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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 later Mullard logo and PL504 has the older style of 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.
Each of the supports for the control grid has a U shaped heat sink fin on top.
Visible at the base of the anode is the bright metal of the beam plates.
The wide glass tube envelope is 28 mm in diameter, and excluding the B9D base pins, is 93 mm tall.
References: Data-sheet & 1040. Type PL504 was first introduced in 1961. See also 1961 adverts.

 

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.
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