What's on your Workbench?

General discussion - When it doesn't fit anywhere else
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VK3YE
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Re: What's on your Workbench?

Post by VK3YE » Wed Aug 28, 2013 7:07 pm

The 80m phasing receiver referred to on June 10 has grown more boards, more wires and a lot more mess.

But it's now an operational phasing SSB transceiver. 8 transistors, 1 IC and not a single crystal filter required.
vk3ye unpolished phasing txcvr 002.jpg
Phasing txcvr
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Re: What's on your Workbench?

Post by VK3PY » Thu Aug 29, 2013 5:24 pm

My "QRP" W6PQL 23cm PA, built from the left-over bits of my 300W version. This one is destined for field day operation.
W6PQL_105W_23cm.jpg
W6PQL_150W_23cm_inside.jpg
Note the "snowflaking" of the output hybrid combiner. I did this following a comment by Doug VK4OE elsewhere. Initially the amplifier did not produce the expected gain or output power, requiring about 12W drive to produce just on 100W output (measured at the external connectors, hence internal cable losses are included). Following this mod, the output went up to 140W with just 9W of drive (26.5V @ 9.8A drain supply). The short length of QF141 from the pcb output to the rear panel connector gets quite hot to the touch after a couple of minutes of continuous carrier, suggesting the PA is in fact well and truly coughing up its rated 150W. Considering the length of the UT141 cable on the input side, I'd day it's also producing the expected gain.

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Re: What's on your Workbench?

Post by VK3YE » Sat Sep 21, 2013 2:49 pm

Another phasing SSB transceiver this time for 7 MHz.

Currently working on receive, rejecting the opposite sideband.

Only an RF PA chain, LPF, T/R relay and rx preamp is required to complete.

The top board is the 7040 - 7250 kHz ceramic resonator VXO.

The large board is the phase splitter, 2 x prod detectors, audio phase shift network & 3 kHz audio LPF.

The right board is the LM386 audio amp which provides all the rx gain.
7mhz pgasing.jpg
7 MHz phasing txcvr
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Re: What's on your Workbench?

Post by VK5TX » Sat Sep 21, 2013 7:54 pm

Image

20 watt amplifier for SOTA using two IRF510

Ben

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Re: What's on your Workbench?

Post by VK1DA » Sun Sep 22, 2013 2:51 pm

Ben
I've been thinking on the same lines but am nowhere near a design or the parts.

Please publish your project, preferably in AR but at least on a blog. A lot of SOTA ops would love to have 6db more output.




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Re: What's on your Workbench?

Post by VK3YE » Sun Sep 22, 2013 7:30 pm

VK1DA wrote:Ben
I've been thinking on the same lines but am nowhere near a design or the parts.
Andrew - an amplifier that could meet your needs was described by Drew Diamond in AR and one of his books. It used 2 x IRF510s and put out about 40 - 50w. It could be switched between 80, 40 & 20m.

Simlar circuits are at:

http://users.tpg.com.au/ldbutler/MosfetLinear.htm
http://users.belgacom.net/hamradio/sche ... lifier.htm

A key design consideration is whether to use a 12v or 20 - 30v rail. The latter better suits these sorts of amplifiers. And modern battery technology and the DX-pedition style of many SOTA contacts has made such capacity practical to carry up.

A far cry from DeMaw/Hayward who regarded 0.5 - 1w as the optimum power for QRP mountaineering and recommended the use of dry cells (as late as the mid 1980s). I believe that Hayward has revised up power to approx 2w (CW) given improved batteries in the 1990s-2000s. ZL2BMI also aims for about 2w for is DSB gear. Note that these figures are for longer trips (a week or so) han a quick SOTA activation. However all of these levels may be marginal when communicating with people in noisey environments whereas a 20w SSB signal will do just about anything that a 100w signal will (unless using a severely compromised antenna eg mobile whip on the lower bands).
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Re: What's on your Workbench?

Post by VK5TX » Sun Sep 22, 2013 8:32 pm

Planing to run it on 12-14v

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Re: What's on your Workbench?

Post by VK3PY » Mon Sep 23, 2013 10:03 pm

Here you go, the "HF Packer" amplifier:

http://www.hfprojectsyahoo.com/hf-packeramp.html

I built a version of this using a pair of IRF 510's some 8 years ago when I bought an FT-817. Used it once and never again. Why? Because the FT-817 produces hideous splatter if modulated to the onset of ALC. No, it wasn't the PA. Two-tone tests showed that both the rig and PA were very good. However, under dynamic (speech) conditions, as soon as the ALC "bites" the rig produces terrible splatter as far as +/- 25kHz. You have been warned........if you do build such an amplifier, be sure to keep the mike gain down below the level at which ALC voltage is developed under all conditions, out of respect for other band users.

Chas
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Re: What's on your Workbench?

Post by VK5STU » Tue Sep 24, 2013 11:56 am

Not as interesting as some, but essential none the less. 20 x 1K 5W carbon resistors for a 50Ohm dummy load of reasonable power.
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Re: What's on your Workbench?

Post by VK4GHZ » Thu Sep 26, 2013 9:31 pm

Currently developing a 3-axis digital compass to mount on my microwave dish.



Using the data from the VK Logger Op Info, this should allow me to blindly aim the bastard!
Adam, Brisbane
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Re: What's on your Workbench?

Post by VK2AMS » Fri Sep 27, 2013 5:39 am

gday Adam , thats a neat idea ( and vid), wouldnt mind building one myself could you let me us know where to get the required parts.
cheers mark VK2AMS :D

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Re: What's on your Workbench?

Post by VK4REX » Fri Sep 27, 2013 7:33 am

Hi Adam

You might want to look at the CMPS10, it is a magnetometer and accelerometer in one unit if that's not the one you are using. I have the code working for this and can send you a video of it working if you are interested. I am initially going to use it but they all have limitations in that they still rely on there being no magnetic disturbances in the area where you are using it. I have decided to investigate the dual GPS receiver/antenna approach measuring the difference in the time of arrival of the GPS signal, this will give a true north gps based indication without the gps having to move and will not be affected by magnetic disturbances.

Rex

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Re: What's on your Workbench?

Post by VK2OMD » Fri Sep 27, 2013 7:38 am

VK4REX wrote:Hi Adam

You might want to look at ...
Another possibility that has occured to me are the inexpensive flight controller boards for RC models. For under $30 you get a board with USB FTDI interface, 3 axis gyro, acc, barometer and magetometer... wired up to an Atmega328P in Arduino compatible architecture and sample code from the flight controller sketches on how to use the sensors.

Image

This is a commercially manufactured product based on community developed hardware and firmware... in fact the 'inventor' is in Brisbane. This is the kind of thing electronics enthusiasts do outside of ham radio.

Owen
Last edited by VK2OMD on Fri Sep 27, 2013 11:23 am, edited 1 time in total.

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Re: What's on your Workbench?

Post by VK4GHZ » Fri Sep 27, 2013 9:21 am

VK2AMS wrote:...wouldnt mind building one myself could you let me us know where to get the required parts.
Hi Mark, I'll be creating and sharing a full article (schematic, code, BOM, suppliers list) soon so that others may benefit.
I will probably get 10 PCBs made up, so they will be available on a cost recovery basis and be posted at low cost in an envelope.
VK4REX wrote:You might want to look at the CMPS10...
Hi Rex, this is exactly the module I am using. Very easy to work with and has the capability of calibration. It seems purpose built for this application!
I did briefly fool around with a HMC5883, but they only provide raw 3-axis data, and are not user friendly at all.
VK4REX wrote:... I have the code working for this and can send you a video of it working if you are interested.
No need to send anything per se. Just post it up here so it's available to all.
It very easy to attach code files, and embed YouTube video into a forum post.
Perhaps start a new topic specifically for this?

I didn't mention in the video that I have a jumper that selects between displaying azimuth as Magnetic or True, and you can code your magnetic declination in, to one decimal point.
(Whilst we're in a positive declination region, my code does allow for a negative declination as well.)
Displaying relative to True means you can directly use the info from the VK Logger distance and bearing calculator etc.
Another jumper hides the (fluctuating) tenths of a degree azimuth.

This small 8x2 LCD has negligible effect on the sensor even 4cm away, whilst the first, larger, LCD (a 20x4 that was already on the breadboard) had a dramatic effect.
I will probably separate the sensor from the main unit anyway, allowing more flexibility with sensor mounting, and the LCD in an ergonomic location.
You can easily run an i2c bus up to a metre without dramas.

Yesterday I changed the LCD interface from 8-bit operation to 4-bit, and today I am going to downsize to a 14M2 PICAXE.
(Gotta love the PICAXE family, so easy to work with, and perfect for simple apps like this!)
PCB artwork will be started today, and gerber files off to the fabricators by days end.

:D
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Re: What's on your Workbench?

Post by VK2AMS » Fri Sep 27, 2013 4:33 pm

great stuff adam put me on the list for one! :D

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Re: What's on your Workbench?

Post by VK5KK » Fri Sep 27, 2013 6:22 pm

Hi Owen

Can you please send me a link or "where to find" on the R/C flight controller ... perfect solution for a parallel project here :-)

Cheers

David VK5KK

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Re: What's on your Workbench?

Post by VK2OMD » Fri Sep 27, 2013 6:33 pm

VK5KK wrote:Hi Owen

Can you please send me a link or "where to find" on the R/C flight controller ... perfect solution for a parallel project here :-)

Cheers

David VK5KK
Sure David.

http://www.hobbyking.com/hobbyking/stor ... _Port.html

http://www.multiwii.com/

https://www.google.com/search?q=multiwi ... =firefox-a

You might also find the following interesting:

http://www.hobbyking.com/hobbyking/stor ... ible_.html

This whole project was originally inspired by marrying the gyros form a Wii controller with an Arduino to make a flight controller capable of flight stabilisation.

There are other modules with larger processors, mostly used in platforms for autonomous flight.

Owen

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Re: What's on your Workbench?

Post by VK5KK » Fri Sep 27, 2013 7:07 pm

Hi Owen

Thank you very much ... Project X (remotely pointing a uWave antenna on a tripod using satellite positioners X & Y axis, etc). Have proto'd with Arduino so have some code but really same dog just a different leg action to a flight controller! 3D position should cope with a tripod not properly levelled :-)

Cheers

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Re: What's on your Workbench?

Post by VK2OMD » Fri Sep 27, 2013 7:31 pm

VK5KK wrote:Hi Owen

Thank you very much ... Project X (remotely pointing a uWave antenna on a tripod using satellite positioners X & Y axis, etc). Have proto'd with Arduino so have some code but really same dog just a different leg action to a flight controller! 3D position should cope with a tripod not properly levelled :-)

Cheers

David VK5KK
David, a screen shot from the Multiwii Conig tool:

Image

The artificial horizon and compass all derive from the sensors, the gyro, acc, mag and bar signals are plotted (the model is flying in the hand at this point).

An amazing source of position / attitude data.

I am thinking of a controller for the lawnmower to drive it at a constant linear speed for spraying and this is an inexpensive source of inertial nav data.

Owen

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Re: What's on your Workbench?

Post by VK3YE » Sat Sep 28, 2013 7:05 am

Progress on the 7 MHz SSB phasing transceiver.

All stages are built and receiver working - only transmitter wiring, testing and inevitable debugging required. There is heavy use of bidirectional passive circuitry so little switching is required.
7mhz phasing.jpg
To illustrate the simplicity of SSB, the board below is the guts of the transceiver. Left to right is: 3 kHz audio low pass filter (tx/rx), AF phase shift network (top), Tx mic amp (bottom), balanced modulator/product detector, and RF phase shift network. Switch the cross wires over to go from LSB to USB. All parts are stocked by Jaycar and construction cost is approx $20.
7mhz phasing 040.jpg
Add a VFO/crystal oscillator (on operating frequency), RF PA chain, electret mic, LM386 audio amplifier, RF preamp to put it on the air.

VK3WWW shot this video showing how a similar one for 80m works http://www.youtube.com/watch?v=ZUxvZE2up8g

And JF1OZL used a similar concept for 50 MHz http://www.intio.or.jp/jf10zl/50MPSN.htm
-------------------------
Peter VK3YE http://www.vk3ye.com

NEW FOR 2019! Illustrated International Ham Radio Dictionary. 200 page Kindle ebook. $AU $5.99. Get yours at http://home.alphalink.com.au/~parkerp/dictionary.htm

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