VLF MD (by Sascho - Varna)

[nikko10]

Good afternoon, I looked through all the pages of the topic and there is not a single publication of the board in LAY, here, please, please check, maybe I put something wrong in the denominations, the pinout of the transistors. If there are errors, please correct them. is it worth adding to the board?

[emoxristov]

Here's my new motherboard

[emoxristov]

Please give some info on how to properly connect the antenna transistors

[Pompey]

Hi,Salih!At your post #188,#189 you have reversed pins of transistors.From left to right it should be c-b-e .At your picture : e-b-c !

[scs]

Coil connection.

[salih]

idea

Show us your idea

[salih]

VLF MD (by Sascho - Varna)

This is the way that was connection to the transistor and search coil .If you have a better idea, I will be glad to Correct picture attached.
Greetings

[scs]

This scheme work with high amplitude oscillatory and low amplifier gain.Noise is not problem.

[Davor]

Of course. My goal is obtaining nice noise figure by direct method, coupling a coil directly to a real low noise preamp, and that would provide a very monotonous phase change there. Even a series resonance in this configuration has a very little and monotonous phase change.

There are many ways of achieving superior noise to mid range op amps.

[scs]

If you change the resonant frequency of the receiver changes the phase of the signal.

[Davor]

Hi scs,

I have a small request, and a comment.

I wish to use this kind of coil compensation in my future designs, and I am aware that this is not a new idea, yet you are the one promoting it, so... Is it OK by you if I use it?

A comment is about the Tx oscillator. In my sims of a balanced oscillator, and your oscillator IS a perfectly balanced one, I found that adding capacitors in the base circuitry moves a phase in way favourable for off-resonance oscillators. Your capacitors are at 10nF, which is on the safe side, but the effect is still there.

[scs]

In the main control box of the small board.Make coil position without compensation.

[WM6]

Hi scs, thanks, do you suggest to build this modification in coil housing or in main control box?

[scs]

Detector modification.

[scs]

Exchange in oscillator transistor base-minus resistor 68k to 100k.Not transistor problems.