VE6BLD

ve6bld

Welcome to the CAARC web site. I have been a Ham since 1978 and am active on most modes from HF to UHF Satellite communications.


Posts by VE6BLD

AD9850 DDS VFO By Earl Rubin 4Z4TJ

AD9850 DDS VFO
Earl Rubin 4Z4TJ
While shopping on line I came across a AD9850 DDS Signal Generator Module (http://www.banggood.com/AD9850-DDS-Signal-Generator-Module-0-40MHz-IC-Test-Equipment-p-915819.html ) and, of course had to have it. After it arrived I started to look at the possible applications and came across Richard’s website: http://www.ad7c.com/projects/ad9850-dds-vfo/ . I believe that this is a good module to work with because they are widely available on eBay at low price, there are many on line descriptions, you-tube videos and other information….Please click the following link for the full article

AD9850 DDS VFO 1

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Easy prototyping of PCB boards By Earl Rubin 4Z4TJ

Easy prototyping of PCB boards
Looking for a way to easily make “Manhattan” style PCB breadboards I re-discovered the “Islander” – see reference 2 below, but was unsuccessful in finding a way to purchase one. Then I found Andy Davies’ You-Tube video describing his home made land cutter. Not wanting to wait for a ¼” drill bit to break of its own accord, I sacrificed the dullest 7 mm bit in my drill box.
First I clamped the bit horizontally into…Please click the following blue link for the complete article

Easy prototyping of PCB boards

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RFI considerations when converting to LED lighting By Earl Rubin 4Z4TJ

RFI considerations when converting to LED lighting
By Earl Rubin, VA6TJ
I installed my new LED ceiling fixture in my shack. The light fixture consists of a flat panel of LEDs mounted in an aluminum frame that also contains a small switching power supply..  Before installing the new light fixture I thought it might be a good idea to check RFI on HF….

Please click the blue link below to download the complete article

AD9850 DDS VFO 1

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NEW CAARC Executive for 2014-2015

The Annual General meeting of CAARC was held on Tuesday November 18th at the new Red Deer County Search and Rescue building. Ric Henderson VA6RIC ( Director of Community and Protective Services) gave everyone a tour of the new facility and equipment.

The new executive for the 2014-2015 year is as listed below.

Thanks to everyone who attended and congratulations to the new executive.

I look forward to working with you over the next year.

Bob VE6BLD

Past President – Sandy Jacobs VE6SND

President– Bob King VE6BLD

Vice President– Steven Lee VA6SGL

Secretary– Bill Jackson VA6BLL

Treasurer– Karen McKinney VA6LDY

Directors

  1. Brian Davies VE6CKC
  2. Neil Rowe VA6AK
  3. Rick Koinberg VE6RAK
  4. Bob Bryce VA6TRB
  5. Bryan McKay VE6JPW

Appointments
Repeaters

Skip MacAulay VE6BGT

Emergency Coordinator
Jeff Low VA6JL
Publicity
Geoff Norris VA6TAC
Webmaster
Bob King VE6BLD
Net Control
Bob King VE6BLD

JT65B digital HF

I received some nice DX today on JT65B! Check out the pictures.

JT65HF6

 

VA6DX FPV Flight over Red Deer Picnic

From Barry Bergstrom VA6DX

Hey Bob. Here’s a quick video of the FPV flight from last weekend. You’re welcome to embed it on the CAARC site if you like; just but a note on to watch it in 720p or 1080p for a better effect. 

Thanks Barry great video

Bob VE6BLD

 

 

Google Calendar

FOX Project Cube Sat

Reprinted from AMSAT NA
Phase 1 Fox satellites are 1-Unit CubeSats. They each include an analog FM repeater that will allow simple ground stations using an HT and an “arrow” type antenna to make contacts using the satellite. This was the mode made so popular by AO-51. The Phase 1 CubeSats also have the capability of operating in a high-speed digital mode for data communications. Two of our phase 1 Fox satellite projects have already been accepted into the NASA ELaNa program for free launches.

Preliminary Fox Keplerian Elements

We now have a launch for Fox-1 in 2014.  These Keplerian elements approximate the perigee, apogee, and inclination of the orbit.  They have been tested in several popular tracking programs, and will give a good feel for the availability and footprint to be expected.  Other details will depend on the launch site and deployment profile.

FOX-1
1 99999U 13001A   13115.03159480  .00000000  00000 0  00000 0 1    14
2 99999  64.0000 106.4735 0200000 270.0000 180.0000 14.81480000    10

With the IARU coordination received, the uplink frequency will be 435.180 MHz, and the downlink frequency will be 145.980 MHz.  For those using the SatPC32 tracking program, you can add the following line to the DOPPLER.SQF file:

FOX-1,145980,435180,FM,FM,NOR,0,0,Preliminary

We will update these as the launch approaches and more specific information becomes available.

Fox-1 Engineering Prototype.

Ham Radio on the International Space Station

The International Space Station Expedition 25 landed on Nov. 25, 2010.

Station commander Doug Wheelock gave a great tour and demonstration of the Ham Radio on board before he came home.

Testing “generic” MOSFETS for RF PA use

Testing “generic” MOSFETS for RF PA use

Earl, 4Z4TJ / VA6TJ

Low cost plastic MOSFET transistors can be used to make effective low power HF PAs.  I have an amplifier I made with IRF510’s that effectively brings a Softrock transceiver output up to legal QRP (5 W out) with a 15 volt power supply.  With that experience in mind, I started looking for plastic MOSFETs that were actually designed as RF amplifiers, and not as components in a switching power supply.

A while ago I bought some supposed RF MOSFETS on eBay from a supplier in China.  I did not take sufficient care in checking out the history of the parts that are marked MS1307 from International Rectifier.  A bit of Googling around showed that IR never made a transistor designated MS1307.

I decided that the transistors needed to be tested under actual RF amplification conditions, and not just with a multi-meter.  Therefore I build up a simple test circuit,  based on a 40m CW xmtr by VA3IUL, where I could plug in a MOSFET and test it as a 40m amplifier.   The transistor socket was taken from the wiring harness of a discarded ATX computer power supply.  The source of Q2 (tied to the emitter of Q1) needs to be grounded to obtain output – this is where the CW key would be attached, or in my case I soldered in a micro switch.

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0.5 W out into 50 ohm load through LPF (5 v/division;  10 V P-P).  Supply voltage = ~12 V

 

Initial results can be seen from the photos on the previous page.  The transistors do amplify in this circuit and I can get a nice waveform if I adjust the gate bias (R5) voltage to give a maximum 1 W output into 50 ohms.  Adjusting the bias to exceed this power level causes the scope trace to turn ugly showing that bias has shifted the transistor off the linear portion of its load-line.   What needs to be done to determine the operating limits is to vary the input level to the MOSFET gate while maintaining the bias so the transistor is operating in its range and at different supply voltages.  This is a good reason to buy a nice signal generator  J

With the simple setup shown in the schematic at a supply voltage of 13.6V, PA voltage gain as measured with the scope probe, was determined to be approximately 15 db.  Vin = 4 V P-P and Vout into 50 ohms = ~25 V P-P.

After this test, I thought about improving the impedance match into the MOSFET gate and buffering the output of the crystal oscillator.  I adapted a section of a circuit from one of my Softrock transmitters and came up with this:

This circuit did not do much to improve the waveform going into the gate of the MOSFET but it did permit higher output power with a nice sine wave after the LPF.  I could easily obtain  1.5 W out with a 13.6 V supply and a MOSFET gate bias voltage of 4.0-4.1 V (measured with open source).

 

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I also tried reducing the bias on the oscillator transistor Q1 base by lowering the value of the base to ground resistor to about 2/3 the original value.  This did not have any noticeable effect.

 

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Breadboard with the added buffer amplifier and 9:1 input transformer to the MOSFET gate

 

I do not consider this circuit to be a useable transmitter.  It’s a test jig for performing  a rudimentary check on RF MOSFETs or picking a matched pair.   As a transmitter the circuit is not appropriate: the leads are too long; there is no thermal protection in the bias, etc.  For these reasons I am not going to invest effort in testing at a higher frequency.    However, I did listen to the 7.3 MHz output (into a dummy load) on the station transceiver and, in fact, the CW sounded just fine, no key clicks, shifting notes or other QSD.

After a suitable number of cups of coffee the next morning, I realized that L1, R6 and C2 are to zero beat (pull) the crystal frequency when operating CW and are not needed for a test jig.  If you remove them, it may be necessary to increase the value of C1 .

 

 

 

Planned improvements:

  1.  Add an ammeter to be able to determine DC efficiency.
  2. Regulate the bias voltage supply.
  3. Compare RF amp results using different switching power supply transistors
  4. Determine the effect of increasing the supply voltage to 24 V.

 

I recommend checking out VA3IUL’s website http://www.qsl.net/va3iul/ where there are many circuits and ideas for projects.  Thanks to Iulian for his assistance with this little project.

 

Earl, 4Z4TJ / VA6TJ