ARS NB9M

Swan Twins: 600-T, 600-R Custom, 600-S


The Radio Shack 0 Comments 12/21/2018 

From the Estate of AA5T

Posted By: Bradley Stone (UncleBrad)

These excellent examples of the Swan Twins are from the estate of John Thuren, AA5T of Houston, Texas.  John had checked in to the 20M Swan net with these very desirable "big Swans" until a few years ago. 

AA5T (SK) Previous Owner

A big thanks to Eddie, NU5K, who handled John's estate and placed these on EBay.  He packed them well, knowing they are indeed an important find.  Also thanks to Jeff, WA8SAJ, who has written at least one article on the twins for Electric Radio, and - outside K4BOV - probably knows more about them than anyone else on the planet.

There were only 600 of the transmitters made, and 450 of the receivers, making these units extremely hard to procure.  Of the 450 600-R receivers produced, it appears to be unknown how many were the Custom (with the 16-pole crystal filter, factory AM filter and audio filter circuitry).  Surviving R600 Customs typically have missing or inoperative AM filters.

After providing the serial numbers of the units to Stu, K4BOV, he responded with some interesting information:

600R Custom #1802 built in May 1972 2nd series

600T #1909 Built in August 1971 2nd series

600S #1802 Built in May 1972 

I confirmed with Jeff, WA8SAJ, that the receiver has the hard-to-find original factory AM filter.  This particular set is in fine cosmetic and operating condition.  Some minor cleaning and detailing was all that was needed to get them back on the air.  Even the audio filter, which uses an impossible-to-find early integrated circuit, works well.  The twins have a high-quality feel to them, and are noticeably larger than the transceivers we're all so familiar with.  The receiver is surprisingly good.  The VFOs are very, very stable and smooth as silk.  These VFOs are set up in 2KC spreads.  To go above and below the default (0) segment, the operator must set the small scale to the left, using the calibrator.  This, plus the color-coded bands, which are very different than the typical Swan transceiver configuration and take some getting used to. 

The 600-T uses 6KD6 sweep tubes, which peak around 400W in my example.  The tuneup is similar to the transceivers, but peaks are also displayed on a very cool flourescent tuning eye.  Only a touchup of the idling current was needed to get it on the air.

Stu provides more information on the Swan Twins:

Swan completed the parts list for the Swan Twins in late 1969 and accumulated enough components and manufacturing set-ups to start building 100 sets - that is, 100 receivers and 100 transmitters. The first receiver and transmitter received serial number "1". Then the following went from 0101 thru 0199 for 600R receivers and 1201 thru 1299 for the 600T transmitters These are referred to as "run" or "series" one. 

Sales of the 600R was not as robust as the 600T. Remember back in the late 1960's and early 1970's many hams already had good receivers. There were 300 of the 2nd run with the receivers being numbered 1601 thru 1899 and the transmitters numbered 1901 thru 2199. However the 2nd run of receivers was delayed due to the reason above, sales of the 600T outpaced the 600R. This resulted in only 50 final receivers being built while another 200 600T's were produced - both of the final runs were given 5 digit serial numbers beginning with 18, 19 or 20. 

There were small variations among the 3 runs of the 600T and only two from the first to the last 600R (or 3 if you consider the difference between the standard and custom). 

The first run of 600T's had two screw-driver adjustable auxiliary load controls mounted on the rear chassis behind the PA compartment for accommodating low frequency antenna matching such as on 80 & 40 meter. Further factory testing and user feedback showed these extra capacitors were not necessary; so, were dropped on the 2nd series. However, the two access holes remained. Conversely, in the final run, there were no holes drilled.

Of interest, while looking up those numbers I saw that Herb Johnson's personal 600T was #1906 and a note that his widow Mimi had the unit for sale in 2000 a few months after he passed away.

Bob, W9RAN also has a set of these twins.  Stu provided some info on his:

600R Custom #1724 built in January 1972 2nd series(right after the plant reopened following the Christmas Holiday) 

600T #1912 built in August 1971 2nd series.

The pictures shown were taken prior to a careful cleanup.  I made no attempt to paint the cases, and took extreme care when cleaning the switches and pots.  Of course, finding replacement parts for these units can be extremely difficult or impossible.

My "new" twins now occupy the coveted Studio A, Row 1 position formally occupied by the Heathkit SB-104A lineup.

You can find a lot of information about these beautiful Swans in the 1972 Swan Catalog.


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