Kenwood TKM-707
Sir,
I note that your last application notes still downplay the Kenwood Marine SSB
for digital service. I have used my Kenwood TKM-707 with a PTC IIe TNC
quite successfully for Pactor-II digital service on Winlink for the past 4
mos. You do have to use the mic plug as there is no accessory plug, and the
input signal has to be attenuated to prevent overdriving. The mic plug is
Radio Shack 274-025; connect pin 2 (mic) to pin 3 of the TNC 8-pin DIN plug(
PTT); pin 6 (mic) to pin 4 (DIN) (Rx audio); pin 1 (mic) to 1 (DIN)( TX
audio), with a 47 K ohm resistor in line; pins 7,8 (mic) to 2 (DIN) (Gnd).
Solder a 2.2K resistor across pins 1 and 7,8 of the mic plug to complete the
attenuator. Use ferrite chokes on both ends of all cables. I set the FSKA and
PSKA to 500mv each; set the Tx delay to 40 milliseconds, as the Tx-Rx
switching speed on this radio is about 30 milliseconds. I normally use medium
power (50 watts), but have used 150 watts and have had the cooling fan come
on only twice in the 4 mos.
I am very grateful to George Fenwick, WB2AEF, for supplying the info on the
attenuator circuit.
Sincerely,
Charles F. Hobbs
Additional note from SailMail sysop:
One problem that we have heard about regarding Kenwood TKM-707 radios is the TR time is too long. Unfortunately, this cannot be provided for by any adjustments on the vessel. The only effect it has, however, is that it may prevent you from connecting to a SailMail station if you are too CLOSE to the SailMail station. The easy work-around is to simply connect to an alternative SailMail station that is farther away. This problem vanishes once you are farther than 700-800 miles from the SailMail station that you are trying to connect to.