[amsat-bb] Re: Where can I buy pre-made feedline?
domenico.i8cvs at tin.it
Thu Dec 6 14:39:21 PST 2007
----- Original Message -----
From: "Dave Guimont" <dguimon1 at san.rr.com>
To: "Edward Cole" <kl7uw at acsalaska.net>
Cc: <amsat-bb at amsat.org>
Sent: Thursday, December 06, 2007 8:17 PM
Subject: [amsat-bb] Re: Where can I buy pre-made feedline?
> >I much prefer using N-connectors just about everywhere because of the
> >superior contact design. PL-259 is not a good connector above 2m and
> >is marginal at 2m. I wonder how this method of construction affects
> >use with very high power (1500w)? For satellite RF levels (<50w) it
> >may be OK.
> Ed, I agree with you for the additional good reason:
First of all the N connector has a constant impedance and it is usable up
to 12 GHz
The N connector has a reliable contact for the coax braid between the
N/male and the N/female even if the male is not perfectly screw up
in to the female
The N connector do not requires to solder the coax braid to the connector
The N connector can be used outside for years provided it is properly
banded with a good selfbonding electrical tape like Scotch 23
The N connector stands up to 1000 watt in 70 cm
On the other side:
The PL259 is not a constant impedance connector.
The real point of the electrical contact between the braid of the coax
connected to a male PL259 and the body of a female SO239 must be
the toothed ferrule located inside at the end of both but this contact
tend to oxidate particularly in the outside applications and in general
because the toothed contact is only relyed to the force used to screw up
the male PL259
If the male becomes a little bit loose screw than the braid becomes an
open contact or a contact with high resistance in series of it.
As a consequence the RF currents flowing inside the surface of the
coax braid tend to flow inside the threaded male lid but this longher path
only for the braid creates another impedance bump even if it is not
For the above mentioned reason I use only N connectors ad I replace
all PL259 with N connectors "when I can" in the existing equipments.
Best 73" de
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