If you want to use the battery to isolate you from the input voltage
variations, try connecting the repeater directly to the battery and use a diode
from your power supply to the battery. I think Eric was mentioning a diode
scheme he uses just the other day.
I have operated several repeaters directly from a battery with a standard
battery charger connected to the battery to supply the charge. An interesting
side effect was that the power meter stopped turning. Apparently the very
short conduction angle at the peaks of the sine wave from the charger does not
last long enough for the meter disk to get moving.
I prefer using a battery charger to using a power supply so that a completely
discharged battery can be recharged by the battery charger where a power supply
may fold back and require some intervention to get it going again. If you use
this method, be careful to connect the charger directly to the battery and
power the repeater directly from the battery. Do not allow any common path
between the charger and the repeater or you will see some EMI due to having a
common current path. The peak current from the charger can be quite high since
the conduction angle is very low.
I use a battery with wing nut terminals as well as the standard battery posts.
Clamp the charger to the posts and power the repeater from the wing nuts.
73 - Jim W5ZIT
--- On Mon, 8/4/08, Mike Besemer (WM4B) <[EMAIL PROTECTED]> wrote:
From: Mike Besemer (WM4B) <[EMAIL PROTECTED]>
Subject: [Repeater-Builder] KRP-5000 Squelch Thumping/Scratching Intermittently
To: Repeater-Builder@yahoogroups.com
Date: Monday, August 4, 2008, 5:30 PM
Greetings all,
My club has an Advanced Communication Systems (ACS) KRP-5000 repeater (this is
the same MR-4 receiver used in the Kendecom Mark 4) with a strange intermittent
problem. Several times a day, we get a signal that sounds like a scratching
noise or a thumping sound (It’s hard to describe… I need to make a recording of
it… if I can ever catch it). It starts off as a slow scratching (or thumping
or clicking) and gradually gets faster and faster and then it fades back down
to nothing and the signal drops.
For the past year or so, we’ve just put up with it because it was intermittent
and I assumed it was external interference coming from another transmitter.
(Although we are the only one on the water tower, there is a Water Department
telemetry transmitter on-site.) My thought process changed on Saturday when I
was doing some extended maintenance at the site and had the repeater pretty
much disconnected from the outside world (transmitter on a dummy load,
transmitter switch off, receive antenna disconnected at the repeater) and the
dang thing started doing its ‘thing’. I turned the transmitter switch back on
and that had no impact on the noise, and the squelch control had no impact
either. So, now I’m convinced that the issue is in the receiver (or power
supply feeding it).
Most of the processing in the MR4 takes place in U1… including the development
of the COS signal. Since this problem can start on its own (without the
transmitter already being on) and it captures the COS, I assume that the
problem is in the general vicinity of (or before) U1. This is also the area of
the circuit where the fast squelch/slow squelch is developed.
Has anyone seen issues like this in repeaters that use the MR4 receiver
(KRP-5000/Mark 4, etc.)? Any ideas?
One thing that was mentioned to me today by a fellow who does repeater-type
stuff professionally is that he’s seem odd squelch problems caused by power
sags. I did notice Saturday that when one of the pumps kicked on at the tower,
the lights dimmed noticeably for 2 or 3 seconds. Because I wasn’t paying
attention to it at the time, I can’t confirm or deny that the problem
correlates with the voltage dip, but it seems like a good place to start.
We’re not running any power conditioning on the line now, and I don’t really
want to go to a full-blown UPS because we’ve got a good, reliable battery
backup system already installed. Any thoughts on power conditioning without
going to a UPS?
Admittedly, on my ‘to-do’ list, this is priority 23, but it’d sure be good to
have a starting place if this issue ever gets to be more of a problem, or if it
happens to show up again when I’m at the site.
Thanks to all es 73,
Mike
WM4B
146.85 – Warner Robins, GA
145.11 – Cochran, GA
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