Lambda diode - two versions

I posted this text book version earlier. It does work and is high voltage version.

Yes it does function. Note the voltage. 100 volts in sim about 70 minimum.

The power level is high. It might make a good CW transmitter with a little tweaking?

This is the one I use. It function with a single cell power supply. The sim is at 9 volts. I  have used plug in coils up to 14Mhz.

In my circuit R1 is a pot used to set the current limit.

Amp in a can

The can is 2" diameter and 3/4" deep.

It will need more testing but it does buzz the earbud with my generator set to min.

turret board or pin board options. Direct conversion receiver.

Perf board is good. What if you have none?

My new go to amp on perf board.

Peg board for DBM.

A piece of wire and a pair of pliers to make turrets.

Smash the end and cut it .

By drilling a hole to fit the round part and inserting it you make a turret board or pin board. The flat being larger prevents its going thru.

This amp uses some of the pins. With a 1300:8 transformer it drive a small speaker to easy chair volume. The face plate and base board are masonite (pressboard - hardboard) that I laminated with heavy duty aluminum foil.

*** the coupling capacitors should be 10Ufd. I miss tagged C2.You could use .5Ufd or larger. The larger capacitor will give better low frequency response.

This is the schematic. I just numbered the tie points and connected the dots with the components. The circuit works well with an earbud. Adding the transformer and speaker works too.

These are good transformers BUT you must handle them with care. If you let a pin turn it will break the wire. It would be best to solder the transformer to a board and solder the wires to the board. Making and eye on the end of your lead wire and not putting it in a strain is second best.

The pin shown hear would be crimped in the middle and inserted thru the board allowing a connection on either side.

One more option if you have any.

The DBM ready for testing.

This is basically my radio except I used the Lamda Diode Oscillator. I like the LDO because it sings with any coil I put on it. I think the circuit above is a Les Haywood original from 1968. Last night I listened to a couple of hams talking in NC. With this set. It would be about 600 miles.

2 transistor radio

Adding a second stage to the circuit developed in the last post.

transistor biasing - simply method - one transistor radio - fixed base biasing

A simple no nonsense transistor biasing method.

The R in this example is 330K. The circuit will be like this.

This could be a one transistor radio using the transistor you have on hand. Use the headphone resistance to set Vc to 1/2 Vcc.

Some transistors have a very wide ß range. You could test the one you have and use the measured value (or be aware of the broad range and vary R if it fails to function as expected.)
Modern transistor have a letter suffix which defines the ß in smaller segments because of the variations.
This is the simplest method and the most unstable. A circuit like this is more subject to temperature and component variations. Using the high ß and a low Ic will produce good results. A high power circuit will require more components to provide stability and protect the transistor from burn out.

Using general purpose components -OR- TUN TUP DUG DUS circuits

This 1974 magazine uses general purpose parts to design and build circuits. A reader could build the circuits with whatever they had on hand and not be trying to locate and buy parts specified in the magazine.
It is a good plan so I'm posting the article. The names are a little strange and it doesn't allow for Germanium transistors but it is a start.

I use this ohmmeter test but use a 1K resistor.The skin resistance can vary quite a bit. The 1K resistor gives repeatable results.

A sample circuit from the same source.

The amps I've been building have been using Germanium transistors. I've used GSS109, MP40, MP16, MP39 and P416 with good results.

Where to buy Variable Air capacitors

Variable Air Capacitors

Follow the link and you will find these for sale:

Good product and good service. The V- Cap is the hard to find item today but Mike has them. Now you know you can get one and get building.