"Gary Smith" wrote in
:

Yes, i am in rural Southwest Victoria. I am currently running a
discone on 2 Metres which is about 5 Metres above ground.
The closest 2 Metre repeater is approx 100Km line of site and has big
problems with RX, as such i cannot access it with my current antenna.

Gary, 100km is a long path to a repeater, so you have to make sure you
are doing some things right.

I don't want to be negative about your discone, but they, being very
broadband, accentuate IMD problems (so called pager interference) with
receivers. If you are in the sticks, that won't be as noticeable as in
the city, and it will affect ham gear more than commercial LMR which tend
to have better front end selectivity. The other thing about the discone,
is it is relatively low gain on tx.

I note that your main problem with the 2m repeater is it hearing you, so
you should be trying initially to boost your transmit signal. Perhaps you
should look around at one of the commerical high gain 2m or dual band
antennas that will give you 3 - 6dB lift depending on the model (in other
words to double to quadruple your effective radiated power). Review your
feedline situation to see you are not chucking signal away there as well.
Another alternative is to build or buy a small yagi, 4 to 6 elements,
vertically polarised and fixed on the repeater, but of course it is a bit
restrictive for other contacts.

I have a 20 element yagi on UHF CB with a repeater to the Southeast
and us locals use that repeater to communicate as we have for years,
and its our local link, still, at this stage. So, we're not all
surrounded by repeaters in our back yards in this corner of this state

Repeaters aren't everything, I think there are 9 or so here for a
relatively low ham population, I don't use them, and they aren't very
busy except for drive time when they sound a bit like CB.

and the terrain isn't all flat either, our town is built on the
Glenelg river and fortunantly i live a little higher than the centre
of town. We still have non amateur friends on UHF CB and like to keep
in touch with them. I pitty those that use UHF CB repeaters in or near
cities, usually it's a waste of time talking on them but there are
SOME good operators there as well. "in the sticks" we use them for
proper conversations instead of kids trying to overpower each other.
Maybe thats why you are wondering why i still want UHF CB

Have fun, try experimenting with some different antennas, reserve your
discone for a radiating dummy load.

Re the Commodore, when I was younger, the deal was that the car owner
purchased a slab, invited some competent mates around and after a certain
anaesthetic threshold was reached, the holesaw came out and the antenna
was installed... just watch that the guy with the holesaw isn't as
anaesthetised as a newt!

Owen

Thanks Owen, Yes, i know the discone is low gain, and i have (Shock, Horror)
approx 60 ft of rg58 connected to it :
I have been playing with radio for about 20 years but only just aquired my
Ham ticket. I have read the ARRL handbook around 5 times now i would say,
cover to cover.

I am modifying an ex CFA "Polar" 163.2 MHz vertical at the moment, there are
plans on the net to modify this antenna to 146 meg. For those wanting to
view this pdf, google vk3cmc cfa. I am also going to price tubing for a 17
element 2 Metre Yagi and later on one for 70cm. Combined with some RG-213 i
think that will be quite fine, another station further away than i am is
getting into the repeater with a 6 element. My tower will be going up soon,
got a 50ft and 75ft so debating which one to use. 75ft is narrower inner
section (3 stage tilt over crank up) so would not hold as much weight and
wont take my KR400 inside the top section (too narrow).

I have the discone as a way to get up and running, can use the Mount Gambier
repeater with it all the time and that one is around the same distance AND a
large hill between it and me.. Most repeaters for us are around 60-100k +.
we have members all over the corner of the state and would be stuffed
without repeaters, fantastic things!!

Anyway, back to my ex CFA antenna...


Gary
VK3LCD




"Owen Duffy" wrote in message
...
"Gary Smith" wrote in
:

Yes, i am in rural Southwest Victoria. I am currently running a
discone on 2 Metres which is about 5 Metres above ground.
The closest 2 Metre repeater is approx 100Km line of site and has big
problems with RX, as such i cannot access it with my current antenna.

Gary, 100km is a long path to a repeater, so you have to make sure you
are doing some things right.

I don't want to be negative about your discone, but they, being very
broadband, accentuate IMD problems (so called pager interference) with
receivers. If you are in the sticks, that won't be as noticeable as in
the city, and it will affect ham gear more than commercial LMR which tend
to have better front end selectivity. The other thing about the discone,
is it is relatively low gain on tx.

I note that your main problem with the 2m repeater is it hearing you, so
you should be trying initially to boost your transmit signal. Perhaps you
should look around at one of the commerical high gain 2m or dual band
antennas that will give you 3 - 6dB lift depending on the model (in other
words to double to quadruple your effective radiated power). Review your
feedline situation to see you are not chucking signal away there as well.
Another alternative is to build or buy a small yagi, 4 to 6 elements,
vertically polarised and fixed on the repeater, but of course it is a bit
restrictive for other contacts.

I have a 20 element yagi on UHF CB with a repeater to the Southeast
and us locals use that repeater to communicate as we have for years,
and its our local link, still, at this stage. So, we're not all
surrounded by repeaters in our back yards in this corner of this state

Repeaters aren't everything, I think there are 9 or so here for a
relatively low ham population, I don't use them, and they aren't very
busy except for drive time when they sound a bit like CB.

and the terrain isn't all flat either, our town is built on the
Glenelg river and fortunantly i live a little higher than the centre
of town. We still have non amateur friends on UHF CB and like to keep
in touch with them. I pitty those that use UHF CB repeaters in or near
cities, usually it's a waste of time talking on them but there are
SOME good operators there as well. "in the sticks" we use them for
proper conversations instead of kids trying to overpower each other.
Maybe thats why you are wondering why i still want UHF CB

Have fun, try experimenting with some different antennas, reserve your
discone for a radiating dummy load.

Re the Commodore, when I was younger, the deal was that the car owner
purchased a slab, invited some competent mates around and after a certain
anaesthetic threshold was reached, the holesaw came out and the antenna
was installed... just watch that the guy with the holesaw isn't as
anaesthetised as a newt!

Owen

"Gary Smith" wrote in
:

Thanks Owen, Yes, i know the discone is low gain, and i have (Shock,
Horror) approx 60 ft of rg58 connected to it :

Yeah, ouch. Here is the bad news, if the discone VSWR is 1.5:1 (at the
antenna) and you have 60' of RG58, you are losing 58% of your transmitter
power in the feedline. With RG213 you would lose about 30% and with LDF4-
50 you would lose around 11%. The picture is worse with increasing
frequency.

Now you can offset the loss of transmitter power with an amplifier or
another 4dB of antenna gain, but noise levels should be so low in
Casterton that you will not recover the loss of receive performance
without an LNA (preamp) at the antenna.

If you want to work some line loss solutions, try
http://www.vk1od.net/tl/tllc.php .

Before I you get you carried away with LNAs, the following article might
be a bit technical, but it has some summary graphs that might convey the
idea: http://www.vk1od.net/gt/index.htm .

Something else to keep in mind, with an FM receiver, a 1dB increase in
strength of a noisy weak signal will result in much more than 1dB
improvement in Signal/Noise ratio. Improvements to your EIRP have the
same effect at the remote receiver.

I have been playing with radio for about 20 years but only just
aquired my Ham ticket. I have read the ARRL handbook around 5 times
now i would say, cover to cover.

I am modifying an ex CFA "Polar" 163.2 MHz vertical at the moment,
there are plans on the net to modify this antenna to 146 meg. For
those wanting to view this pdf, google vk3cmc cfa. I am also going to
price tubing for a 17 element 2 Metre Yagi and later on one for 70cm.

That is a huge antenna, 17el on 2m! You are talking about a 10m boom.
Gee, that will be a challenge horizontally polarised, but a bigger
challenge if vertically polarised. Have you thought about two yagis
stacked in the H plane, and supported so that you can swing them from
horizontal to vertical polarisation?

BTW, if you are interested in DL6WU designs for a long boom yagi, and
they are probably a good place for a beginner to start, see
http://www.vk1od.net/dl6wu/index.htm .

Combined with some RG-213 i think that will be quite fine, another
station further away than i am is getting into the repeater with a 6
element. My tower will be going up soon, got a 50ft and 75ft so
debating which one to use. 75ft is narrower inner section (3 stage
tilt over crank up) so would not hold as much weight and wont take my
KR400 inside the top section (too narrow).

High towers means longer coax... you might be looking at LDF4-50 sooner
than you think, especially for 70cm and 477MHz.


I have the discone as a way to get up and running, can use the Mount
Gambier repeater with it all the time and that one is around the same
distance AND a large hill between it and me.. Most repeaters for us
are around 60-100k +. we have members all over the corner of the state
and would be stuffed without repeaters, fantastic things!!

Anyway, back to my ex CFA antenna...

That should be an intesting project. You will see first hand what is
inside the radome, and understand why poor implementations are prone to
fatigue failure.

Owen