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VT90 (REL1, 710A, 8011, CV1090; 10E/97B see pictures further down) - the original 'micropup'


Size The valve measures 115x38mm overall, plus the filament leads.


Filament volts 8.25V
Filament current 7A
Max anode volts 9kV
Total emission 5A
Max anode dissipation 100W
Amplification factor
(Va=1kV, Ia=100mA)
Max frequency 300MHz
Peak pulse output (per pair) 10kW
Cag 3.75pF
Cgf 2.20pF
Caf 0.90pF

In this valve, the grid connection is at the top, filament at the bottom, and the anode is the centre block. The anode itself is a cylinder with fins attached for cooling. It has a thoriated tungsten filament consisting of a single helix.

In operation the valve must be mounted vertically. Forced air cooling is needed and the temperature of the anode block must not exceed 140C.

See also other micropups.


This version is marked as REL1

REL1 label
REL1 label
Markings on the anode block are: REL#1 MFD BY N.E.Co and SERIAL NO. 41692

REL1 boxREL1 in box

REL1 (VT90)

WE 710A version, serial number C (G?) 7866, made by National Union. The valve carries the number 693 on the glass.

710A label 710A label


RCA 8011, also marked VT90 and 10E/97B

8011 label 1 8011 label 2


National Union 8011

8011 label


This valve is marked CV1090 on the glass and REL1 on the anode.

CV1090 donated by Chris Colebrook

This file was last modified 14:37:58, Friday March 17, 2017

  FOR SALE: Note that any valve which is not CV marked is now for sale. Contact me via email - see the home page.