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Return to top of page · Post #: 31 · Written at 3:20:28 AM on 29 May 2010.
	Flakes Location: Adelaide, SA Member since 27 February 2010 Member #: 630 Postcount: 398
The equipment that I am planning to use with this amp and preamp has "Line Out" capabilitys. My Diskman that I use a bit with valves (Radios with PU inputs connected to the volume control) also has a "Line out". Will I have to use the Cathode follower with this type of equipment. ‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾ Valve radios, They just don't make them like they used to

Return to top of page · Post #: 32 · Written at 11:04:15 PM on 29 May 2010.
	Marcc Location: Wangaratta, VIC Member since 21 February 2009 Member #: 438 Postcount: 5389
Some of those PU's on valve radio's are cathode followers. If it has enough drive to work on the volume control. It will work with the 6SN7. but make sure that there is a capacitor blocking dc coupling. The grid leak on the 6SN7 can be replaced by a potentiometer (500K) and the pots sweeper used as the input providing the capacitor is added. Marc

Return to top of page · Post #: 33 · Written at 11:20:25 PM on 29 May 2010.
	Flakes Location: Adelaide, SA Member since 27 February 2010 Member #: 630 Postcount: 398
Cool thanks for that Marc. Just for information. I have been looking through RT&H DVD and have fount the Tuner that was used with this AMP. It is in May 1948 page 60. it is a 3 valve superhet comprising of 6K7G RF-Amp, 6A8G Converter, 6B7S Det & IF amp. The Tone and "Preamp" stage of this chassis almost directly reflect my diagram found and listed above. The only other thing that there is on that chassis, Is another valve stage. I assume that this is for a phono or mic stage. I haven’t bothered chasing it yet but it has an Un Marked valve in it. I think it might be another 6SN7. I think I will feed my "AUX" i/p to the rotary switch that selects between radio and the other unknown i/p. I will just change the switch to a 3 or 4 position one. This switch also cuts off my radio section by dropping out the HT supply to it when in the other position similar to the way that my Philips 172 set works. Oh well now to strip the whole thing down to a bare Chassis repaint and completely rebuild it again using new resistors, Caps and Wire. Should take me a couple of months!!!! ‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾ Valve radios, They just don't make them like they used to

Return to top of page · Post #: 34 · Written at 7:27:00 PM on 30 May 2010.
	Marcc Location: Wangaratta, VIC Member since 21 February 2009 Member #: 438 Postcount: 5389
It may be that they were showing coupling to the next stage? Paper work will however, sort that out. Strange that they used a 6B7, when all the others were octals? 6B7 & 6B8 are the same valve with a different base. 6A7 & 6A8 same deal. If you are rebuilding with new components, remember the warning on voltage ratings of resistors. Marc

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