Re: {Collins} An atypical Collins tale

----- Original Message ----- From: "James Beitchman" <jbeitchman@xxxxxxxxxxxxxx>
To: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
Cc: "Collins@xxxxxxxxxxxxx" <collins@xxxxxxxxxxxxx>
Sent: Saturday, August 17, 2013 7:30 AM
Subject: {Collins} An atypical Collins tale


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

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.




I looked at the KW-1 schematic. While it seems possible to run it on a 115 volt line the current would be very high so I think it was intended mostly for 220 volts. The low voltage supply seems to be run from half the 220 supply but perhaps there was once some intention of having it connected across the 220 rather than across only half the line. I may have mis-read the schematic and installation instructions.

Richard Knoppow
Los Angeles

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