I'm aware that the PL-259 has loss but what I'd
like to find out is how much loss at 146 & 450 mHz?

Anyone know?

Ken KG0WX

"Ken Bessler" wrote in message
news:uS7jd.15068$Vz4.14651@okepread01...
I'm aware that the PL-259 has loss but what I'd
like to find out is how much loss at 146 & 450 mHz?

Anyone know?

Ken KG0WX

It depends on a whole lot of factors, not least of which is the quality of the
connector and how accurately it is assembled. For 70cm, losses are typically
around 0.7 - 0.8 dB. This might not seen like a lot until the number of
connectors is added up.A base station with a main co-ax run, a socket
terminated antenna, and 2 co-ax tails has 4 connections. That adds up to 3dB,
or half your signal lost before you even look at the co-ax losses. By
comparasion, a quality N-type is less than 0.1dB.

I don't see what the mechanism would be for the 0.7 - 0.8 dB loss you
quote, even if the connector has a rather poor dielectric. And one with
a good dielectric like Teflon wouldn't have any way to cause loss other
than conductor skin effect resistance. If anything, I'd expect an N type
connector to be slightly (although inconsequentially) lossier due to its
smaller diameter center conductor.

What reference do you have that shows this kind of loss for a PL-259?
I'd like to look at the test methodology. I'd also like to hear some
kind of explanation as to why an N type connector should have less loss
than a PL-259.

A PL-259 will of course cause a greater reflection than an N type
connector, and this will produce a "mismatch loss" in a system, like a
lab test environment, where the source and load impedances are fixed.
But nearly any amateur antenna installation has some method of adjusting
the match to compensate, which eliminates power delivery reduction due
to mismatch. Then, only true loss is important, and I just don't see the
mechanism which would cause a PL-259 to be any worse than an N.

Roy Lewallen, W7EL

matt wilson wrote:

"Ken Bessler" wrote in message
news:uS7jd.15068$Vz4.14651@okepread01...
I'm aware that the PL-259 has loss but what I'd
like to find out is how much loss at 146 & 450 mHz?

Anyone know?

Ken KG0WX

It depends on a whole lot of factors, not least of which is the quality of the
connector and how accurately it is assembled. For 70cm, losses are typically
around 0.7 - 0.8 dB. This might not seen like a lot until the number of
connectors is added up.A base station with a main co-ax run, a socket
terminated antenna, and 2 co-ax tails has 4 connections. That adds up to 3dB,
or half your signal lost before you even look at the co-ax losses. By
comparasion, a quality N-type is less than 0.1dB.

Read he
http://www.qsl.net/vk3jeg/pl259tst.html

--

Regards,
Ivan

VE3IVM

"Ken Bessler" wrote in message
news:uS7jd.15068$Vz4.14651@okepread01...
I'm aware that the PL-259 has loss but what I'd
like to find out is how much loss at 146 & 450 mHz?

Anyone know?

Ken KG0WX

On Sat, 06 Nov 2004 16:35:44 -0800, Roy Lewallen
wrote:

|I don't see what the mechanism would be for the 0.7 - 0.8 dB loss you
|quote, even if the connector has a rather poor dielectric. And one with
|a good dielectric like Teflon wouldn't have any way to cause loss other
|than conductor skin effect resistance. If anything, I'd expect an N type
|connector to be slightly (although inconsequentially) lossier due to its
|smaller diameter center conductor.
|
|What reference do you have that shows this kind of loss for a PL-259?
|I'd like to look at the test methodology. I'd also like to hear some
|kind of explanation as to why an N type connector should have less loss
|than a PL-259.
|
|A PL-259 will of course cause a greater reflection than an N type
|connector, and this will produce a "mismatch loss" in a system, like a
|lab test environment, where the source and load impedances are fixed.
|But nearly any amateur antenna installation has some method of adjusting
|the match to compensate, which eliminates power delivery reduction due
|to mismatch. Then, only true loss is important, and I just don't see the
|mechanism which would cause a PL-259 to be any worse than an N.

I second Roy's comments.

The "UHF" connectors have many drawbacks: they are not constant
impedance, they are not waterproof, their mating is not repeatable and
they are difficult to assemble; however, they are not necessarily
lossier than other types.

It is difficult to prove this in a lab environment because there are
no traceable reference standards for this connector series. Thus,
between-series adapters are needed to measure them and adapters always
add uncertainty to the results.

Clearly though, by inspection it can be seen that for decent quality
materials and construction, there is no inherent loss mechanism that
would result in the highly inflated loss figures commonly bandied
about in ham radio circles.

Wes N7WS

On Sat, 6 Nov 2004 11:30:55 -0600, "Ken Bessler"
wrote:

I'm aware that the PL-259 has loss but what I'd
like to find out is how much loss at 146 & 450 mHz?

Anyone know?

Ken KG0WX




Looking at my Wirebook IV, pages 3.2 and 3.3

Alan Bloom, n1al, used an HP8753 RF network analyzer to compare losses
of UHF vs. N connectors.

Both connectors measured 0 db loss up to 100 mhz.

At 150 mhz, the N has 0 db loss, the UHF has .01 db loss.

At 450 mhz, the N has 0 db loss, the UHF has .09 db loss.

That's it...

Bob
k5qwg

Ah, yes, he's measuring "insertion loss" in a system with fixed source
and load impedances. This isn't only dissipative loss (although it can
include dissipative loss), but rather is the "loss" or reduction in
signal received at a fixed load. This reduction in signal is caused by
the combination of real, dissipative loss and that due to mismatch
between the source and load (known as "mismatch loss"). For example, if
you had a piece of completely lossless 75 ohm coax between the source
and load in his (typical lab) test setup, you'd measure 0 "insertion
loss" if the line was exactly a half wavelength long, 0.18 dB if the
line were exactly a quarter wavelength long, and other values depending
on the line length. This isn't due to any loss in the cable, but to
reduction in the signal dissipated in the load due to mismatch when
using a fixed source impedance.

If we put a matching circuit at either end of the coax, we can make the
"insertion loss" completely disappear, by restoring the impedance match.
In a typical amateur antenna installation, we do use a matching
arrangement to insure this impedance match. Therefore, any "insertion
loss" due to mismatch is eliminated. All that's left is any true,
dissipative loss. The mismatch loss VE3JEG measured is, I believe,
nearly solely mismatch loss.

I've posted a fair amount on this topic in the past. You should be able
to find the postings with a groups.google.com search of this newsgroup
for postings by me containing "mismatch loss" or "insertion loss".

Roy Lewallen, W7EL

Ivan Makarov wrote:
Read he
http://www.qsl.net/vk3jeg/pl259tst.html

--

Regards,
Ivan

VE3IVM

"Ken Bessler" wrote in message
news:uS7jd.15068$Vz4.14651@okepread01...

I'm aware that the PL-259 has loss but what I'd
like to find out is how much loss at 146 & 450 mHz?

Anyone know?

Ken KG0WX

Please see my comments to Ivan's posting, about the fact that "insertion
loss" is being measured in a fixed impedance environment. The same
comments apply here.

Interesting that N1AL got about 0.1 dB insertion loss at 450 MHz, while
VK3JEG got about 1.0. These measurements aren't easy to make, even when
you have the best equipment. But as I said in my comments, they're not
measuring dissipative loss anyway.

Roy Lewallen, W7EL

Bob Miller wrote:

Looking at my Wirebook IV, pages 3.2 and 3.3

Alan Bloom, n1al, used an HP8753 RF network analyzer to compare losses
of UHF vs. N connectors.

Both connectors measured 0 db loss up to 100 mhz.

At 150 mhz, the N has 0 db loss, the UHF has .01 db loss.

At 450 mhz, the N has 0 db loss, the UHF has .09 db loss.

That's it...

Bob
k5qwg

In article ,
says...


On Sat, 6 Nov 2004 11:30:55 -0600, "Ken Bessler"
wrote:

I'm aware that the PL-259 has loss but what I'd
like to find out is how much loss at 146 & 450 mHz?

Anyone know?

Looking at my Wirebook IV, pages 3.2 and 3.3

Alan Bloom, n1al, used an HP8753 RF network analyzer to compare losses
of UHF vs. N connectors.

Both connectors measured 0 db loss up to 100 mhz.

At 150 mhz, the N has 0 db loss, the UHF has .01 db loss.

At 450 mhz, the N has 0 db loss, the UHF has .09 db loss.

That's it...

Bob
k5qwg

For those who want to see Al's original USENET post from 1992:

From: (Alan Bloom)
Date: Fri, 18 Sep 1992 23:03:13 GMT
Subject: The Truth about UHF Connectors
Message-ID:
Organization: Hewlett-Packard, Santa Rosa, CA
Path:
dxis!batman!cs.widener.edu!eff!sol.ctr.columbia.ed u!spool.mu.edu!sdd.hp.c
om!scd.hp.com!hplextra!hpl-opus!hpnmdla!alanb
Newsgroups: rec.radio.amateur.misc
Lines: 64

Ya gotta feel sorry for UHF connectors. Recent strings on this notes
group lambasted them as worthless at VHF and above, and barely
tolerable at HF. One poster called them "5 dB attenuators", and
many agreed that there must be some sort of conspiracy among ham
equipment manufacturers to inflict such garbage connectors on the
amateur community.

Today I finally remembered to bring some UHF adapters from home so
I could do some relative measurements of UHF versus type-N.
As expected, the type-N showed lower insertion loss at high
frequencies, but the UHF connectors were hardly "5 dB attenuators."

For the test I connected an HP8753 RF network analyzer through
two short BNC cables into the following arrangement:
_______ ____________ ___________ ____________ _______
| | | BNC female | | N female- | | N male to | | |
__| 10 dB |__| to N male |__| N female |__| BNC female |__| 10 dB |__
| Atten.| | adapter | | adapter | | adapter | | Atten.|
|_______| |____________| |___________| |____________| |_______|

Then I repeated the measurement with the N adapters replaced with UHF.
I normalized the measurements by replacing the 3 adapters with a BNC
double-female. (That is, this was assumed to have 0 dB loss.)

Since two N or UHF adapters were used, I assume the loss per connector
is half the total. The vertical scale was .1 dB/division, so I
estimated the insertion loss to the nearest .01 dB or so:

--------- Type N ---------- ---------- UHF
------------
FREQ (MHz) TOTAL LOSS PER CONNECTOR TOTAL LOSS PER
CONNECTOR
1.8 0 dB 0 dB 0 dB 0 dB
30 0 0 0 0
100 0 0 0 0
150 0 0 .02 .01
200 0 0 .03 .015
450 0 0 .18 .09
600 0 0 .26 .13
900 0 0 .66 .33
1000 .05 .025 .8 .4
1300 .1 .05 .86 .43
1600 .05 .025 .5 .25
2000 .05 .025 .02 .01

Insertion loss increases until about 1200 MHz, and then starts to
decrease until it is almost zero for the UHF connector at 2 GHz!
At this frequency, the connectors are about 1/4 wave long (1 inch,
assuming .66 velocity factor), so I assume that the two adapters
are providing a conjugate match to each other. This confirms my
assumption that the insertion loss is due to reflections (impedance
mismatch), not absorption (true power loss).

Bottom line: UHF connectors work fine through the VHF range, and
are not too bad even on the 420 MHz band if you can stand about .1 dB
mismatch loss per connector.

By the way, I did not do the full 2-port calibration on the HP8753,
so there is a couple hundredth's dB ripple in the plots. I averaged
this out by eye to come up with the numbers in the above chart.

AL N1AL

P.S. Sorry, I guess I violated the Usenet rule against posting
objective data... :=)

--
+----------------------------------------------+
| Bob Schreibmaier K3PH | E-mail: |
| Kresgeville, PA 18333 | http://www.dxis.org |
+----------------------------------------------+

I'm glad to see objective data. But as I've said before, it's not
terribly relevant to typical ham radio antenna applications. It would be
very interesting if you would build a simple L matching network with as
low loss as possible (to mimic a ham installation) and repeat the
measurements, readjusting the matching network for each frequency and
connector to minimize the insertion loss. Then you'd be eliminating
mismatch loss from the measurement, and we'd see only the connector (and
matching network) dissipative loss. That's the only loss of concern in
an antenna system presuming you have a way to adjust the match.

Roy Lewallen, W7EL

Bob Schreibmaier wrote:


For those who want to see Al's original USENET post from 1992:

. . .

P.S. Sorry, I guess I violated the Usenet rule against posting
objective data... :=)