-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

In writes:

On Mon, 26 Mar 2012 01:45:59 EDT, (Alan)
wrote:

In article Channel Jumper writes:

DrTeeth;788676 Wrote:


But I've
not considered BNC, at least for HF work.

Though it may be an impure thought, but don't HF commercial rigs all
have SO 259s? Are adapters available?
--

Cheers



Yes - but the adapters are quite lossy.


Actually, I have not found significant loss in any of these adapters
I have used. If they had much loss, they would get warm (or hot) when
transmitting, and none I have used do.

Alan

I agree with Alan. The adapters are not lossy.
I use them frequently to connect the outputs of my handhelds (BNC,
SMA) to mag-mount antennas (UHF connector). They work fine. Good
output signal and good reception. No heat generated.

Dick Grady, AC7EL

To respond to me privately, email to:
My Call at My Call dot org


Reading around on the subject, it seems that there are different kinds
of losses in connectors and transmission lines, and not all of them will
cause heating at the junction or interval where the loss occurs. Some
knowledgeable amateurs have noted that we sometimes confuse transmission
losses and insertion losses. Transmission loss, either Ohmic resistance
or dielectric, will be dissipative, and directly heat the transmission
line where the losses occur. Insertion loss, such as from impedance
mismatch, results in power being reflected. Even impedance-matched
connector conversions (50 Ohm to 50 Ohm) may still result in some
impedance mismatch due to practical limits on their physical design,
including their actual non-constant impedance that can vary with
frequency, and the quality of their connections, particularly after
long-term exposure to the elements. This is where the imaginary part of
complex impedance, also known as reactance, comes in.

Now, that reflected power has to go somewhere, and will either be
reflected back to the airwaves on reception, or back into the
transmitter on transmission. But just measuring heat generated at the
connector may not account for all losses, because the actual
dissipation may occur elsewhere. You may not have noticed much or any
signal loss due to operating well within usable link budgets, nor
noticed much extra heat generation in the body of the HT, but insertion
loss from connectors can contribute a small, measurable amount of
reduction in signal strength. Probably not something to worry about for
an HT talking to a repeater. Perhaps something to worry about for
Earth-Moon-Earth at UHF, or mountain-topping at microwave frequencies,
or other weak-signal work much above HF.


Some links I found on the subject:


1. Pretty Lousy? (PL) 259 Connectors

"The underlying assumption with the above statement is connector
loss has everything to do with resistive 'heating' losses, has
nothing to do with reflective losses, and all loss will reveal
itself as heat energy."

http://www.hamradio.me/connectors/pr...-the-test.html


2. The UHF type connector under network analysis

"Manufactures of UHF plugs and receptors all state that this type
connector are of non-constant impedance and are suitable for use
up to 200 or 300 MHz, depending on production quality. They also
state that the UHF connector can be used up to 500 MHz with a
cautionary note of reduced performance."

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


3. Insertion Loss vs. Transmission Loss

"Insertion Loss and Transmission Loss are often confused by hams."

http://vk1od.net/transmissionline/concept/iltl.htm


4. N-type vs. SO-239 NO FIGHTING PLEASE! :-)

"There's no question that Type N connectors will outperform UHF
connectors at VHF and UHF. But unless you're prepared to open up
the radio and replace the SO-239 with a Type N, don't sweat the
single connection. Just use a UHF-Type N adapter on the back of
the rig and go with Type N connectors everywhere else."

http://www.eham.net/ehamforum/smf/in...c=68629.0;wap2


5. Insertion loss for RF connector adaptors

"1/4 to 1/2 db per connector is the loss I've always heard."

http://www.amsat.org/amsat/archive/a.../msg00214.html


- --
73, Paul W. Schleck, K3FU

http://www.novia.net/~pschleck/
Finger for PGP Public Key

-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.5 (SunOS)

iD8DBQFPcK1K6Pj0az779o4RAoL7AJ9VQovYNqZnQP4W22CC2a 2061sFnwCgmdMN
VIgz18pm+vorQe1TZN466tQ=
=LMnT
-----END PGP SIGNATURE-----