Subject: TR-8400 channel spacing
If you live in Southern California, a change to the 440 Mhz channel spacing
from 25 Khz to 20 Khz could cause you some problems if you have an older 440 Mhz
transceiver such as the Kenwood TR-8400. This transceiver comes from the factory
with 25 Khz channel spacing and no provision for changing it - or so I thought. Since
the PLL operates with a 10 Khz reference, this should allow allow a 10 Khz channel
spacing. So I spent some time trying things to see if Kenwood might have somehow
made provision for other channel spacings. The answer is YES! A 20 Khz channel
spacing may be obtained by simply cutting a single diode.
To make the modification remove the top of the transceiver and locate the
microprocessor (42 pin IC). There are two diodes standing up at the end of the
microprocessor nearest the side of the transceiver. The diode marked D210 (closer
to pin 42) is the one to cut. Reapply power and enjoy 20 Khz channel spacing.
All other transceiver features remain unchanged.
If you want to get fancy - you may install a switch for either 20 or 25 Khz
channel spacing. This seems to work OK but you may get some strange frequencies
unless you remember to actuate the switch only when you are on an even 100 Khz
channel. Both 20 Khz and 25 Khz frequencies store in memory.
SOURCE: The QRZ Windows Ham Radio CDROM |
