Currently trying to make a valve transmitter.View from the bottom

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

I bought a partly assembled project from another Amateur with no wiring or plan and I am trying to make use of the nice parts.

I have now made a fairly OK Vackar oscillator and buffer amplifier using a 6AQ8 twin triode and will work on the PA final next. Lab Book with Diagram

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Tesla-Vackar

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Vackar-US

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The big mains transformer the kit came with gives out 350V HT.  I have full-wave rectified that and I fitted a VR150 voltage regulator valve via some dropper resistors to create a reasonably constant supply for the oscillator.  There was a series smoothing resistor between two large capacitors which I am contemplating replacing with a mains choke to give a better supply voltage under load.  It will be an interesting experiment anyway!

TX Side

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

I have no experience of PA finals so I am looking forward to it - although I am a little worried about the high voltages involved!  My concern at the moment is the more than doube increase in amplitude of the oscillator signal between 3.5 and 3.8 MHz.

I have to think how I will connect the PA final output to the 50-ohm aerial...

Here are some bench pictures:

Some Bench Instruments

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Components Leads Iron

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

---

 

72 cheers

Nick m0NjP / on4Nic