To: WICEN QLD Secretariat
From: Bill VK4XZ
Return
Subject: Proposed Standards for WICEN Qld.
I agree that WICEN QLD should
have a set of Standards to allow the inter-connect ability of equipment used by
WICEN Operators and Groups during activations and exercises. But, do bear in
mind that any proposed change from what already exist, will (a.) take time for
the person or group to change over and (b.) will cost money. However, don’t let
that deter you from the ideal.
This document will endeavour
to point out choices mainly in Co-ax connectors, Fuses and Power connectors but
briefly delves into other equipment.
A. Power
Connectors – 12 V DC.
1. 12 V Plugs & Sockets – 32V Polarised. (`T’
configuration)
Firstly, I still deem these old 32 V polarised P&S to be the better even though a little
bulky. I probably have about 10 around my shack. But nowadays at about $7 each they have lost
the custom of this old pensioner. Then of course, this then brings forth the
argument of which pins are the positive and the negative. If you belong to the
VK3 camp you will say that the vertical pin is positive and the horizontal is
negative. If you belong to the VK2 camp, you will say that the vertical pin is
negative and the horizontal (ie.`top
of the T’) is positive.
However, the SAA (Standards
Association of Australia) do have a standard which states – “Where the Extra Low
Voltage supply is referenced to earth, it is recommended that the radial
pin be the earth pin." And, of
course, the radial pin is the one pointing to the centre and as our 12 V vehicle
battery is tied to earth, thus the radial pin is negative and the horizontal (top
of the `T’) one is positive. Also it easy to remember as it is in step with the
3pin plug where the radial pin is also the earth pin. Thus I comply with that
standard and from the questionnaire that I sent out; only one person was
different to the SAA.
Known usage – my survey
showed that about 45% have them, but a number said that they were now too
expensive & they, too, were converting to the Auto type.
2. 12 V Plugs
& Sockets – Automotive Polarised.
(`T’ configuration)
Details – “Narva” brand, Male
2 Way Connector P/No 56252, Female 2 Way Connector P/No 56262. Apparently rated
22 Amps. They are automotive items & I buy from `Auto Pro’. Beware, there
are other brands that look similar but don’t really mate properly. And the
vertical pin is earth & the `top of the `T’’ is positive.
These plastic ones first came
to my notice when the new Yaesu came equipped with them, & then I also
found that a number of Brisbane WICEN people were already using them. I also
believe that Icom gear comes equipped with these. Yes
they are inexpensive. They are about 90c each and they are practical. I use
them on my own gear and have never had a failure. Only disadvantage is that
there is no such thing as a panel mount & you end up with a patch box with
a number of tails with a connector on them.
Scarc usage – We have adopted
them as the SCARC WICEN Standard. These are already installed on the Club
Station (approx. 14) and the SCARC WICEN Van (approx. 12). (I actually buy them
in packets of 10).
They should be both crimped
and soldered. And, of course, of the connectors, the female; the one with the non-exposed
connections is the hot side. The wire from the one with the pins showing runs
to the equipment via the fuse holders. And, like a 3 pin plug, the pin pointing
to the center ie.radial, is the ground or –ve & thus the flat one, or if
you like to say – the top of the “T” is +ve.
My mobile
patch box. Note above that I have
one 32V type(wired for 12V of course); just in case.
Known usage – my survey
showed that about 45% are using these with at least 69 known pairs. And if a
majority of those who are already using the 32V type do convert,
the numbers will increase for these Auto types.
3. 12 V Plugs
& Sockets –
I am aware that WICEN (NSW)
has adopted them as its standard 12V DC Power Connector for all operations and
installations. .
They are not
easily found in VK4 and if you do the cost will be in the region of $9-00 to
$10-00. I had not seen them until last
week when our Scarc Secretary showed me one. My survey revealed that only 3
WICEN people were using them. The advantage is that they are coloured. A perceived disadvantage is that plug &
socket do appear to come to come apart very easily & maybe if bumped or
stretched you could lose power. There appears to be a warning re usage ie.” The
4. 12 V Plugs
& Sockets – Other
I am aware of other types
(a).Those used for plug-in
lamps for vehicles such as firetrucks etc.with one pin larger than the other.
(b) The DC power connectors -
the small cylindrical type, pin goes inside +ve, outside is –ve; is useful for things like Handheld chargers etc, but
most would not consider them as a plug for a transceiver. Problem is that they
come in a number of sizes.
(c). Cigarette lighter plugs which
can often have intermittent contact especially if the spring contacts on the
outside of the plug does not make good contact with the metal strips within the
socket. I consider them to be the most unreliable of the all types.
However, all/any of these appear
to be in the minority and/or unreliable and thus we should not put amateurs to
the expense of purchasing them.
Recommendation:-
Automotive Polarised. (`T’
configuration) – “Narva” brand
Female P/No 56262, Male P/No 56252
Crimping & soldering of
the terminals is part of the standard.
Reason -
(a).
Existing & expanding usage in the amateur community,
(b) Economical Cost, $0-90 as
against $7-00 for 32V type or more for
(c) Ease of purchase – `Auto
Pro’ stores & others.
(d) Basically Idiot proof. – (But
maybe they’ll find a way?)
Whatever standard is adopted, we could follow the VK2 note – “Members who wish to adopt the new standard but don't want the expense of re-wiring all of their gear, may choose to simply make up enough adaptors, to adapt their own system to the standard”. (In my own case, I have an adaptor, but am slowly converting to the Automotive type, both my own gear and that of the Maleny SES & RFS ).
B. Fuses and
Connectors & Distribution.
There is a great variation in
fuse holders in the service. However, I have always found that - if the lead
from the equipment goes firstly to the fuse holders eg. 15 cm of wire, then another
eg.15 cm to the connector, it does not matter which type is used.
ie Equipment <======>Fuse
Holder<=====>Power Connector.
Fuses – 10 A 3AG is the most universally used.
And there should be fuses in
both the +ve & -ve leads. This really relates to automotive installations,
but since we sometimes change equipment from shack to vehicle, it’s a good rule
to follow. Imagine what happens if the lead from battery to chassis comes loose
– the starting current will attempt to find its way via the negative radio
lead, result - melt down – maybe even a fire – a fuse will prevent that.
Recommendation:-
All WICEN members be
encouraged to adopt the principle of
Equipment <======>Fuse
Holder<=====>Power Connector
Fuses 3AG type to suit
equipment.
Fuses in both the the +ve
& -ve leads.
C. Automotive
I believe that most already
connect direct to the 12V battery which of course is best practice. But I
always place a fuse holder (3AG) in the positive lead within 20 cm of the +ve pole.
This ensures that if ever the wire gets shorted through an accident or
whatever, then the fuse will blow rather than a fire be created. The rating of
the fuse should be greater than the sum of all equipment; I find that 25 A is
adequate as you do not transmit on all radios at once and 25 A blows on a short...
Recommendation:
All amateurs be encouraged to
run the power direct from the battery and to place a fuse holder & fuse in
the +ve lead within say 20 cm of the battery.
(This does not superceed
having 2 fuse holders & fuses close to each piece of equipment)
D. Co-Axial
Cable & Portable Antennas.
Having had the experience of
having a number of portable antennas with say 8 to 10 metres of co-ax affixed
to each, it soon became obvious that this was impractical. Thus now, I am
slowly converting my portable antennas to have either a female BNC co-ax
connector directly on the antenna or a half metre or less of co-ax with a female
BNC co-ax connector. Thus with just a couple of 10 metre co-ax leads with a male
connector on each end, I can change to different antennas without carrying
(& buying) great lengths of co-ax.
For portable/mobile, even at UHF, the losses
of 10 metres or less of RG58 does not give any significant degradation of
signal & much easier to carry.
Recommendation:
All amateurs be encouraged to
terminate their portable antennas with a co-ax connector close to the feed
point. And to use co-ax leads with connectors at each end. And
to carry suitable Co-ax adaptors.
E. Co-Axial
Cable Connectors.
1. The UHF Connectors – PL259/SO239.
First we
should remind you that UHF means `Universal High Frequency’ and not Ultra High
frequency. And you have already been told that they are not suitable for UHF.
Advantage is they have been around from day one and that is why there are lots
of them around. Fortunately, science has invented better types. Disadvantages
are 1. They tend to vibrate loose in a mobile situation. 2. The method of
making a connection of the braid of the co-ax to the connector by dropping some
solder through a few holes of a solder resistant chrome body leaves a heck of a
lot to be desired. 3. Even if you buy the expensive type where the braid is
compressed by a washer within the connector to make a good termination, you
still have that `lumped’ inductance there at VHF & UHF.
2. The `N Type’ Connectors
Regarded by most as the best. It is pleasing
to note that Amateur equipment manufacturers are now fitting them to gear. The
big advantage of them is they maintain constant impedance through the
connector. The disadvantages are they are a little too big for mobile use and
they are expensive costing up to $10-00 for a good quality plug.
3. The BNC Connectors
These run a close second to the `N Type’.
Actually the internals are exactly the same as an `N Type’, & thus still
have the constant impedance advantage. It appears to be the industry standard
for commercial transceivers of the mobile and low powered variety (except for
those that use the SMA). They are designed to fit well with RG58 co-ax, but you
can buy them for RG213 in both solder & crimp. The only disadvantage is the
solder types are a mongrel to fit. But the crimp type can be fitted within
minutes. The crimping tool cost around $50-00, so if you are fitting a lot then
it’s worth the money. For the others, there are quite a few around and it’s not
hard to persuade the owner to fit for you. The writer has a crimp tool and is
gradually converting his UHF type to BNC’s and in fact has replaced a couple of
UHF sockets on the transceivers with BNC sockets. For the remainder, he uses a
PL259 to BNC adaptor. The addition of a coloured `boot’ is a great enhancement.
Scarc usage – We have adopted them as the SCARC WICEN
Standard. These are already installed on the Club Station (approx. 30) and the
SCARC WICEN Van (approx. 14).
EMQ usage – As EMQ/SES have
commercial gear, most is fitted with BNC’s. We will be recommending to them
that they install amateur VHF & UHF antennas and naturally these will
terminate in BNC’s. Be prepared if you are requested to take your radio &
operate in their Comms Room.
4. Other RF Connectors.
The SMA’s
deserve a mention but firstly they do not appear have the wattage rating of the
PL259, or N type or the BNC. Secondly the whole family has been thrown into
confusion by the reverse type. Thirdly, the ones sighted are only used on
handheld gear. Thus they are not common & cannot be recommended.
The TNC is actually a BNC with a screw cover for attachment. Just as
good as the BNC but rarer in commercial service & thus, again, cannot be
recommended.
A Word about Power Ratings for Co-ax Connectors.
I thought someone would say that some types would not handle the power, so I asked a Professional. The answer was - Quote:-“It depends on frequency and temperature.100% power to 25 degrees C.80% to 50 degrees C.
0% at 155 degrees C.
N type:8 kW up to 10 MHz.
4.75 kW at 20 MHz.
Just over 4 kW at 30 MHz.
Just over 2 kW at 100 MHz.
1 kW at 400 MHz.
900 watts at 500 MHz.
180 watts at 10 GHz.
The BNC is roughly the same...Believe it or not the humble PL259 is better at low, low frequencies.They are no good above VHF.Now as a rider to all this... The connectors have to be made to mil-spec.Disregard all of the above if you buy cheap unmarked connectors”.-unquote.
Recommendation:-
The recommendation is for the
BNC type.
1. Good impedance quality –
equal to N type & exceeds PL259.
2. Easy to attach/detach –
great for mobiles - no loose connectors.
3. Positive braid connection;
particularly crimp type.
4. Economical cost – around
$2-50 - Better priced than N type
5. Most commercial
transceivers use these, thus all cable connectors alike.
6. Ease of assembly with
crimping tool.
7. A significent
percentage of amateurs are already using BNC’s.
I believe the following also applies also to Co-ax Connectors – “Whatever standard is adopted - `Members who wish to adopt the new standard but don't want the expense of replacing all of their connectors, may choose to simply purchase enough adaptors, to adapt their own system to the standard”. (In my own case, I have some adaptors, but am slowly converting the UHF type to BNC).
Signed
Bill Sebbens VK4XZ