Hey Scott.
Thanks for writing back. You did some work for me not too long ago. I
sent up a spectra-tac receiver that you retuned for me while Kevin was
busy somewhere. We swapped the vibrasponder tone element too. I needed
131.8, and you took what was in it and put that one back in.. Remember?
Anyhoo... I got this unit about a year ago, and it looked brand new..
Not a scratch on it. Still had that new smell too. I employed it as a
IRLP link radio. It's a 10w unit. I'd often try to operate the IRLP node
and it would not respond. Turned out to be this unit's receiver.
I opened it up last nite. Looked totally virgin inside. I cleaned the
connectors where the boards(top and bottom) attach to the chassis. I
had to take the lid off what I'm assuming is the VCO compartment to get
at a couple of screws to lift the board. It's the shiny lid that presses
down over a couple of sections inside the radio, correct?
I'll open it up again this evening and take a measurement at the test
point you indicated. I'll assume I don't need a signal present to make
this measurement. Might be good if you could give me a pointer to
location of the RX VCO coil too, so I can tweak if it's out of spec..
Is it labeled? What voltage would be considered acceptable? 7 +- 2v
or so???
It really doesn't seem temperature related. The unit operates in a
climate controlled room. I may send it up to you for a look if I can't
make any headway, if you work on these...
73s, and thanks again for writing back.
Russ
From: Scott Zimmerman [mailto:[EMAIL PROTECTED]
Sent: Wednesday, October 03, 2007 2:26 PM
To: Repeater-Builder@yahoogroups.com
Subject: Re: [Repeater-Builder] Help with Motorola Radius M120 -
Intermittent Recieve
Russ,
If the receive is intermittent, your problem is likely NOT the LO being
off-frequency. An LO that was off would rear its head as sounding off
frequency or poor sensitivity. I have had some problems with the LO
crystals
drifting as of late, but I don't think that is your problem from the
description you provided. At any rate, the second LO crystal frequency
is
44.645 NOT 45.645. The IF frequency is 45.10, so 45.100 - 44.645 =
455KHz.
It sounds to me like you might have a broken/cracked solder joint
somewhere
inside the radio or that the Rx VCO is going out of lock.
Does it seem to be temperature related? If so, that would lead more
toward
the VCO. You can open the radio and VCO compartment and see what the
voltage
is on the test point marked SL. It should be around 7v or so. If not,
you
can adjust the Rx VCO coil to get it more in-line where it needs to be.
Good luck,
Scott
Scott Zimmerman
Amateur Radio Call N3XCC
612 Barnett Rd
Boswell, PA 15531
- Original Message -
From: russcrisp [EMAIL PROTECTED] mailto:rcrisp%40gmail.com
To: Repeater-Builder@yahoogroups.com
mailto:Repeater-Builder%40yahoogroups.com
Sent: Wednesday, October 03, 2007 1:44 PM
Subject: [Repeater-Builder] Help with Motorola Radius M120 -
Intermittent
Recieve
I have a Moto M120 UHF that has intermittent receive. Doesn't work more
than it does.. A friend suggested that I count the Second LO, and make
sure it's at 45.645 Mhz. I have no service documentation on this
model,
so rather than poke all around looking for something that may not be
there, I thought I ask the group here for assistance.
Does anyone have experience with the M120? Is this indeed the correct
setting for the second LO for a UHF radio? 438-470.. Where is the
proper place to attach a counter to measure this?
Any help would be greatly appreciated. This radio is used in a link.
Best regards,
Russ Crisp
K4RCC
Yahoo! Groups Links
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