Wednesday, August 17, 2016

CW QRP TRANSCEIVER UNDER $40

AN OLD PICTURE. NOW A SMALL SPEAKER IS IN TRX CASE:


VIDEO OF READY PROTOTYPE:



 


WCA ACTIVITY - LZ CASTLE ACRA - 2016




BACK OF TRX:
BNC antenna in/out, gain control pot, power cord, and arduino cable in/out for further extension if need, audio output after LM386, cw key input.


TRANSMITTER - half part from Chinese Forty9-er, with mods by Dr. Jack Purdum, W8TEE; Farrukh Zia, K2ZIA; Dennis Kidder, W6DQ, and LZ1DPN

1-st 49-er mod:

2-nd 49er mod:

DDS - > ARDUINO + LCD + AD9851
designed from AD7C and VK8BN :



DDS RF buffer + Power Supply 12V/5V :

RECEIVER
Direct conversion receiver designed from SM0XGY :


TX/RX RELAY CONTROL


AUDIO
Audio amplifier with LM386 (from somewhere in internet):

I'm use a Chinese Forty9-er from eBay , and receiver developed by SM0XGY, in his web site

http://www.waveguide.se/?article=ne612-receiver-experiment

Please, read the entire document: Purdum0316-QST-in-Depth-AssemblyManual.pdf

All changes are based on it. And I'm make few modifications in schematics from this pdf.  This PDF I've use only to assembly "Chinese" Forty9-er, because I'm build other DDS oscillator (not this from original pdf). Respectively,  My arduino code is modded on the basis from AD7C and VK8BN sketch.

In Chinese Forty9-er scheme, I finally change the count of LPF winding to run from 0 to 30 MHz  Remove several winding from L4 coil,  and replace 2 capacitors C17, C18  to 100 pF  (I don't remember now exactly, but I made LPF from 0 to 30 MHz, with an online calculator).

I also remove the consistent LC group (scheme LxCx - 1st mod in top pictures),  which replaces quartz and put a wire to bridge, to eliminate interruptions in his place.  And also remove the capacitor before quartz, to stop any frequency filtering.

After many tests I'm replace the both end transistors (in driver and PA) in transmitter stage: for Q6 - 8050, I put 2n3904, and instead of Q5 - D882, I am use BD139 with heat sink (not provided in the kit). I'm burn many BD139 and now use in ColectorEmmiter end 43V Zener Diode to protect end transistor.

ALL DATA FILES, PICTURES, LIBRARIES AND SOURCES YOU CAN DOWNLOAD HERE:

https://github.com/LZ1DPN/CWTRX0to50MHz-v1/


73 ES MNI DX'es!LZ1DPN