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PL504

Sensibly equivalent to:
27GB5 PL500
    
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The PL504 is a purpose designed television pentode line output valve. It was introduced as a replacement for the PL500. This exhibit has the older Mullard logo and PL504 has the later stylised logo.
The peak anode voltage is quoted as 7,000 Volts and shows why the line output stage of a television receiver was the last consumer electronics product to remain a valve. The CRT excepted of course.
TV line output valves found their way into amateur radio transmitters for service at HF (up to 30 MHz) because of their peak voltage characteristics and relatively high current capability.
Looking along the grid axis. The staining in the glass is due to a hard life in a TV.
The copper control grid supports have heat radiating fins above.
The wide glass tube envelope is 28 mm in diameter, and excluding the B9D base pins, is 93 mm tall.
References: Datasheet & 1040. Type PL504 was first introduced in 1961.

 

Pin Connections
B9D
1
2
3
4
5
6
7
8
9
tc
g1
g1
k,g3
h
h
g2
g2
k,g3
k
a

 

Absolute Maximum Operating Conditions
Pentode
Vh
Ah
Va
Vs
mAa
mAs
27
0.3
75
200
440
30
Thanks to Frank Philipse for supplying the above PDF datasheet.
Updated January 28, 2019.
shape:wide.glass.tube construction:all.glass type:pentode age:1960.1975 base:b9d heater:300ma pins:9 pin:1.g1 pin:2.g1 pin:3.k.g3 pin:4.h pin:5.h pin:6.g2 pin:7.g2 pin:8.k.g3 pin:9.k pin:tc.a
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