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315/316 - 1941 |
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| KRLA used their 10 kW unit for about 18 years before it became the driver for the linear amp which brought them to 50 kW - and formed the third 317 model.. |  |
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Dave Hultsman recalls:
The original 316 10 kW transmitter (a three cabinet
transmitter) was the driver for the 317 50 kW at driver at KRLA and WDIA and
CKWX.
This was essentially part of the Western Electric line after CE bought the Western Electric AM product line. I understood that CE also sold some of the 316's as 10 kW's opnly in the US, Canaga and worldwide. Robert Meuser notes: "A number went to the military. We had them in Germany (glass doors) along with 314's (1KW)..."
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315/316B - 19xx |
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The 316B had three 4CX5000A tetrodes in
parallel, screen modulated by 4 each 4-65A tubes in the screen circuit.
The 315B used only two tubes.
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| Robert Meuser: "A very deadly TX" | |
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315/316C - 19xx |
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Dave Hultsman recalls:
The 316C had two 4CX10,000
tubes in parallel operated in linear mode, screen modulated by three
4CX250B tubes. (The 315 only used one PA tube.)
I remember there was one at WCFL and one at WLAC backing up their 317C's. I know of several of the 315C's, Boston MA, WRR, Dallas, WMAK, Nashville. Robert Meuser: "I believe they called the modulation scheme 'regulinear.'" |
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315/316F - 1971 |
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A 316F |
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Dave Hultsman recalls:
"Finally, something that Sainton was
working on in 1968 when I was looking at transmitters for KLIF's new 12
tower array. They had a working prototype 10 kW two-tube solid state
transmitter.
"They finally got it out about 1971 as the 315F and 316F, using two 4CX10000's in the 5 kW and two 4CX15000's in the 10 kW. The tubes operated in a Doherty amplifier making it more efficient than running in linear fashion as the two previous models. The also set it up so you essentially peaked the grids and dipped the plates which was the way most class C plate modulated rigs tuned. "These two transmitters were the FIRST two-tube 5 and 10 kW AM transmitters and predated the MW-5 from Gates and by several more years the MW-10 from Harris." Robert Meuser: "The 316F was the goal post Harris used for development of the DX line - especially the 50 kHz audio response [and] excellent square wave performance that came with that. "The problem with the 316F was the trade off between positive modulation and distortion performance. When you got near 125% positive the peak tube started to shift from AB1 to AB2 causing a large drop in drive impedance and thus requiring much more power from the exciter. You can see the positive peak on a scope flatten out on the exciter output. " I have seen a few 316Fs modified to have a 250 W SS TX as a replacement for the original 50W exciter to solve this problem. I know of one that took the sample TX output of a Motorola AM stereo exciter, applied a 500 W SS Linear and then drove the 4CX15000s. Fantastic stereo AND great positives. I also know of one and only one unit (un modified) that had nearly 50 db stereo separation, less than 1% distortion and could just barely make it past 125% mod, all at the same time."
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