The most suitable valve for an anode-bend detector - UK Vintage Radio Repair and Restoration Discussion Forum

Neil Purling · 19th Dec 2013, 8:59 pm

I am just wondering if there is any characteristic that is particularly desirable.
I have got a number of EF91 & I need some use for them!
I have got coils & I have previously used Octal EF39 & 6K7 as RF amplifier & detector I was thinking of re-visiting this type of TRF that is the type used in the legion of kit radios, but updated slightly

G6Tanuki · 19th Dec 2013, 9:16 pm

Is it a regenerative detector? I've generally found that non-variable-mu pentodes are best in such duty, though low-slope variable-mu pentodes [such as the 1T4/1S5 battery valves] are OK in such applications.

An EF50 works well as an "infinite impedance" detector.

FERNSEH · 19th Dec 2013, 10:17 pm

In my simple superhet project I chose a high slope pentode for the anode bend detector. At present I'm using a Mazda 10F1 because an UF80 was not to hand. Other valves such as the EF50, EF80, EF91 and 6F1 work equally well. Octal fans could consider the 6AC7/1852.
The circuit of my superhet is here: http://vintage-radio.net/forum/showt...=101388&page=3
Post No. 48.

DFWB.

19th Dec 2013, 8:59 pm	#1
Neil Purling Nonode Join Date: Jul 2005 Location: Hull, East Yorkshire, UK. Posts: 2,087	The most suitable valve for an anode-bend detector I am just wondering if there is any characteristic that is particularly desirable. I have got a number of EF91 & I need some use for them! I have got coils & I have previously used Octal EF39 & 6K7 as RF amplifier & detector I was thinking of re-visiting this type of TRF that is the type used in the legion of kit radios, but updated slightly

19th Dec 2013, 9:16 pm	#2
G6Tanuki Dekatron Join Date: Apr 2012 Location: Wiltshire, UK. Posts: 14,007	Re: The most suitable valve for an anode-bend detector Is it a regenerative detector? I've generally found that non-variable-mu pentodes are best in such duty, though low-slope variable-mu pentodes [such as the 1T4/1S5 battery valves] are OK in such applications. An EF50 works well as an "infinite impedance" detector.

19th Dec 2013, 10:17 pm	#3
FERNSEH Dekatron Join Date: Mar 2005 Location: Gateshead, Tyne and Wear, UK. Posts: 7,444	Re: The most suitable valve for an anode-bend detector In my simple superhet project I chose a high slope pentode for the anode bend detector. At present I'm using a Mazda 10F1 because an UF80 was not to hand. Other valves such as the EF50, EF80, EF91 and 6F1 work equally well. Octal fans could consider the 6AC7/1852. The circuit of my superhet is here: http://vintage-radio.net/forum/showt...=101388&page=3 Post No. 48. DFWB.