On going into SEND with key-down,
the output power goes to its normal
level, but it soon drops almost to zero; after a second or so, it
returns to the original level for a short time before starting on
another fold-down. The rate of the fluctuation seems to depend on the
power level: faster at high powers than at low power. The ALC level
always fluctuates in sync but in the opposite direction with the output
power. These doesn't seem to be any problem at power levels under about
10 watts. In all observations of this problem, the rig is driving a
perfectly matched load (near-zero reflected power.
When I send my call (KE2S) in cw, the power usually drops on the last
dah of the K, and the E gets sent at nearly zero power. Similar power
instabilities occur in ssb and in all other modes.
The problem you are having is a
common one. There is this little DC-DC board X59-1100-00 that went out
on me twice. 1st time I had Kenwood fix it, cost me $150.00. The 2nd time it
went out, just this last December 1999, I decided to fix it myself. The board
can be order from Pacific Coast Parts and cost about $10.31. The hardest part of
the repair is getting the board unsolder off the RF board. The following is
what was sent to me by K9NX on how to repair it. I will add my notes ***:
<SNIP>
>My question is: Has anyone had
experience removing this board and installing
>a new one? It is mounted
vertically on the RF Unit board X44-3120-00. I
>would like to order the new
board and install it myself if the job is not too
>hard.
Been here done this.
What you need:
1) A really good temperature controlled,
ESD safe soldering iron set at
about 700 deg F ( 800 is too hot !)**(I
used a 30 watt soldering iron from radio shack with no problem)
2) A pair of small dikes (side
cutters, nippers, etc)
3) a good solder sucker.***I also
used solder wick from RS
What you do
1) remove the RF Unit from the rig,
As I recall there are 4 or 6 screws and
several plug in cables.
***The RF unit is on the LEFT
side of the TS-850S on top. You can identify it as it has some FM mike gain and
deviation alignment control that you will see looking at the rig on the left
side with the top and bottom covers removed. There are 3 cables that have to be
unplugged. Going left to right, the first two have connectors on them and just
unplug. The 3 cable is on the right is a flat ribbon cable that just pushes
into the connector. It pulls right out, but be very careful not to twist or
bend the cable. Once the cables are removed, there are 4 screws that hold the
board in place, remove them and slide the board out the left side. The DC-DC board
is marked with the part number, it is the last vertical board on the right side
of the RF board. Remember that the component side of the board go's to the
right.
2) Using the dikes cut the old DC-DC
converter board pins one at a time. DO
NOT ATTEMPT TO UNSOLDER IT
***** I did not have a small
enough dike to cut the pins. So I just rocked the DC-DC board back and forth
until it broke loose. Then I was able to pull the pins out, one at a time, from
the top while unsoldering from the bottom.
3) Using the iron and solder sucker
remove the stubs of the cut off pins
from the RF Unit and clear the holes
of solder
**** I used a 1/4 resistor wire
to clean out the holes.
4) In doing step three above do
every other pin/hole then come back and do
the remaining ones. This minimizes
damage caused by heat build up..
5) Stick in the new board, solder
the pins and then re-install.
**** Remember the new board
component side goes to the right. There is no alignment. Just put the RF board
back and carefully plug the cables back in.
Hope this helps, Let me know
Joe K0BX
E-mail address : [email protected]
My Homepage http://www.qsl.net/k0bx