Mike,
Although I don't have an NHRC, I've encountered this problem once before with
another system. Look at all of your capacitors, especially from power to
ground, or from audio to ground We found that one of them was leaky, and when
removed from the circuit, the hum went away.
Just a suggestion, good luck in finding the problem.
Don, KD9PT
----- Original Message -----
From: Mike DeWaele
To: Repeater-Builder@yahoogroups.com
Sent: Sunday, October 19, 2008 7:28 PM
Subject: RE: [Repeater-Builder] Ge mastr 2 link question
Paul, Eric
Thanks for the response. I did some more testing with your suggestions. I
tried hooking both radios up to a deep cycle battery. The hum is still there so
I think that rules out the astrons! The audio from the main repeater to the
link isn't as bad as from the link back to the main repeater. Both have a hum
to them however the 2 meter to the 440 you can hear the voice. the other way
all you get is the hum.
For testing I have it on the bench in the basement. the only common
connection is only the audio and tx lines between the two radios. I have also
tried it with a common ground as suggested by NHRC in the controller
directions. Both have the same results.
I want to make sure it works here before it goes back to the hill. At the
site it's just my radio equipment and Wifi internet which has not given me any
problems with both machines working there prior to bringing them to my house to
work on this linking project.
Maybe tomorrow I will give NHRC a call and see if they have run into this
problem before.
Thanks,
Mike KA2NDW
-----Original Message-----
From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] Behalf Of
Paul Plack
Sent: Sunday, October 19, 2008 4:59 PM
To: Repeater-Builder@yahoogroups.com
Subject: Re: [Repeater-Builder] Ge mastr 2 link question
Ditto the possible issue with the Astrons, but you may also have too many
common grounds.
If you have the grounds of the machines interconnected through (1) the
power supplies, (2) antenna and/or feedline bonds, (3) rack rails, (4) through
the linking cable and (5) an additional, "just to be sure" ground strap between
the radios, you could very easily have a ground loop.
Since all the interconnections are made using unbalanced audio lines, you
can't just lift the ground at one end as we might try in the pro audio world.
Sometimes, a cheapo audio transformer, like the 600-ohm isolation transformers
from Radio Shack, are enough to alleviate the loop, because they allow you to
leave an audio ground floating from the chassis at one end of the link cable.
A quick, cheap investigative tool here is one of the old
three-into-two-prong AC plug adapters. If you use it to lift the ground pin on
one of the Astrons and the problem goes away, it will be an important clue.
Good luck!
73,
Paul, AE4KR
----- Original Message -----
From: Mike DeWaele
To: Repeater-Builder
Sent: Sunday, October 19, 2008 1:30 PM
Subject: [Repeater-Builder] Ge mastr 2 link question
Hi All,
I'm having a problem linking two mastr 2 radios together. I have one site
and want to full time have my 2 meter and 440 machines linked together.
Equipment : (2) Astron R-35 power supplies (one for each machine)
(1) Duplexed GE mastr 2 mobile for 2 meter machine.
(1) duplexed Ge mastr 2 mobile for 440 machine
(1) NHRC-4/M2 controller installed in the 2 meter radio
(1) cord made up out of 2 mastr 2 cables
Both units were tuned up and working properly as independent repeaters
before attempting this project.
Then we started the linking project!
The radios are linked via the made up cord with the 2 meter machine being
the main repeater and the 440 as a slave repeater on the secondary port.
The
set up works properly on both ports in both directions. The id sounds fine
and the courtesy tones are fine. The problem is the repeat audio in both
directions has a humming noise that almost sounds like it is being over
driven. We have adjusted levels on both the controller and discrimators in
both radios to no avail.
We do have a common ground between both radios per the instructions with
the
controller. I'm thinking there is smething that needs to be padded in the
audio lines. I'm researching the web but if any one has gone before me
with
the same project I was hoping to save some time.
Thanks,
Mike KA2NDW
