This is the RCA Section of
The Broadcast Archive
Maintained by:
Barry Mishkind - The Eclectic Engineer
Last Update 5/1/08
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Radio Corporation of America Camden, NJ. |
RCA 5 kW Transmitters
From the time RCA was formed (using the combined engineering of Westinghouse, AT&T, Marconi and GE), the company was a formidable source of broadcast gear. The last 5 kW unit was shipped in 1979 or 1980. In 1985, GE bought RCA and dissolved it.
It is worth noting that most of the RCA 5 kW transmitters were versions of the 10 kW units, with a reduced tube count.
The RCA 5 kW Series:
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5A |
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5B |
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5C |
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This unit (x-KOB) is now on display at the Bolack Museum in Farmington, NM. According to the folks there, This is actually a 10C, which was used at 5 kW to provide RF drive for the 50E
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5D |
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| The modulators were class AB-1 891's; not class B. The PA 892s were driven by the 250D | |
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5DX |
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5E |
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| Essentially the same as the 5D in a newer cabinet | |
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BTA-5F (194x) |
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| Essentially a Post WW-II model, the BTA-5F
(RCA now differentiated the AM line from FM transmitters by using "BTA"
and "BTF" prefixes, respectively), benefited
from an aggressive push by RCA, including low prices and factory financing. This
made the 5F the transmitter of choice for hundreds of new and existing 5 kW
stations.
892 drivers were now used to modulate one 892 PA |
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This BTA-5F was used at WERE, Cleveland, OH. |
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Mike Callaghan remembers this transmitter fondly. He took
some pictures as the transmitter at KIIS, Los Angeles, was pulled out of service in 1975, after
25 years of faithful service - and cannot forget the quality of the
wiring.
Mike says: "When the covers came off and we saw that wiring, there was silence and disbelief. That's like 14 gauge solid copper with heavy, heavy cotton insulation. Every bend is perfect. Every wire is perfectly parallel to the one next to it. No multi-conductor cables. Everything ran separately. And the transmitter was built with union labor, in a factory where quality was the first priority. It's a sight I'll never forget." |
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A closer look - and you just have to marvel at the care and effort that went into the construction of the RCA BTA-5F |
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BTA-5G |
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BTA-5H |
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| The BTA-5H used two 807s to drive an 833A driver for the 5762 PAs (two for 5 kW, three for 10 kW) | |
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This BTA-5H was at KTOK, in Oklahoma City. |
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KOH (1951) |
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While not strictly and RCA transmitter, it is placed here as
a unique, station-built transmitter.
The first Ampliphase (or Outphase) transmitters were built by McClatchy engineers. The KFBK, Sacramento, was a 50 kW unit, the KOH, Reno, NV, unit was 5 kW. After building them units and operating them, McClatchy sold the rights to RCA. |
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BTA-5J (1962) |
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| A single cabinet Ampliphase model, a cutback from the BTA-10J The transmitter was designed differently from the 50G and 50H Ampliphases. | |
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BTA-5L (5L1) |
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| The 5L was the Ampliphase model.
It used two 8122 drivers to feed two 3CX5000H3 PAs
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This BTA-5L was removed from WKZO. |
| The BTA-10L1 used four 8122s into two 3CX10000H3s | |
| BTA-5R | |
| Two Cabinets, two 3CX-3000 modulating a pair of RCA 5762s with Cathode and plate resonators | |
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BTA-5T (1961) |
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| The BTA-5T was the BTA-5R with solid state
rectifiers.
The 4-125 driver fed the 5762 PA. A 3X3000F1 was the modulator for the new "high efficiency" PA stage, which needed only one 5762. There were several color changes in these models, Red, Dark Blue with Lite Blue doors and dark Blue cabinets & doors. Price in 1961 was $17,745 |
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BTA-5U (1964) |
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| A rework of the BTA-5T, the BTA-5U was
designed to be field convertible to 10 kW. It was three cabinets wide -
and essentially the BTA-10U with only one 5762 PA tube.
The modulators in the BTA-5U were a pair of 3X3000F1s. Price in 1964: $20,500 |
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| This is a BTA-10U, from WPFT, a functional lookalike. |
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BTA-5SS |
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The RCA BTA-5SS was a solid-state unit. The design was purchased from Westinghouse in 1978 or 1979. The last remnants of the RCA AM transmitter design group working in Pittsburgh improved it and then built and marketed it as the BTA-5SS. They used WWSW as their beta site with serial #1. WSJS got the second US-shipped unit and the third went to KALL (Salt Lake City). A PDM/PWM based design, the devices used were all high-voltage bipolar. The power supply ran about 300 Volts. Total PA voltage ran 270 Volts and collector current around 25 amps. Some reports indicate about a dozen and a half were sold. According to the story, many were bought back and replaced. |
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