Hi Kay Pirinha , I use the EF183 ( variable mu pentode ) like cathode follower - triode connected , with very good results . Did you try any EF183 before ? .
EF183 can be used with good results instead of EF89 (which is the typical IF-tube in german radios) in tube-receivers. Selectivity is increased due to higher transconductance.
speaking of cathode followers, I mostly switch to ZETEX ZVN0545A (Thanks to Eli Duttman) because even after hours, I can't hear a difference to a (proper) tube.
speaking of cathode followers, I mostly switch to ZETEX ZVN0545A (Thanks to Eli Duttman) because even after hours, I can't hear a difference to a (proper) tube.
Yes , EF183 and EF184 has disigned to replace the EF85 , EF89 ( vari mu ) and the EF80 ( sharp cutoff ) . The EF183/184 have special internal construction .
No, I didn't, Dimitris! But as in a cathode follower cathode voltage follows grid voltage, there's no matter if you use a sharp cutoff or a variable gm tube .
You mean the frame grid construction, don't you?
You're quite right with the EF80/EF85 vs. EF184/EF183 relationship, but the EF183 never replaced the EF89. It was especially designed as an IF amplifier in TV services, not in radios. Succedessor to the EF89 was e.g. the EAF801, which combines the same pentode system with one diode, or, to be exactly, has extracted one diode out of the EBF89 with the internal screen connected to the pin formerly used for that diode.
Best regards!
Gain is increased. Selectivity may change due to potential instability. EF183 is not designed for radio receivers, but low impedance wideband TV IF strips. EF89 is better for radio, as it has better handling of strong signals and low feedback capacitance.the_manta said:
Yes Frame Grid that's what I mean , and you have right about the EF89 it has nothing to do with EF183/184 . I say EF183 because you can't use it in amplification stage due to it's variable transconduction charecter ( I prefer Brimar EF183 it sounds good ) , and if you use it as cothode follower it will not introduce any distortion since there is no gain , as for the EF184 it's obvious that you can use it in the two cases and as CCS too .
You're right DF96, the EF183 was designed for TV sets. Years ago I did some tests to substitute the standard german radio tubes with other "useless" tubes. The EF183 often did a good job instead of the EF89 in one of the many radios around here. The cheap russian 6n1p did also a good job instead of the ECC85 but it depended whether the RF-amplifier was grounded grid or common cathode type. Both topologies are very common.
Didn't know that with the feedback capacitance though.
EF89 is designed for high impedance stages, such as 455kHz AM. Also OK for 10.7MHz FM.
Variable-mu valves are not ideal for cathode follower, but the EF183 has sufficient gain that you can get away with it. More interesting is the circuit which uses the low gain EF92 as a CF; this is likely to add some 2nd - not sure if that is the desired effect or an accident.
Variable-mu valves are not ideal for cathode follower, but the EF183 has sufficient gain that you can get away with it. More interesting is the circuit which uses the low gain EF92 as a CF; this is likely to add some 2nd - not sure if that is the desired effect or an accident.
yeah the EF183 183 are of a special breed . pretty lineair . disecting it shows pretty heavy duty cunstruction frame grid 😀 and a
big cathode that looks better on a 7 watt beam pentode than this little fella .
should be good upto big currents . i wonder if the increased current will lower noise ?
those PC88 86 E types are nice to use whit a LM317 in voltage regulator mode folowed by a current sourced LM317
getting it not to oscillate might be hard as these things will .
big cathode that looks better on a 7 watt beam pentode than this little fella .
should be good upto big currents . i wonder if the increased current will lower noise ?
those PC88 86 E types are nice to use whit a LM317 in voltage regulator mode folowed by a current sourced LM317
getting it not to oscillate might be hard as these things will .
There is no need to increase current in Frame Grid tubes to reduce noise , since they are usually low noise tubes due to their high transconductance , and they designed for that .
Yes, the output noise of a frame-grid valve is no better than any other; it could even be worse. The high transconductance means the input-referred noise is low. I'm not sure how relevant this is to a CF.
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