This is the Continental Equipment Section of
The Broadcast Archive

Maintained by:
Barry Mishkind - The Eclectic Engineer
Last updated 6/20/11

The Continental 317 Series

Of all the transmitters built by James Weldon and company, few achieved the status of the 317 Series of 50 kW transmitters. Sure, Continental made the super power rigs used overseas for 100 kW and up, both medium and shortwave. But the 50 kW "flamethrowers" that lit up the dial in the US, Canada and Mexico brought much domestic fame to the Dallas- based company.

There were 215 of the 317s built by 1995. Some of the 317s are still in service as Main transmitters. Many more are primary standby units.

So far as is known, the original model was designated Model 101, Serial 101- and only one was built, eventually being used at WINQ in Tampa, FL.  

The 317 series started with three sisters:

  1. WDIA in Memphis, TN

  2. CKWX in Vancouver, BC, Canada

  3. KRLA, Pasadena, CA.

And then ... there were those "B"s.... and a legend was born.

101

If you have a picture of the WINQ transmitter, please let me know.

 101 - WINQ, Tampa, FL

Essentially, this was a Western Electric 407-A1 with a Continental nameplate.
Only one was built, originally as a driver for XERA's 250 kW transmitter. However, it was replaced before serving in that use. The transmitter is said to have sat in a boxcar for 10 years before being reinstalled at WINQ in Seffner, FL around 1960.

Ron Youvan: Starting on the far left, there was a huge 480 Volt primary breaker. The next compartment had a glass door into the HV power supply area. 

Next came a 1 kW WE transmitter with four 866s on the top shelf, arranged into one RF amplifier and three audio drivers (or the other way around),  both connected to the grids of the two 10 kW amplifier grids through a "bucking bias" supply, I believe. The oscillator tubes were 807s. 

The next (to the right) compartment was the two driver tubes, the last two compartments housed the peak then carrier tubes. (or the other way around)

The three right-hand cabinets had thick glass doors; if you touched the right two (the glass) softly you would get a RF burn on your finger or hand.

Most of the ceramic piping was broken when removed from storage so it was installed using PVC tubing. The plates had 18 kV on them so the conductivity if the water was quite important.

Behind the transmitter was a pump & heat exchanger room. (and distilled water storage)

 

317 - 195x to 1959  

317 - As Continental began to build the 50 kW units in-house, the model number 317 was given to it. The original series were largely the WE 407-A1s with some cosmeticchanges. 


This is from KRLA, Pasadena. The 50 kW section was installed in 1959. (The transmitter used the WE 10 kW unit that was installed in 1941.)  For more information, check the KRLA tour page.
317B - 19
The317B was the first unit fully designed in Dallas by Continental.

This is from the brochure for the 317B when it was first introduced at the NAB show in 1958.
Continental Electronics 317B, 50 kW transmitter, Serial #1 at WJR in Detroit.

There were 12 of the 317Bs built. The last one went to Harlingen, TX.

Serial #2 of the Continental 317B Powerhouses. The 317 series set new standards for high power AM transmitters in the late 1950s.

This transmitter ran for 40 years until retired from duty as "Main" in 1999.

 
     

317C - 1966 to 

The upgrade to version 317C came came in 1966. The first unit was delivered to XETRA in Tijuana, Mexico. 59 of these were built.

This is serial number 53, installed at CBL, Hornby, ON
     

317C-1 - 1978

Version  317C-1. The first one went to KIRO (710), Seattle, WA in 1978.

This is the eighth 317C-1, from WJNT, 1180, in Pearl (Jackson), MS  (It was originally installed at CBC's CBOF in Ottawa on 1250 from 1981 to 1993.)
     

317C-2 - 1980 to 1987

This 317C-2 50 kW transmitter was considered "the one to buy" for well over a decade and a half, after its introduction in 1980.

The first unit was delivered to CFRB (1010), Toronto, Canada 

88 of these were built, the final one going to WBAL, Baltimore.
     

317C-3 - 1987 to 1997?

317C-3 - essentially a C-2 with a solid state driver. 

The first was installed at WPBD in Atlanta on 640 in 1990.

Shown: WMAQ's 317C-3, installed in 1984. Picture courtesy: Jeff Glass.
Dave Hultsman reports: "The main difference between the "2" and "3" series was] the replacement of the 4-400C RF driver tube with a solid state audio driver to feed the two 3CX-3000 Modulators. There were other smaller modifications to the the audio processing and feedback boards."

According to the factory, the change in driver "could" have meant a need for a new type notification, so they did it anyway. Otherwise, it really was a pretty close sister to the C-2
   
It was the dawning of the solid state high-power AM transmitter that sealed the fate of the 317 line. The Nautel Amfet 50 and the DX-50 from Harris virtually killed sales of the 317C-3. They were so much more efficient that the power savings practically paid for the new transmitters. Continental was going through another in its series of owners and did not fully grasp the need for a 317D solid state model - at least not well enough to design and build one. Market share plummeted, and soon Continental announced their exit from the AM transmitter line. 

The last 317C-3 was delivered to xxxx in xxxx.

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