TRF Receiver

[Murphyv310]

Perhaps add a little reaction on the first stage, it should liven things up I'd imagine.

[BusyBee]

Yes that sounds like a good idea, possibly easily achieved with my ferrite rod setup. When I get sorted on isolated testing somewhere else in the house I will give it a try, thanks.

Tracy

[Geordie McBoyne]

I have had in my possession for too many years to remember the empty case of a Burndept model 272. A similar Vidor branded version was also made. The sets were made in 1939.
The receiver is a simple three valve TRF. The RF amplifier was a Mullard VP2, the detector another VP2 and the output is a Mullard PM22A.

The receiver has an internal frame aerial and to date that's the only component that has been made for the set.  Ed Dinning kindly made and tested the new aerial for me. Excellent Q figures.

A better substitute for the huge VP2 pentodes will be the Mazda VP23, filament consumes only 50mA compared with 180mA for the Mullard VP2 and 135mA for the VP2B.

Even better than an internal frame aerial is a ferrite rod, was such an aerial used in a commercially made TRF radio?.

Geordie McBoyne.

[BusyBee]

This is where my lack of experience is showing, as I am pretty unfamiliar with any of the valve sets which used ferrite rods although I have occasionally come across them. From the general information I have found it looks like TRF sets would be rare or even non-existant by the time ferrite rods became commonplace in commercial radio.

https://www.radiomuseum.org/forum/first_...tenna.html

Tracy

[pwdrive]

They were used in kit TRF receivers such as the Roamer and the Micro 6 etc.

Lawrence.

[Geordie McBoyne]

Here's the circuit diagram and parts list for the Vidor 272 and Burndept model 274.
Note the that the Mullard VP2B is a hexode. In these receivers these valves have been connected up as tetrodes, that is G2 and G4 strapped together and G3 to ground.
Cossor 210 HTP is likely to be an equivalent of the Mullard PM22A.

Geordie McBoyne.

[Geordie McBoyne]

More information for the Vidor 272 and Burndept 274.

Geordie McBoyne.

[BusyBee]

Thanks for those. I will have a good look at the circuit. I know mine is a bit lacking in comparision with these old circuits with fewer valves, so I need to grasp the reasons why.

Tracy