Hi guys,
Trying to troubleshoot a KSB2 no Tx problem. I have exchanged a couple of ideas
- suggestions with Don W3FPR and Garry AB7MY, but so far have not been able to
find the culprit. I was wondering maybe someone else in the forum might have
had a similar issue and or any suggestions ?
After receiving and installing the missing NE602 IC from my KSB2 module, I have
the following problem with it:First, the initial testing and alignment of the
SSB board went ok, as mentioned in pages 15-20 of the KSB2 manual. The BFO, OP1
filters and CAr ballance adjustment went fine, but there is no Tx signal output
after trying to talk into a properly configured Kenwood MC-50 dynamic mic. The
radio seems to go into the Tx mode after pressing the PTT, but no signal at any
power level when talking to the mic. Before starting chasing the AF mic signal
around with my oscilloscope, I did verify the correct placement of ICs, diodes,
Caps etc on the KSB2 board, and did verify the presence of the correct voltages
during SSB and CW Rx on the suggested per the manual page 23 diodes D9-D13. The
voltages check of the ICs though, with the exception of U5, are mostly off the
suggested values per the manual for all the remaining ICs, with the following
most important differences: measured (Rx/Tx) suggested per
manual (Rx/Tx)U1-3 4,8/4.8 2.3/2.3U1-16
6.0/3.05 6.0/5.4 U1-17 6.0/4.1
6.0/5.6U1-21 5.8/0.06 5.8/0.1U1-28
5.6/5.4 5.6/2.4 U2-1 6.0/4.1
6.0/5.6U2-5 2.5/2.5 0.6/0.6U2-8
6.0/3.1 6.0/5.4 U3-2 1.9/2.8
2.5/2.5U3-3 2.9/3.8 2.3/2.3U3-4
2.9/3.8 1.7/1.7U3-5 4.4/4.4
0.4/0.4U3-7 4.8/4.8 2.2/2.2
U4-2 4.8/4.8 2.2/2.2U4-3 2.5/2.5
0.6/0.6U4-5 4.8/4.8
2.2/2.2U4-6 5.5/0 5.1/0 Also another
strange behavior is that when trying to activate the VOX option, SPCH 0.2 comes
temporarily on the screen, but then the K2 does not return to receive mode, and
I can not cycle through the other delay VOX options. (It seems to be frozen in
Tx, while the L or u (sb) indicator is normally flashing besides the frequency
display, as it should. In order to return to receive, I have to turn the K2 off
and then back on. Once, while having the mic disconnected, I could manage to
have VOX activated properly (the K2 going back to Rx and being able to cycle
through the VOX delay options) but it does not happen anymore..Based on the
above measurements, I tend to believe that the U1 IC controller maybe is
faulty????, even though I did observe proper antistatic handling precautions
for its installation as I did for all the rest ICs. The rest of the K2,
including the 100w PA seems to work ok when Txing in the TUNE mode, or Rx ing
in all modes.
73 to all,
Marinos, sv9dru/ki4gin
_________________________________________________________________
You live life online. So we put Windows on the web.
http://clk.atdmt.com/MRT/go/127032869/direct/01/_______________________________________________
Elecraft mailing list
Post to: Elecraft@mailman.qth.net
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com
