{Collins} An atypical Collins tale



Friends, 

 

On 30 July I posted on this list without much hope of success a request for
a replacement T-402 low voltage transformer for my KW-1. As expected none
was found. The multi-winding transformer (800VAC/CT, 6.3 VAC/CT and two 5.0
VAC secondaries) was obviously a "special" for Collins and its use made it
likely that it was for the unique design of the KW-1 only. So the
transformer had to be pulled in a bloody operation for a trip up to Gary's
Transformer Rewind Service hospital for treatment. On removing the
transformer there was a fascination finding. There was an extra pair of
wires exiting the transformer.  There wires were deeply buried into
factory-laced multi-wire bundles and after about 4 inches just ended. Gary's
examination has concluded that these wires were from an extra unused 115VAC
primary winding.   Why did this happen?  One can speculate, but one possible
explanation is that in an early design of the KW-1 Collins had the option,
as they do for the high voltage system of feeding the primary at either
115VAC or 230VAC with the windings in series. The transformers were ordered
with the dual winding and then Collins made a decision for 115VAC only feed.
There still remains the possibility that there was another model transmitter
(commercial?) that did use the same secondaires but was designed for 230VAC
only, 

 

And here is a more surprising story.  In doing the removal work, I used the
schematics and cabling diagrams in the KW-1 manual posted on our CCA site.
I found that Figure 7-4, KW-1 Main Schematic contains two serious drawing
errors related to the low voltage supply, which if they did represent the
actual rig wiring would make then rig inoperable and cause damage.  The two
center taps of T-402 and the supply bleeder resistor are not grounded as
they should be, and incorrect wiring is shown for the filaments of the
6.3VAC tubes serviced by the supply.  Interestingly, the previous diagram
Figure 7-3 KW-1 Cabling Diagram has the correct wiring for both of these
issues.  The error in Figure 7-4 is clearly a drafting error that was not
caught before publication of the manual.  I wonder if the draftsman and his
checker were fired or at least reprimanded when the error eventually came to
light as it must have. 

 

Two interesting stories that we can only speculate about unless someone on
this list has more definitive information.

 

73,

 

Buzz

W3EMD





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