Tube substitutes for RA17C12 North American Version

The North American model RA17C12 has different tubes and various changes to component values when compared to the RA17L. The basic architecture remains the same. There are 22 tubes of 9 types -

• 8 6AU6 high slope RF pentodes, V1, V2, V5, V6, V8, V10, V12, V19,
• 4 6BA6 vari-mu RF pentodes, V14 - V17,
• 2 6AL5 dual diodes, V18, V21,
• 1 6AS6 dual control pentode, V4,
• 2 6688 RF pentodes, B9A base, V7, V9,
• 2 6BE6 heptodes, V11, V13,
• 1 6ES8 dual triode, V3,
• 1 12AT7 dual triode, B9A base, V23,
• 1 6AQ5 power pentode, V22.

There is no V20 or V24.
The audio output stage is a considerable inprovement over the British version. It uses a 'real' output pentode and a double triode, instead of the gross abuse of an RF pentode as the output stage which is the British version. Audio quality is still not great if the tiny (tinny) built-in speaker is used.

WARNING

There are two distinct series of RA17 receivers, the British Military versions, which uses CV numbered tubes and the North American versions, which uses U.S. commercial tubes. The tube sets for these different series are not identical. Several tubes, while similar in function, have a different pin-out. Inserting the tube from the other set could result in thedestruction of the tube and might cause damage to other components.  In particular, many substitution guides give 6AS6 or its variants as equivalents for the S6F33 (special 6F33). In fact the connections to G2 and G3 are reversed and the connections to the base must be changed to do this substitution.
Where CV numbered equivalents are shown for U.S. tubes below, they may be safely substituted.

Tube Equivalents

Complement	Type	Racal Original Equipment	CV equivalents	Pro-Electron	Industrial	Mullard	Other Manufs
8	High slope RF pentode	6AU6 6AU6W* 6AU6WB*	CV2524	EF94	6136*	_	_
2	Dual diode	6AL5 6AL5W*	CV283	EB91	6058* 5726	M8079*	_
4	Vari-mu RF pentode	6BA6	CV454	EF93	6660 7496	_	_
1	Dual control pentode	6AS6 6AS6W*	CV2622 CV4011*	_	5725	M8196*	_
2	RF pentode	6688*	CV3998	E180F*	6688	_	5A/170K  EF861
2	Heptode frequency changer	6BE6 6BE6W*	CV453 CV4012*	EK90	5750*	_	_
1	Dual triode	6ES8	CV5331	ECC189	_	_	_
1	Output Pentode	6AQ5 6AQ5W*	CV453 CV4019*	EL90	6005 6095 6609	M8245*	_
1	Dual Triode	12AT7 12AT7WA*	CV455 CV4024*	ECC81	6060	M8162*	_

* this is a special quality type


Andy Cowley 2002