AmateurRadio.com

Calibration of the M328

I have previously explained how to go about building the M328 in Part (1)



Now this is where it all gets very interesting!

When I watched the VK3YE  video (A number of times may I add), I had always wondered about the 35pF offset and why Peter couldn't eliminate it? I had read the manual written by Karl-Heinz Kubbeler, upside down and inside out around the area of calibration (Section 3.2). I had felt maybe Peter had missed a step, or maybe two? But it would only be when I finally built the project I would be able to put my theory into action! After all I couldn't just pop over to Melbourne and explain, it is not a couple miles down the road from the UK is it, and doubtful some nut with a theory would be welcome asking for a phone number anyway??








Before you start calibration you will need to make yourself a three pronged shorting link, and a get a 100nF (0.1uF) Capacitor. The Value can be greater, but not less than 100nF, which will be required for the final part of the Cal procedure:







You then insert the link into all three terminals (1,2,3) on the bottom terminal block, make sure the connection is tight. Press the On button this will put the unit into Self Test Mode:




When it gets to "T4 Isolate Probe" which I assume means Test 4? Remove the Link smartly! Do NOT touch any parts of the unit:






Let it move on, until it gets to the last screen which at this point you will require the 100nF Cap and Insert it between Terminals 1 & 3



Leave the Cap connected, you will see this value pulsate on the bottom line of the display as it is calibrating. Mine read 91nF. It will keep pulsating the value until the test concludes (can take about 2 mins?). When the test finishes it will exit the calibration mode as indicated on the display, reverting to testing the Capacitor and indicating the value being tested as below:

(Sorry about the breadcrumbs on the bench, this is how one works when into resolving problems)
 



The unit then times out after about 30 secs and switches off.

Now if you have gone about this procedure correctly, when you next turn on the unit it will no longer display the 35pF offset as shown at the start of this blog,  the Display will show the following after the initial Volts check and sign on etc:

 


You are now ready to start testing your components. Which we will come to in Part 3.

Notes:

Shortly after I proved my theory about the elimination of the 35pF offset, I contacted VK3YE via email. Peter came straight back with a BIG thank you, after he too had tried my method out, and it had worked on his unit first time! The only problem he had found, he couldn't then test small value capacitors? Eg: 47 pF measured fine (48pF) but 22pF was not recognised Hmmm!

I spent my teatime reading the manual again, and found it!:
 




 

Interlude time now, in between writing up the Calibration procedure for the M328.. We will push this little one in to keep you all happy.

I have a few various projects to build over the next couple of years, some that will require a regulated supply to feed various DC Volts  (low noise is a must!).  I had been running through my mind various ideas using regulators on some stripboard to mate up  the supply rails,  I had a few emails between my friend G0FTD  on the subject, he said take a look at these "5" seperate LM317 boards already made up on a PCB, complete with heatsinks for just over £5 ($8 US), which works out at just over £1 each! I couldn't even buy the heatsink for a £1 over here, never mind the LM317 and the PCB.  I ordered five they arrived within 10 days from HK, a couple of  the LM317's were not bolted up tight to the heatsinks, but a quick tighten with a screwdriver and all was ok, what a bargain!




Time to test one.
Most of what I will be requiring is between 3.3V and  5V with a 12V dryfit battery on the input end.

To prove I just rigged up a quick lash up with 15V feeding one module from my bench supply:



I was able to able to obtain a precision swing of between 1.25V & 13.5V as the the output is made variable with a multiturn pot attached to the PCB, ideal for what I am looking for. 






Conclusion: Another good purchase from China that is useful, money and time saving in project building!

Not only have I come across various types of regulator modules (some switching types so be careful!), but also LM386 Audio Amp modules, Timer modules and even a 3 Axis Magnetometer PCB built and ready to go!



 

Having being inspired by one of Peter VK3YE recent video's, it was time to purchase a couple of kits and dust the soldering iron off the shelf and get down to building one:

This could prove to be a very useful piece of component test kit, for the constructor and repair bench, including the novice. It does, R, L, C  including ESR, Diodes and Transistors, giving the pin configuration detail of the Semiconductor device undertest as well as the useful gain figures. 







It is basically a copy of the Karl-Heinz Kubbeler design, centred around a programmable ATMEGA328 microcontroller which is very well documented. The kit took about 2 weeks to arrive from China, which contains a well made PCB, display module and all the components, including the blown main chip all for around £8.00 ($12 US). It comes with no instructions on how to put it together, but a Chinese manual is downloadable from the purchase site, which I will make a link available at the bottom of this Blog. Infact, really you don't need the manual for construction, as the component values are printed on the PCB, it just helps a little to get one or two things installed the right way around like the switch, and the circuit diagram can be useful for component reference and maybe fault finding later? Of course the Chinese manual is written in Chinglish, we are refered to welding not soldering! I don't think my old arc welder would prove very suitable for this project somehow? Hi!





I emptied all the components out of their anti-static packet into an empty biscuit tin, so I didn't lose any of them. I was away, it took around 2 hours of soldering, and sorting out the correct values, a DMM can help with the resistors values, as I found an orange band can look like a red, so its best to measure them to avoid confusion and getting one soldered in the wrong position. Transistors are marked to board values, and the marking of the outline makes sure you cannot put the devices in the wrong way around.

At this stage it is time to check the board over for shorts, man made solder links etc, and snip off component ends. All looked ok, time to connect the 9V battery, before inserting the main ATMEGA IC, at this point a DMM is required to check for regulated 5V at the IC socket pins 7 & 22, all confirmed correct and the regulator was doing its job!  
 
All in all it was quite a relaxing project to put together, I didn't find anything too difficult, although a bit of care is needed aligning up the pins of the main chip before pushing firmly home into its socket.




 



There is not much work to do with the display board as most of this is already constructed, just a strip of header pins that carefully require soldering in across the top of its PCB. This then mates up with the socket strip on the main board when it is pushed home and bolted together. 




All looked good time to switch on! If it fires up correctly one push of the On button should turn on the display. In my case it did, and didn't? When I released the Push To Make switch, it went out ? Some folk have had problems putting the switch in the wrong way around, I knew I hadn't done this and a quick check confirmed the switch had been inserted correctly, time to investigate further? The clue was the LED under the display board wasn't on, a quick check with the DMM around the circuit in this area confirmed my thoughts, I had put the LED in the wrong way, huh! Oh dear! I had to pull it all apart, split the two boards desolder and turn the LED around, and then put it all back together.








Great it then fired up correctly, and held in its On state after pushing and releasing the button, a quick adjustment of the contrast pot to get the display correct and all was looking well, time to calibrate..

To be continued in part 2.

References:

This is where I purchased the kit from, although they are available from ebay too:

http://www.banggood.com/DIY-Meter-Tester-Kit-For-Capacitance-ESR-Inductance-Resistor-NPN-PNP-p-929603.html  

Construction manual:

https://www.dropbox.com/s/zpjwo3vfv9yfr5b/SKU136841%20M8install.pdf


Design manual helps with Calibration and other stuff:

www.mikrocontroller.net/attachment/143813/TTester_096k.pdf

Newer version of manual:

www.mikrocontroller.net/attachment/164956/ttester_eng104k.pdf

It was find a birthday present for one of my Amateur friends, well he is going to be 70 in a few weeks, so it was time to look for something useful or interesting.  A bottle of Scotch maybe or a woolly hat? Then I had a thought he owns a Yaesu FT-897, and I had seen the Chinese selling external meters on ebay for this radio. There are two versions available, white backed scale, or black versions. I decided to take the risk and send for one in black, will it arrive here before his birthday? It did! It was delivered in less than 10 days from HK, although the sellers address was Shenzhen China?

The analogue meter replicates everything you see on the digital bargraph meter on the front of the FT-857/897 (S, PWR, SWR & ALC)

First thoughts not bad, quite weighty, excellent black anodised metal case, with a 3.5mm jack to plug into the external meter socket under the VFO knob on the front of the FT-897, or the left handside bottom front ext meter skt of the FT-857. It was time to take the roof off and have a look inside, well I did want to make sure it was ok for him?





There is plenty documented on the Web about making an external meter for these radios and really there is not much to it. But the Chinese have really made a very good job of this for the money, its not just a meter stuck in a box, they have taken their time to produce a little PCB with the calibration pot which can  be easily accessed from the rear of the case through a small hole. The PCB has then been bolted across the two rear meter terminals and it is a real solid job.




There were no instructions in the box that it came in, but these are well documented at the bottom of the ebay sales literature, and reference to all of this is set out within the Yaesu manual.

Conclusion: Well made and produced for the cost, you would find it very difficult to get all the bits together including the case and build it for the price. I wasn't able to test it out as I don't own either radio, time to wrap it up and put some kisses on the birthday card.

Reference:

http://www.ebay.com/itm/New-External-S-meter-SWR-Power-meter-for-Yaesu-FT-857-FT-897-Black-/121480229454?

Delivery came quick! I ordered the meter at the end of the festive period from Banggood on the 29th December 2014, it just took 16 days to arrive to my home in the UK. It came well packaged, surrounded by plenty of polystyrene wrapping and housed in a sturdy polystyrene box, which does show signs of plenty of bashing through its travelling trip on route from Singapore.

For the cost of £20 ($30 US) it looks and feels like a more expensive meter, but do looks deceive?

The movement is good, you can tell this by moving it from left to right and noting that it is well damped and returns slowly to it zero position, the range selector knobs and switching has a professional feel and click into position.



The manual isn't up to much, as 99% of it is written in Chinese. I am able to decipher that it is an Industry standard 20'000 Ohms/V meter on DC +/- 2.5% , except 2500V @ 4000 Ohm/V.  On AC ranges it is 2500 Ohms/V +/- 5% accuracy.  DC Current (I) is +/- 2.5% & AC Current +/- 5%.
Ohms measurement +/- 2.5% accuracy.

Batteries required for Ohms ranges are a 9V PP3(6F23), and one C cell, although an AA will fit to get you away.


I was excited like a little boy with a new toy to get the back cover open to give it a good looking over. Turning it upside down onto its face, are 4 sturdy anodised screws that are covered over by plastic plugs in each corner of the case, these easily pop out with small screwdriver forcing them up.

The rear cover then splits away in half, leaving the wires attached from the battery box to the main PCB. I was slightly disappointed by its SMT design, but I accept most things are done this way these days. The odd leaded capacitor and resistor tagged onto the rear of the board did remind me of designs of past years, switching is direct onto the gold plating onto the board. The PCB looks good, there were no signs of any dry joints, however I could not see any fuses for protection, nothing is highlighted in the schematic, what could one really expect for the money? Prehaps I am just used  to my ageing AVO 8 with its popout safety breaker.



If you note from the specification the meter does cover 2.5KV! However, I would certainly not like to be on the end of it with the test probes provided (two pairs included), my BIC biro has more plastic on its case than these suicidal leads that are certainly not up to the job!  A purchase of a good pair of leads to CAT III spec is a must!




Conclusion so far:  Sturdy well made case, Meter movement has the looks and feel of a professional movement costing 10 times more. If you are a novice coming into the hobby and you can't read Chinese don't blame me if you can't understand the manual how to drive it? Anyone else who has been part of the hobby game or the field should have no problem sorting it out. May not be serviceable if you blow or damage parts on the board if you select and use it on the wrong range? Requires a decent set of test leads and probes!   

Testing to be concluded further down the Blog.

Christmas came and went very quickly this year yet again. I must be getting old these days to feel that I don't enjoy it any longer? No sooner we had done the shopping and all the running around for ourselves and the family, stuffed the turkey, had a few visitors and done a bit of entertaining, we were left with nothing more than a few bones and an empty fridge.

The last of the turkey went in the pot a few days ago and we boiled it up for a nice stew, this was really appreciated as the weather had turned colder here since Boxing day the 26th, we even had some snow! After the stew followed a nice piece of homemade Xmas Cake and a large Scotch keeping one in the spirit of things.




Presents were few this year, I cheekily had asked for the money on purpose because I would like a new wristwatch, when the one I have been looking at for quite sometime comes around in a sale in the New Year at the right price.

However, apart from the analogue meter which I have already purchased from the gift cash pot: (see: http://g1kqh.blogspot.co.uk/2014/12/spare-pocket-money.html ). I did receive a couple of other nice little presents too. A book from the RSGB by Eamon Skelton & Elaine Richards. Building a Transceiver http://www.rsgbshop.org/acatalog/Online_Catalogue_Technical_6.html  (I currently do not have permission from the RSGB to reproduce or copy, so I cannot provide a photo of the front cover, hence the link. I am working on this one!).

My other tech present was a nice little DMM in the shape of a probe from Mastech Model MS8211:








First thoughts about this, it comes in a sturdy box with instructions and a certificate, complete with a nice case, a couple of leads for the Com, one with a probe and the other with a croc clip attached. The whole unit has got a nice rugged feel about it.

I am looking forward to reviewing the DMM along with the book further down the Blog.


A Happy New Year to you all!

LNR Precision is now flagging a price of $575 (£380 UK) for its new HF QRP radio the LD-5. I guess this price doesn't include shipping?

Currently it is flagged "Out of stock".

http://www.lnrprecision.com/store/#!/LD-5/p/39885476/category=10468544

I gave a short mention about this radio back in October:

http://g1kqh.blogspot.co.uk/2014/10/lnr-ld-5-no-news-is-good-news.html

Plus a link to its manual a few weeks later:

http://g1kqh.blogspot.co.uk/2014/10/lnr-publish-ld-5-manual.html

If I was buying this radio here in the UK, I would like to see it supported by a dealer, so I hope you all are reading?