This is the Hot Glass Archive Section of
The Broadcast Archive
Maintained by:
Barry Mishkind - The Eclectic Engineer
Last Update 5/14/25
To a veteran broadcast engineer, there is nothing quite like
the glow of the glass tubes in a transmitter. The Modulator and Power Amplifier
tubes are among many things missing in solid-state transmitters, however, even
they had morphed into ceramic tubes at higher powers.
Still, the pulsing glow of the Modulators and the warm bright
PA's of a well operating transmitter ... well, it really doesn't get any better.
Here is a sampling of the Hot Glass from the Tube Era of
broadcasting:
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Tube
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Some of the transmitters that used these tubes.
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3-500Z
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Collins 828D-1, Continental 314R-1
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4-125A |
(aka 4D21) Collins 300J
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4-250A
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Collins 550A-1
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4-400A
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Collins 20V series
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4-500A
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McMartin BK-1000
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4CX3000A
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Gates Vanguard
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5-500A
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Collins 820D-1 and 820D-2
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450TH
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810
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Collins 300G, Raytheon RA250,Gates BC250GY, RCA BTA-250K and L,
BTA-1L, etv. |
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813 |
BC250GY |
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833A
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Gates BC-1T, BC-1G, BC-1H, BC-1J, Collins 20T, RCA BTA-1M
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Tube
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Some of the transmitters that used these tubes.
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3CX2500
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3CX3000
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3CX5000
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4-1000A
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McMartin BK-2500, BK-5000
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4CX5000A
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(aka 8170)
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4CX10000A
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4CX15000A
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(aka 8281)
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5762
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891R
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892R
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Most non-Western Electric transmitters. This RCA tube had very brittle
filaments, according to Bob Groome
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DX-516
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Longer life than the 892s?
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Tube
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Some of the transmitters that used these tubes.
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3CX10000
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4CX5000A
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4CX15000
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5762
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891R
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892R
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Most non-Western Electric transmitters. This RCA tube had very brittle
filaments, according to Bob Groome.
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Tube
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Some of the transmitters that used these tubes.
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4CX3500A
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5671
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1947 - RCA 50G - it made this to replace the 9C22.
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6696
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6697
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862 |
RCA Tube |
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893R
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RCA Tube
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893AR
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KEX, Portland used this one
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898
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RCA 50C 50D (this is essentially an 862 with filaments modified
for three phase heating).
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9C22
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Used in the original BTA-50F, replaced in
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WL5891
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Westinghouse 50HG-1, GE BT-25, Gates BC-50B and BC-50C
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UV207
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GE (WGY)
Stan Adams says: "Parasitics would often cause overheating and
would blow the grid low value resistors and the plate caps. It did not
like operating at certain voltages."
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UV 862
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RCA 50B, 50C (RCA's version of the GL-862A)
water cooled
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UV 863
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GL-862A
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early GE transmitters
water cooled.
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Tube
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Some of the transmitters that used these tubes.
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320A
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Used by J.O. Weldon for some of the borderblasters
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GL-862A
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WLW's 500 kW
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