Keeping radios working following analogue switch off.

[Phil G4SPZ]

Glad someone's awake... Yes, Kalee, congratulations for spotting the deliberate mistake! It is indeed a 12SA7

[A35Z5GT]

Originally Posted by Phil G4SPZ

I already do something very similar. My micropower transmitter uses a 12AS7 and I prefer to transmit dance band music from the 1930s, which sounds exactly like it would have been heard by the wireless listeners of that period.

Due to the remote cutoff characteristic of G3, the average 12SA7 will only modulate the RF signal approx 35% before distortion is a problem... Replacing the "SA" with a 12CS6(requires miniature 7 pin socket), will yield a Tx producing a fully modulated signal...

Tom

[G8HQP Dave]

Originally Posted by PJL

Radio broadcasting in the traditional sense would seem to have a limited lifespan. Streaming audio/video over the internet and Cellular Networks is the future whether we like it or not. Distributed connectivity over optical fibre making local connection via WiFi or Cellular offers huge advantage with unlimited 'stations' and the oppportunity to charge for it. I can easily see a scenario where there is no 'free' radio service.

I agree that looks like the way things are going, but it seems a terrible waste of bandwidth to send individually addressed packets to individual users when you could support 100's of thousands or millions by simply broadcasting over the air.

How are these internet-based systems going to cope when, say, all five people in a household all want to simultaneously watch a different film? I am not convinced that these systems scale up properly.

[TIV48]

hi i have built the itx see pics on face book site works very well , good kit for £39

[Phil G4SPZ]

Originally Posted by A35Z5GT

Due to the remote cutoff characteristic of G3, the average 12SA7 will only modulate the RF signal approx 35% before distortion is a problem... Replacing the "SA" with a 12CS6(requires miniature 7 pin socket), will yield a Tx producing a fully modulated signal...

Tom

Thanks for your interest, Tom! I have experienced audio distortion with this particular design, believed to be a Chas Miller 'Radiophile' circuit, originally built by a friend Graeme G3GGL and recently restored by me. I'll look into the possibility of converting it to use a 12SC6.

Is the heater current of the 12SC6 the same as the 12SA7? Perhaps we had better continue this discussion via Private Messages as it could take the thread off-topic.