In article .com,
KA1IOR wrote:
My Kenwood TM-221 has a problem with the intensity of its PL tone
output level. Mine is too loud, generating frequent reports of "hum"
from others.
I have the original manual with schematic and block diagrams, but no
obvious information indicates where the output tone is generated or
adjusted.
Not being wizardly and knowing there are wizards hanging around here,
I'd like to know what pot needs adjustment to settle it down to the
right level, if one exists. Anyone?
The TM-211 service manual can be downloaded from
www.mods.dk - it has
the schematic and the procedures.
As I understand it, this mobile's tone generator is on a separate,
optional plug-in board, designated TU-3A. The board has a set of DIP
switches (which set the transmitted tone) and a small potentiometer.
It looks to me as if the TU-3A tone board plugs onto the "B unit" PC
board, which is on the bottom side of the transceiver.
The alignment instructions say to adjust VR1 so that the transmitted
signal deviation level (tone, but no other audio) is around .65 kHz
(650 Hz). This is consistent with recommendations I've read for other
radios and seems to be good practice.
Bonus question: I have the same problem with an Alinco DR-590; if you
can help me with that too, that would be nice.
I've been told that in at least some Alinco radios, the CTCSS tone
level is set by a fixed resistor on the PC board (it's not intended to
be adjustable via a pot), and that it's set too high.
--
Dave Platt AE6EO
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http://www.radagast.org/jade-warrior
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