100mW - VHF- 2M - TX

Low power compact and light weight VHF 2M TX .
The output power =100mw@.5VDC.
Apart from a couple of  Hertz drifting on start-up.
I was impressed with the frequency stability.
In testing I found it easy to forget that this TX is just  pro-type module !.
Stability led me to connected  my sound-card with UISS beacon on !.
On other side of the bound  (ie cross the workbench) I've copied every single beacon frames.
Did I hit the ISS with this low power ?? GOK.
Next pass,I'll try to hook it to the Yagi :-))

 

NiCd/Ni-MH automatic charger

A nickel–metal hydride battery charger is the new accessory to the workbench.
Most components were recycled from an old PC monitor.
The starving (MFJ Antenna Tuner) will be so happy now :-)) .

Baycom Modem !

A simple modem that functions the same as the classic "dumb" Baycom Modem.
For modulation a monolithic phase-locked loop (PLL) IC xr2211 used.
The demodulation  XR-2206  a monolithic function generator was used .
Calibrate the Mark tone 1200Hz at low TXDATA level , and
the space @ 2200Hz at high TXDATA .
Why do I need to build such an old style modem ?
1st because it a piece of the digital communication history .
2nd its a very good demo tool for the digital modulation topics.

USB VOX

USBVOX

Enjoy your favorite music and save a com port, if there any port !
USB sound-card + a handful discrete components  .
Works with any digital software .

An old photos of my Homebrew Satellite Tracking Equipments.

 An eggbeater Antenna - For NOAA weather satellite .

FODtrack Rotator interface with AZ/EL driving relays
Used with a modified CCTV Camera Rotator
as on next photo.

 UHF/VHF cross Yagi  antennas with changeable circular polarization coax phase lines
  and remote control DC switches.
The rotor mod include adding a voltage feedback potentiometers.
The AZ-Pot  connected  mechanically to AZ moving part.
The EL-pot driven by  a  hanging  weight ( NUT)  to the gravity .

 High gain UHF  Yagi with cross elements and switching circular polarization

RHCP/LHCP

 The VHF Pre-Amp - Transistor was BF981
On services since 10 years
No TR/RX relay . peaked to 137 MHz for receiving the weather satellite  .

 CI-V interface built on perforated PCB - with external DC power supply

 PC sound card interfacing 

later 1:1 isolation transformers were added

VHF/UHF on single boom

You Can't Resist !!

At a cold winter night you can't resist listening to a DX station with a great signal.
Since I built the DC Rx last month  I've  shut down all other fancy black.boxes.
The Rx still  sitting on the workbench in parts connected with jumpers.
The antenna is just a loosey goosey long wire .
Why should I do this? Because it's fun.

   

                              

putt putt putt

 Audio amplifier motor-boating sound.

Adding a Pre-Amp in front of the LM386 creating a Motor-boating sound when I increased the audio volume .

Obvious wasn't  due to interaction between audio amplifier circuit and radio frequency circuit .

A good shielding and power supply decoupling may solve this .

See 30 sec motorboating video clip .

                      

Ancient reduction gear

Reduction gear mechanisms are often used to achieve finer tuning control for variable capacitor .The turning  ratio is 6:1


                                                          External  reduction drive

                                  

                              

20M DC Rx initial test

Direct Converter receiver  Initial test .

 No shielding or band spread yet ,but the stability and sensitivity was so good for this prototype Rx.

                      

20M Front-end filter

Front-end filter

Bandpass filter for 20M - Tested at Satellite Communication Lab (SCL)
University of Khartoum .by Cube-sat engineers.
 

                        

MC1496 Product Detector

MC1496 Product Detector .
 All components are easy to to find except the old MC1496 . luckily I've got one piece.
Initial tests gave a good result. Injected 14 MHz at 1st input and  RF via  a long wire to 2nd input (without pre-selector ) . Next  I will add pre-selector and 386 IC.

Back ground -Solid State Design by Wes Hayward W7ZOI and Douug DeMaw W1FB .

20M VFO

QRP Weekend ,Workbench !

Back to Crystal Radio fun.

A crystal radio is a very simple radio that was popular in the early history of radios. It is a great project for Kids .In this clip my son Mazin shows a crystal radio set and how its works.

Week-end project for my son.

Keeping my son busy with a simple week-end project.

Stirling engine by my son

Regenerative Radio RX

مشروع اليوم جهاز استقبال في غاية البساطة وقد قمت بتجميعه واستخدامه بكل يسر.

ويمثل حلقة مهمة في تاريخ صناعة المستقبلات اللاسلكية

http://www.electronics-tutorials.com/receivers/regen-radio-receiver.htm

للاسف قد لا استطيع الان وضع صور له او ترجمة للرابط .

لا اني قد قمت بادراجه فيكتابي القادم ـ الصناعة المنزلية للهواةـ والذي باذن الله ساحاول ان اكمله بالقريب العاجل .

المشروع بسيط ويمكن به من استقبال الهواة علي عدة نطاقات والجميل ان باستطاعة

هذا المستقبل ان يستقبل انماط مختلفة مثلssb cw am يدعي بالانجليزي

مستقبل ال regenerativeاو اختصارا regen ريجن

lots of junk

Lots of junk

Edison was asked what a fellow needed to become an inventor.

He said, “ First you need a large pile of junk. You can’t afford

the time and money to run down to the store every time you
need something. Often the junk pile will supply the parts to try

out an idea right away. If you order parts from hundreds of

miles away, you may waste weeks just to find out that your idea
didn’t work.”

CRYSTAL SETS TO SIDEBAND BOOK
http://www.qsl.net/k3pd/chap03.pdf