[UK-CONTEST] connectors
dale.harvey at eddystone-broadcast.com
dale.harvey at eddystone-broadcast.com
Sat Feb 4 13:11:37 PST 2012
I have not seen power rating data for N or UHF connectors although I'm sure it's out there somewhere. Professionally, for continuous service, FM band II TX manufacturers stop at 1kW but that's pushing it as the mating surfaces of the N connector are the same as those of BNC and TNC and could fail under either voltage or current under mismatch conditions. UHF connectors are better, but the impedance is not defined so they're not ok above 30MHz really. All my first home brew equipment used Belling Lee (TV) connectors which are even worse! For powers up to 4kW I would look at 7-16 DIN series which although designed for cellular use are properly power rated (even 1kW at 1GHz). Because they are used so widely, the price for standard connectors is reasonable.
On another subject... I'm rarther glad the snow's arrived, now I don't have to go out for AFS tomorrow! Dale - G3XBY
Sent from my BlackBerry® smartphone on O2
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Today's Topics:
1. Re: PL259 connectors... (Ian White GM3SEK)
2. Re: Coaxial Connectors (Giles Herbert)
3. Re: Coaxial Connectors (David)
4. MRF 422s (Robin Thompson)
5. 432MHz AFS Contest - Final Leg of AFS Superleague (Bob Edgar)
6. Re: 432MHz AFS Contest - Final Leg of AFS Superleague
(Ian - G0GRI)
7. Re: 432MHz AFS Contest - Final Leg of AFS Superleague
(Robert Chipperfield)
----------------------------------------------------------------------
Message: 1
Date: Sat, 4 Feb 2012 14:32:32 +0000
From: Ian White GM3SEK <gm3sek at ifwtech.co.uk>
Subject: Re: [UK-CONTEST] PL259 connectors...
To: uk-contest at contesting.com
Message-ID: <M+uzvpJAGULPFAt5 at ifwtech.co.uk>
Content-Type: text/plain;charset=us-ascii;format=flowed
Reg wrote:
>I would not use petrolume jelly. I would use vulcanise tape and denso.
There are two types of "Denso" tape, though. One is the greeny-brown
stuff that used to be called Sylglas - completely waterproof but
horrible to use.
The other is dead black, looks like a very thick PVC tape with a
non-stick interleaving sheet, but is actually mouldable like putty. This
is the best I've ever used - totally waterproof, sticks instantly to
itself and to PVC, bare metal and many other surfaces, but does not
stick to your hands. This too is made by Denso, but it only seems to be
commercially available as an aluminium backed flashing tape.
The same material is also available as an accessory for Andrew cables,
eg as part of a ground clamp mounting kit where it is used to seal over
where the jacket has been cut away.
This mouldable black tape is absolutely not to be confused with
Coax-Seal, which is a different and very inferior product (and also very
messy).
>As for pl259 on hf they are fine. As long as others have said you buy
>decent ones. The larger centre pins on pl259s. Make them better to take
>high power. For all of you running 1.5kw from your amps as you cant
>afford decent feeder cable! I did once see the result of running a good
>amount of power into an n type with a mismatch. It was a charred lump.
>
The type N coaxial fuse. If everything is perfect, they will handle as
much as 1.5kW at 70cm... but that is a very big "if".
GL with the snow. Over here on the Wet Coast it's just normal heavy
rain.
--
73 from Ian GM3SEK
http://www.ifwtech.co.uk/g3sek
------------------------------
Message: 2
Date: Sat, 4 Feb 2012 14:42:05 +0000
From: Giles Herbert <g0nxa at hotmail.co.uk>
Subject: Re: [UK-CONTEST] Coaxial Connectors
To: Ray Hills <g3hrh at btinternet.com>, Contest Reflector
<uk-contest at contesting.com>
Message-ID: <BLU160-W18B7EE6426753BD7C0865DB2760 at phx.gbl>
Content-Type: text/plain; charset="iso-8859-1"
Ray,
C types can be bayonet or screwed. The "C" defines the insulator and conductor shape in the mating halves and is applicable to both mechanical arrangements for latching them.
I too used these in the BBC on IF cables on analogue Microwave links. In this case they were the screwed variety. The disadvantage of these was discovered in the winter when a cable needed to be used to monitor the IF on a mobile link on the roof of a frosty vehicle or on top of an icy domed top to a water tower! Ice in the fine threads made for inventive swearing and chilly fingers!
Giles Herbert
G0NXA
> From: g3hrh at btinternet.com
> To: uk-contest at contesting.com
> Date: Sat, 4 Feb 2012 12:40:27 +0000
> Subject: [UK-CONTEST] Coaxial Connectors
>
> Been following the discussion with interest. I agree that pressure sleeve
> connectors are preferred in all cases. I use 259s on HF and have had no
> problems with PS types. Same goes for N-type. Earlier PS versions do not
> trap the outer significantly well and can work loose in time. The current
> version uses a "top hat" slid between braid and insulant and gives a much
> better mechanical joint. The problem with soldered outer types is that by
> the time the solder has taken hold, the insulant has softened and can leave
> the pin off-centre and maybe even pulled out. The only ones that seem to
> avoid that trap are those with PTFE insulant.
>
> I also use RG213 cable for high voltage DC conections with PL259
> plugs/sockets. Seems fine up to 2.5 kV with good quality connectors. The
> cheapo's with "bakelite" insulators do flash over but PTFE ones are OK. But
> even so do not rely on the outer as the sole DC return path. A separate
> bonding earth between PSU and TX etc is an essential safety feature.
>
> No one has mentioned C-type connectors. When I was at the BBC (moons ago)
> we used them on all low power Band II and Band III equipments. I built up
> quite a collection and use them here for 144 MHz (but N-type for 432). They
> are a "bayonet" plug which with a quarter turn on the sprung outer ring
> locks over two studs on the socket. Particularly useful on my patch panel
> which has a built-in Bird coupler element and requires a lot of lead
> changing between bands. Much easier to use than N-type where I find the
> pitch of the outer thread so fine that cross-threading can occur unless very
> careful. Maybe that is due to increasing clumsiness with age, of course?
>
> Like the BNC the C-type comes in 50 and 75 ohm versions so check the pin
> diameter.
>
> Ray G3HRH
>
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------------------------------
Message: 3
Date: Sat, 4 Feb 2012 14:58:01 -0000
From: "David" <g3yyd at btinternet.com>
Subject: Re: [UK-CONTEST] Coaxial Connectors
To: "UK-Contest at contesting. com" <UK-Contest at contesting.com>
Message-ID: <00dc01cce34d$63ec76d0$2bc56470$@com>
Content-Type: text/plain; charset="US-ASCII"
I suspect the limit on a PL259/SO238 combination with PTFE insulation is
when the coax dielectric melts. PE has a lot lower thermal limit than PTFE.
Similar would apply to the N type plug/socket.
The skin effect would cause more connector heating for the same power as
frequency increases.
However unless you have a three phase power supply and a large rack sized
linear I doubt if either connector type would be a limiting factor on HF. If
you are worried could go to LDF5-50 and DIN connectors...
But for real power the local MW TX site runs TXs at 1600Kw PEP. Probably
plumb the feeder in to the TX with no connectors.
73 David
-----Original Message-----
From: uk-contest-bounces at contesting.com
[mailto:uk-contest-bounces at contesting.com] On Behalf Of Chris Tran GM3WOJ
Sent: 04 February 2012 13:40
To: uk-contest at contesting.com
Subject: Re: [UK-CONTEST] Coaxial Connectors
Hello all
I've been driven inside by heavy rain, so here is my 50p worth about coax
connectors...
There are different qualities of 'pressure seal' PL259 plugs - some poorer
quality ones have thin metal for the threaded ring that tightens onto the
socket and if you over-tighten them they fall apart - the threaded ring
separates from the body of the plug.
Despite the official power rating of N-types being 5kW, some well-respected
websites indicate that, from experience, they should not be used above 1kW -
the centre pin is inadequate. Assuming 50 ohms, 400W = 2.8A, 1500W = 5.5A,
10kW = 14.1A
I remember BBC antenna expert Mark GM4ISM telling me years ago that, if
correctly fitted and terminated, a PL259 was good for 10kW. (intermittent
service I assume!)
73
Chris
GM3WOJ
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------------------------------
Message: 4
Date: Sat, 4 Feb 2012 17:00:03 -0000
From: "Robin Thompson" <robin at g3tkf.co.uk>
Subject: [UK-CONTEST] MRF 422s
To: <uk-contest at contesting.com>
Message-ID: <014e01cce35e$704ff120$50efd360$@g3tkf.co.uk>
Content-Type: text/plain; charset="us-ascii"
Slightly off topic , but -
My beloved FT1000D has stopped producing RF !
Turns out one of the MRF 422s in the p.a. has an o/c base - the other
appears to be fine - and the biasing looks ok.
What is the expert opinion - should both be replaced or is it ok to replace
just the one ?
Does anyone know a reliable source of MRF422s in the UK ? or does anyone
have one !?
73
Robin
G3TKF
City of Bath
------------------------------
Message: 5
Date: Fri, 3 Feb 2012 23:14:06 -0000
From: "Bob Edgar" <bobedgar.radio at gmail.com>
Subject: [UK-CONTEST] 432MHz AFS Contest - Final Leg of AFS
Superleague
To: "UK Contesting" <uk-contest at contesting.com>
Message-ID: <CF05583691CF4DF38E04507D512B23B7 at edgar2>
Content-Type: text/plain; charset="iso-8859-1"
HI all,
The RSGB 432 AFS Contest takes place this Sunday (4th Feb) from 0900-1300 UTC. This contest is the final leg of the 2011/2012 AFS Super League.
Exchange is RST, Serial Number and locator. Scoring is 1 point per kilometre, with no multipliers.
There are two secions: Open and Single Operator Fixed.
AFS Rules apply, although non-club entries are accepted in the individual sections.
Details at http://www.rsgbcc.org/
Bob G0KYS
RSGB Contest Committee
------------------------------
Message: 6
Date: Sat, 4 Feb 2012 19:31:57 +0000 (GMT)
From: Ian - G0GRI <ian.g0gri at btinternet.com>
Subject: Re: [UK-CONTEST] 432MHz AFS Contest - Final Leg of AFS
Superleague
To: Bob Edgar <bobedgar.radio at gmail.com>, UK Contesting
<uk-contest at contesting.com>
Message-ID:
<1328383917.52694.YahooMailNeo at web87015.mail.ird.yahoo.com>
Content-Type: text/plain; charset=utf-8
Snow here, a lot of roads poor and only just gritting in last 2 hrs.
I guess a lot of the /p stations may not be on due to conditions
Anyhow good luck to those that do take part
Ian
G0GRI
------------------------------
Message: 7
Date: Sat, 04 Feb 2012 19:34:48 +0000
From: Robert Chipperfield <robert at syxis.co.uk>
Subject: Re: [UK-CONTEST] 432MHz AFS Contest - Final Leg of AFS
Superleague
To: Ian - G0GRI <ian.g0gri at btinternet.com>
Cc: UK Contesting <uk-contest at contesting.com>
Message-ID: <4F2D8858.6030908 at syxis.co.uk>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
We're looking outside anxiously here in Cambridge.
All being well, active as G3PYE/P and M0VFC/P, but that could change
depending on what it looks like in the morning...
Fingers crossed, and good luck everyone who does brave the weather!
73,
Rob, M0VFC
On 04/02/2012 19:31, Ian - G0GRI wrote:
> Snow here, a lot of roads poor and only just gritting in last 2 hrs.
> I guess a lot of the /p stations may not be on due to conditions
> Anyhow good luck to those that do take part
> Ian
> G0GRI
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