Media Share 9/MEDIASHARE_09.ISO/hamradio/kenwood1.zip/TS430.FIX

Text File | 1980-01-01 | 2KB | 36 lines

Our 9 year-old TS-430S was beginning to show intermittent trouble signs.  At
times, on initial turn-on the display would take awhile before all digits lit.
Power output would drop and could be restored by wiggling various wires and
tapping various points on the RF deck or the IF board, none of which seemed
to be the same location each time.

Finally the day came when it died.  The display would only show the last digit
and a slight whining noise came from the speaker.

Voltage measurements revealed the +5 volt regulator output on the IF board to
be reading 2.3 volts.  A scope on the output showed an AC signal which in-
dicated the regulator was oscillating.  The 1 uF cap on the +5 volt regulator
input was replaced.  This restored normal operation and all the intermittent
problems went away.

VE3KYZ reported he had a problem with his '430 that was cleared when he
eventually traced the cause to an oscillation in the +5 volt regulator.  In
his case, the symptom was high level noise on a couple of the HF bands.
Varying power ouput was found to be due to the ouside trace on the RF board
which carried the final bias, expanding with temperature changes and shorting
to ground.  A piece of tape cleared this problem.

KB5CDX recently reported his '430 would "die" after a few hours from turn-on.
This problem was cleared when he replaced the +5 volt regulator.

KD7EV advises intermittent power output problems on his '430 was cured by
installing a more conventional nut on the rear panel UHF style antenna
connector.  Apparently a faulty ground connection at this point caused a change
in the VSWR which affected the sensing circuit and thus reducing the RF output
power.

It's hoped the sharing of these experiences will benefit others observing
similar problems with their TS-430S.

73 de Jack, [e-mail]