U in my junk box and found it to be 5.6 dB/100' at
146 MHz. So I'd expect 20 feet or so to have just over 1 dB of
attenuation, almost certainly not enough to notice except perhaps just
barely, if you were right at the noise level. Certainly it wouldn't be
noticeably improved by using some other kind of cable.

Oh, and that measurement was made with BNC connectors on both ends. The
loss of those connectors shouldn't be measurable except with extremely
sensitive equipment.

Roy Lewallen, W7EL

Howard wrote:

How do you figure a 3 dB loss? A mobile installation 'typically' uses
RG-58 which at 2 meters has about 4.5 dB loss per 100 feet and most
mobile antenna's come with 15 - 20 feet of cable. As I see it, that's
about 1 dB loss (or thereabouts) for the cable and I've seen connector
loss figures hover around 0.5 dB. At a 1.5 dB loss roughly 1/4 of the
signal is not unreasonable which would put it at the 40 watts you
mention. I don't [totally] aruge your conclusion - just your 3 dB
assertion.

Am I missing something?
Howard