JB wrote:
"Gary Smith" wrote in message
...
Hi, i have an alinco dualband radio i want to set up as a link so i can
access repeaters from the mobile as i have to travel around 100kms to
get them in the car. Here is the scenario:

1. a 70cm verticle at the top of my tower
2. 3 or 4 2m yagi's also connected pointing towards the repeaters i want
to access.
3. all these feed into a dualband alinco.
4. tx\rx on 70 from car to tower verticle
5.crossbands to selected repeater set on alinco on 2 metres.
6. repeater transmits, alinco picks it up and retransmits on 70cm to my
car.
I can change channels remotely on the alinco from my car dtmf mic. VERY
HANDY FEATURE. so i could be listening to repeater 1 and then punch in a
code then another and change the alinco at home on the tower to go to
repeater 2 etc.

It all works, but the one that is working just has a dualband verticle
attached as it can "see" all the repeaters in it's area. It's about
250km form here so totally different terrain etc and i can't access it
from here. i need yagi's because the repeaters i have access to are a
LONG way from me so i need the gain. I can currently get them with my
verticle but some are very flakey, dropping in and out all the time.


WILL THIS WORK?

IS IT POSSIBLE?

I know there would be much loss in connections etc. the rig would only
be putting out around 20w otherwise it will cook itself.

I'm guessing i would need a diplexer to combine the 2m and 70cm antennas
to the one ant socket on rig, and some power dividers for the 2m yagi's.

Get thinkin!!

Waiting for replies......

Thanks

Gary

There are power dividers available (expensive) that maintain 50 ohms at all
ports but you will probably lose 6db through that.

The Alinco will probably burn up even with both bands set to low power. The
mobile package is only capable of giving off so much heat and depends low
duty cycle. This is a problem with all mobiles as the design paradigm is for
one person transmitting 1 min on and 3 min (or more) off. When operating as
a repeater, EVERYONE TRANSMITS ALL THE TIME. There is no greater test of a
continuous duty station than a bunch of hams.

Many years ago I thought this to be do-able with a DR-600 because of the
sales brochure, and spent some time trying. One of the most aggravating
problems was the DTMF decoder falsing and having no idea what was happening
because of no telemetry. The radio would even change the control frequency
because of that, leaving me totally out of control and in complete
embarrassment.

I do have a FT-8500 in the car that acts as a "mobile extender" with my HT,
but I don't feel confident enough to be more than a 2 minute walk away from
the controls.

TX/RX on 70cm is best done with a real repeater with a remote/repeater
controller system porting to your base station radio. It is legally
required for you to be in control and you cant do that if the base is
transmitting on 70cm instead of listening. And who identifies on 70cm?

Doing this successfully entails a long and expensive learning curve. I give
you a leg up. I got started in the 70's. These days, usable repeater
controllers can be had for under $150 and old Mastr2, Micor and other
retired conventional continuous duty stations can be had for under $500.
You can even get a rotor that can be macro programmed from the controller to
turn to preset headings when channels are selected.

Get other locals to chip in and support the project.


All noted, thank's for the input.
I will have a look at some controllers.

As i mentioned, a fellow ham has one working. has had for a while. He
said they ran it at 30w and blew it up, it's now at 10 and seems to be
doing a good job. We both have DR-610 radio. as for "local" hams to chip
in, they are 100+km away from me so i would be the only one using it here.

Thanks, more to think about...

Gary