{Collins} KWS-1, Up & Running----700 Watts+ Output on 75 Meters

["Chuck Curran" <ccurran@xxxxxxxxx>]

Hello the Group:

 

I bought my KWS-1 serial number 700 almost one year ago.  Many distractions
interfered with the rapid restoration I had originally envisioned.  I had
several occasions where I asked for support from the group and every time I
received many valuable suggestions & hints.  I want to let the group know
that now the KWS-1 is running fine, with 704 watts output on 75 meters.

 

I must admit I made a mistake or two during the restoration process.  I will
condense the following comments, to avoid too much embarrassment!  

 

My latest posting was about no PTO output.  I thought I had no PTO signal.
That was my own error, the PTO was working perfectly.  

 

So, what is next?  I had not enough drive to show grid current on the
finals, so I decided to perform the initial alignment steps per the manual,
all focusing on the 80 meter band.  

 

I have some decent equipment to perform this activity, consisting of a brand
new Rigol 1102E 100 MHz scope, a HP 410B RF Voltmeter, and some Fluke DVM's.
I have the standard VTVM's all collecting dust but ready work as required!

 

I soon discovered I had no significant drive arriving at the grids of the
6CL6 drivers.  I simply plugged a BNC cable into the grid jack and measured
what was present using the scope.  OK, so I followed the manual, step by
step and produced a dramatic change when I was dealing with L201, part of
the alignment steps associated with the 1st mixer, V201 a 12AT7.  Now as you
read this, keep in mind I had 608 watts output, for 3-4 days then it
disappeared.  I adjusted L201 and the grid current went up dramatically, so
at this point I have enough drive to share with others!  I originally NEVER
saw grid current on the 4CX250B's.  I believe the issue was present when I
purchased the radio.  How I saw 608 watts on the wattmeter will remain a
point for future discussion, not sure what happened to allow that anomaly!

 

I set up this afternoon, turned on the 75A-4 and KWS-1 and let them warm up.
Everything was ready to test.  I found the 75 meter group I was hoping to
visit with, then zero beated the KWS-1 against the 75A-4.  Tuned up off
frequency and all went well.  Achieved 704 watts output, on my LP-100A
wattmeter.  I checked into the gathering, but the group did mention they
could hear a hum on the mike, when I stopped talking.  Was seeing 692-704+
watts output the entire time.

 

Another interesting item, was the date coding I found.  Please review the
Care and Feeding article, that has been so helpful to all of us.  There is a
reference to serial numbers and when a particular KWS-1 was manufactured.
The chart suggests that my rig, serial number 700, would have been built
during the summer of 1956.  I feel that is very accurate, since I have a
dead 20 meter 11.00 MHz crystal.  Today I ordered a replacement, but first
pulled the original crystal out and made sure the lead diameter matched what
I was ordering.  On the bottom of the dead crystal in red ink was stamped
"5-56".

 

That date code seems to match very well with the data available in the Care
and Feeding document!  Thank You Bill Carns!!

 

I owe a big Thank You to the many individuals who offered support and their
knowledge on a regular basis.  That plus my own persistence allowed me to be
successful in getting this 1956 jewel back on the air.  Another Thanks to my
friend who sold me a group of six 4CX250B's for $5 each, all good.  Um, I
will report on that topic by Christmas!

 

Now to track down that microphone hum-----

 

Best Regards to All,

 

Chuck Curran  W9KR

Cedarburg, WI