[TowerTalk] RE- best repeater configuration - Looking for more suggestions
Randy Molyneaux (ve5 rjm)
ve5rjm at hotmail.com
Sat Jan 6 10:03:57 EST 2007
******************************************************
I beleive I will be going with a lower power repeater, and higher gain antenna?
one question I have is the pattern of radiation.
The way I see it, there will be a small null but not huge (most omni when all bays are placed in one direction)
when you place the bays in opposite directions, you lose gain, and the radiation pattern seems to be more
oblonged, or oval in shape.
I need to cover more of a 280 degree area mobile anyways...
I would like to thank everyone for their comments, and have made a decision, on power / antenna.
- (30 - 40 Watts with 8 Bay Dipole Antenna (11 dbd gain)
the next thing, I would like if anyone has had experience with the following equipment...
would like comments on anyone having experience in using the following:
Antenna's I am considering to use:
a.. Comprod 878-70 http://www.comprodcom.com/english/pdf/base/BaseStation2005-Full.pdf
b.. Bluewave http://www.bluewaveantenna.com/products/pdf/BSE139LH0.pdf
c.. Other suggestions are welcome
Repeater's I am considering to use:
a.. Kenwood TKR750 Rev 2 -
http://www.kenwood.com/i/products/info/pmr/tkr750_850/index.html
b.. Vertex VXR-7000 http://www.yaesu.co.uk/vertex/base/vxr7000/vxr7000_1.htm
c.. Icom apparently has one available that I have heard good comments about also.
d.. Other suggestions are welcome
e.. (looking for easy programming - great performance - SUPPORT very important to me)
Duplexer's I am cosidering:
a.. CP66-13-44 (621-90) 6 cavity, 4", 138-174 MHz http://www.comprodcom.com/
b.. CP66-113-44 (620-90) 4 cavity, 4", 138-174 MHz
c.. CP66-13-76 (621-90) 6 cavity, 7", 138-174 MHz
d.. Other suggestions are welcome - (looking for best isolation (I can not seem to find a hybrid ring type duplexer, if anyone knows of one to purchase let me know.
73's
Randy Molyneaux(VE5RJM)
Michelle Molyneaux (VE5MDM)
EchoIRLP Node 1710 & 1858
EchoLink Node 48431
ve5rjm at hotmail.com
http://parc.sasktelwebsite.net
******************************************************
As I recall - every 3 db is a doubling of power - SO:
50 watts into 11 dbd antenna - 630 watts
100 watts into 8 dbd antenna - 631 watts...
OK - they are about equal...now what about maintenance, cost of antenna,
etc. The 11db antenna would probably have a sharper pattern, and require a
larger rotator. But then there is the cost of the amp, etc.
At this point - it is probably just an economic decision, as well as a
"hassle" question - which is the least hassle to set up and maintain.....
Scott, aka KB0FHP
Well, with a 4 bay dipole, over a 8 bay dipole ( I think in chosing which antenna, I
will be going with the 8 Bay (11 dbd gain) and not going to purchase the amplifier.
the cost cancels each one out.
******************************************************
Just my guess... but the 100 watts is probably going to talk better
than it hears -- since most folks will be transmitting to the thing
with 50 watts or less. I'd vote for the better antenna.
Our local 2m repeater actually is a 100 watt GE radio -- but
we have it turned down to 50 or 60 watts, because the extra
40-50 watts really doesn't buy much.
This is exactly what I suspected.
--
Dave N0RQ
http://www.powerlinenoise.com
******************************************************
One consideration often forgotten in the dB arguement is the benefit on the RECEIVE side as well. I would rather have 100W into a 3el yagi than 1000W into a dipole in most cases. Then there is the antenna pattern noise/QRM rejection as another plus.
( I am looking for the best omni direction I can get, so when you are mobile will get into the repeater)
note: about 240 degrees require to access repeater from at least 40 miles, the null part of the antenna can be less obviously.
Arne N7KA
******************************************************
You didn't say what band the repeater would operate in? - VHF (TX: 145.250 MHz RX: 144.650 MHz)
With 145 feet of cable I would assume that the antenna would be something
less than that in height above ground? (150' 1/2" Hard Line Heliax - Antenna Height side mounted 145')
The higher gain antenna will give a little better performance on the receive
side of the repeater. But if this is going to be at VHF that size antenna
will be a handful on the tower.(commercial grade tower) It will handle it since their is only 1 other antenna
positioned right at the top.
73
Gary K4FMX
****************************************************
Reading this I'm assume that you are talking about a repeater installation -correct
and not an installation for working the repeater. I'm basing that on the
remark that the area is fairly flat over a 60 mile radius.
IF that is what you are asking then things are a bit more complicated.
what is 145' of minimum loss 1/2" coax
How high will the antenna be? -Antenna height will be 145' 1/2" hard line Heliax 150'
You also refer to 4 and 8 bay dipoles. How will they be configured?
Generally when all are mounted on one side of the tower they have a deep
null off the back. You can basically get a circular pattern by mounting half
on one side and half on the other side of the tower. If there is an area
where the null can be tolerated then of course you mount them all on the
same side.
-
The way I see it, there will be a small null but not huge (most omni when all bays are placed in one direction)
when you place the bays in opposite directions, you lose gain, and the radiation pattern seems to be more
oblonged, or oval in shape. ( I have no choice, the antenna must be side mounted- for my situation)
Sharing tower space (160')
*****************************************************
Randy:
That extra 3 dB of gain from the 8 bay dipole array works on receive, too. FWIW.
73 de
Gene Smar AD3F
****************************************************
-------------- Original message ----------------------
From: "Randy Molyneaux (ve5 rjm)" <ve5rjm at hotmail.com>
> I was curiously seeking info on a new repeater and came across many sites, and
> formulas
> and one in choosing the best overall system for the cost. What would it be.....
>
> Let's say in choosing equipment everything is fairly close in camparison.
> 50 Watts (100 % duty cycle)
> Let's not disucss options...especially right now?
> 145 feet of 1/2" coax line...(Minimum loss)
> the question is?
>
> Would you consider an amplifier pushing out 100 Watts at 100 % duty cycle over a
> 4 bay dipole antenna (8 dbd gain)
>
> or
>
> Would you consider 50 watts over a 8 bay dipole antenna (11 dbd gain)
>
> overall the area within an 60 mile radius is faily flat.
>
> All suggestions are welcome
>
>
>
> 73's
> Randy Molyneaux(VE5RJM)
> Michelle Molyneaux (VE5MDM)
> EchoIRLP Node 1710 & 1858
> EchoLink Node 48431
> ve5rjm at hotmail.com
> http://parc.sasktelwebsite.net
> _______________________________________________
>
>
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk at contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
73's
Randy Molyneaux(VE5RJM)
Michelle Molyneaux (VE5MDM)
EchoIRLP Node 1710 & 1858
EchoLink Node 48431
ve5rjm at hotmail.com
http://parc.sasktelwebsite.net
More information about the TowerTalk
mailing list