Collins 21E Adventure

Paul K2ORC                                                                                                                       Click on thumbnails to enlarge

Chapter 7 

                  Update July 2002

To give an idea of what a CE at a small radio station has
to contend with, it was intended that this chapter contain
an interview with Don Perkins, N2IVW, Chief Engineer (CE) of WEBO-AM, Owego, NY.  In particular, the interview was to cover Don's experiences with the 21E at WEBO. Unfortunately, on the date of the interview, Don had to reschedule due to events beyond his control. Hopefully, the interview will take place in time for the next installment.

Following the appearance of Chapter 6 last month, Don sent email.  Part of his note containing corrections follows:

"I just got done reading your latest installment on the
21/E project and a couple of corrections are needed. It
appears to say WEBO ran it at only 500 Watts. That's not the case. We used it for 5kW (WEBO is licensed for 5kw Daytime). It only ran at 500W during it's Pre-Sunrise Authority time every morning except in the summer. Also  that Plate transformer is not a Dahl.


It's made by Commercial Radio Supply in Cavendish Vermont.  Finally, about the oil. Considering all I and my predecessors had  to do to keep that thing on the air, including a fire in the PA cabinet during my watch (I rewired the entire PA side after that with the guidance of veteran radio engineer Sherman Clapman) wiping up the sheen of oil at the bottom of the blower was the least of my worries."                


Hams who would like to ask Don personally about his
experiences may want to check into the Tuesday evening
Antique Wireless Association SSB net on 3.837 mHz at 8:00 pm ET (0000 UT) where Don often checks in.  In the meantime, thank you Don for keeping the article accurate. 


On reexamining the iron and the photos of them, it is clear that it was the mod transformer (all 200 pounds of it) and the mod reactor, discussed earlier and shown here with the new insulators Norm installed, that came from Dahl.









The power transformer, as may be seen, is a behemoth. It even has its own cabinet which might remind those who've lived in homes or apartments with the old time, clanking steam radiators of a small radiator cabinet.  Converting this three phase beast to single phase operation in order to prevent loss of power to the West Corners area of Endicott, not to mention FCC enforcement action, is going to make an interesting chapter once the job is underway. 

Only the final stage plate iron uses three phase power. The exciter alone is capable of 300 watts out.  At this time, Norm is planning to rewire the final amp power supply to deliver the plate voltage and plate current as if it were running low power of 500 to 750 watts.  This will take a bit of experimenting.  He will attempt either to
reconfigure the existing plate iron to single phase, if
possible, or try to barter for a single phase version.

Driving one phase of a three phase transformer would not work at close to full power output, but 500 watts power output is about 10 % of the transformer's capacity and remember, it doesn't have to be switched back and forth to full power daily.  He may use  variacs and other transformers to come up with the correct voltage/current. 

Finally, to view the results of the blower cleanup, comparethe accompanying photo of the cleaned up motor with the one that appeared earlier.

Stay tuned.

Paul ORC

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