During the weekly F-troop there are mentions of software, websites and solutions that are worth taking note of. This website attempts to document them.

20190511 - Zebra Factoid

posted May 17, 2019, 5:00 PM by Onno Benschop   [ updated May 17, 2019, 5:01 PM ]

Elsa [VK6FZEB - preferred call], shares with us:

Did you know that zebras eat the tough grass at the top of the stem and leave the soft grass for other animals. Very considerate.


20190511 - C4FM

posted May 17, 2019, 4:58 PM by Onno Benschop   [ updated May 17, 2019, 5:04 PM ]

During the 'net one amateur asked about what C4FM was. Charles NK8O sent this information:

Here is a small write-up https://www.on0dp.be/?page_id=266.

It is essentially Yaesu’s proprietary digital mode, used in the Yaesu Fusion digital voice mode.

Interesting fact: once the signal is digitized into a stream, the format is identical to Digital Mobile Radio streams, and at that level they are compatible.  But the signal analog to digital encoding is handled very differently, and therefore the two formats are not directly compatible.

#c4fm #nk8o

20190511 - WWFF / Parks on the Air

posted May 10, 2019, 5:27 PM by Onno Benschop

Charles NK8O has been working on getting into World Wide Flora and Fauna:

20190511 - Build Projects

posted May 10, 2019, 5:24 PM by Onno Benschop   [ updated May 10, 2019, 5:24 PM ]

Charles NK8O has been building:

Powerpole distribution boards and QCX build #7.  The silicone pad is good for working on things because it won’t melt under solder or the iron.

#nk80 #QCX #build

20190504 - Build Projects

posted May 3, 2019, 6:10 PM by Onno Benschop

Charles NK8O shares with us a few build project photos:

These are the Cricket transceivers from 4-State QRP.  Note the built-in coils.

Ameco valve transmitter. The decals are incomplete because let’s just say it’s not my strong suit.

The entrepreneur lives in the US but he is Bulgarian, and obtaining the parts in Russia.

#nk8o #ameco #cricket #4-state-qrp #build

20190504 - Zebra Factoid

posted May 3, 2019, 6:04 PM by Onno Benschop

Elsa [VK6FZEB - preferred call], shares with us:

Did you know that a zebra can run at 64 km per hour.


20190427 - Inductance Measurement

posted Apr 27, 2019, 6:39 PM by Onno Benschop   [ updated Apr 27, 2019, 6:41 PM ]

Denis VK6AKR shares this information on how to measure inductance:
  1. Direct and simple, use an inductance meter, usually combined capacitance / inductance meters since they both typically measure reactance and often ratiometrically so that even the cheap and cheerfuls can give good results when calibrated against a known capacitance / inductance value in the range of interest. Disadvantage is that inductor Q is not measured. Laboratory grade instruments are available, think $$$$, that do assess Q factor.
  2. Grid dip meter method. Create a parallel tuned circuit comprising the inductor under test and a known capacitance, or just the inductor alone if some idea of its self capacitance is known (rare I would say.) If using an external capacitor the external cap value should be large enough to swamp out any self capacitance. E.g. multi-layer winding and / or close turn spacing would have higher self capacitance than single layer and / or widely spaced turns. Use the frequency displayed on the dip meter and the known capacitance value to work out the inductance. Q can be estimated - check the width and depth of the dip - but relies on calibration of the dip meter and accuracy of capacitor.
  3. Series resonance method. Needs accurate capacitor and frequency source. Connect a series string of resistor, known capacitor and unknown inductor across the signal generator output. Inductor connected to ground. Measure the resonance as a dip in signal at the junction of the resistor and the capacitor. Advantage, the signal strength detector loading does not affect the resonance point. Calculate inductance from the known frequency and known capacitance. Value of the series resistor not critical, could be in the range 470 ohms to several thousand ohms. Depends on the (resistive) loading effects of the signal detector which might be an RF voltmeter or oscilloscope or SDR. If using SDR be mindful of their typical 50- to 75-ohm input impedance in which case the series resistor might need to be lowered in value. Same comments apply to external cap value as for method 2 - if high self capacitance in the inductor, that will cloud the results for low external capacitance values.
In general, accurate frequency counters would be more available (economical) than accurate signal sources so the combo of a good freq counter and so-so signal generator will achieve good results for method 3. A freq counter could be coupled to a grid dip meter coil but would need to be very sensitive as most gdo's have very low radiation.

#vk6akr #inductance #education #methods

20190427 - Bridge Rectifier

posted Apr 27, 2019, 6:37 PM by Onno Benschop   [ updated Apr 27, 2019, 6:41 PM ]

Charles NK8O shares this information:

Here is my schematic for placing a bridge rectifier on a 7 lug terminal strip.  I have the parts purchased and ready to go into an aluminium box, with the transformer on top.  B+ output will be 300v DC with a 6.3 VAC filament output.  If you follow right down the middle of the schematic, you can visualize the seven pin strip.  It was more of an exercise in visualizing parts layout than PS design.  This is a pretty standard layout.  B+ #2 will have a voltage drop that is dependent on the plate current in the device.  At 20 ma it *should* show a drop of just a little less than 15v, and at 40 ma, the drop will be around 50v.  Case will have earth ground on a GFI protected mains that only allows 4-5 ma of leakage before tripping off.

Bridge Rectifier

Device values:
  • Switching diodes with PIV (peak inverse voltage) 1000v.
  • Electrolytics 20 mfd
  • Transformer 115 VAC input, 300 volts (center tap unused)
  • Resistors: 33K, one for voltage drop the other as a bleeder
#nk80 #homebrew #plan

20190427 - Bluetooth Question

posted Apr 27, 2019, 6:34 PM by Onno Benschop

Stephen VK2FCVD sends in this query:

I am looking for info on how to configure HC-05 Bluetooth module to 57600baud
I have found this info but not sure on how to go about it
Stephen Ford VK2FCVD 73s
Add Bluetooth Module To Your MINI60 HF Antenna Analyser

A while ago I purchased a "MINI60 HF Antenna Analyser" from Ebay to test some home-made antennas. I was disapointed to find it did not have the bluetooth module installed as I had seen on other MINI60 units I have used. The seller was adamant I was too stupid to notice his product excluded the bluetooth functionality that it should have, and it was just too bad for me... He got appropriate feedback ;-)

I decided to purchase a HC-05 bluetooth module from a local supplier, configured it to 57600baud but the original MINI60.apk android app won't detect the MINI60 device paired by bluetooth. It appears the developer of the original MINI60.apk app hard-coded it to work with only 4 specific MAC addresses - to suit only the bluetooth modules they supplied of course and they say the MINI60 also needs a firmware update to use the bluetooth module. This is lies! Any SARK-100 or MINI60 firmware will work with bluetooth.

After a bit of digging I found others had the same issue and a clever person has redesigned the MINI60 android app to work with all bluetooth MAC addresses so any HC-05 (or possiobly HC-06) bluetooth module will work. Also this modified app scales to the screen size better so the bottom line of frequencies is not chopped off.


These basic instructions will work for the MINI60, or any other SARK-100 clone
    1. Get a HC-05 bluetooth module and configure it for 57600 baud to suit the MINI60 PSoC UART speed

      Other defaults should be OK but you can name the bluetooth module if you want to. The original bluetooth module was called "MINI60 ANT". Check out the HC-06 data sheet on what "AT" commands are required.
  1. Solder bluetooth module into the MINI60 using the 5 small solder pads
  2. Use Bluetooth on your Android device to pair the MINI60. Default HC-05 pairing password will be 1234
  3. Copy the MINI60-DH1KLM app to your Android device storage and install it. Uninstall the original MINI60 app if you had it installed because it is useless.
  4. Turn on the MINI60 and enable PCLINK using the usual SET & DOWN buttons so it says "Waiting Link''' on the screen
  5. Start the MINI60-DH1KLM app, tap "Connect" and select your bluetooth module in the app
  6. Done!
#antenna #analyser #vk2fcvd #bluetooth #helpme

20190427 - Zebra Factoid

posted Apr 26, 2019, 6:00 PM by Onno Benschop

Elsa [VK6FZEB - preferred call], shares with us:

Did you know that a zebra isn't strong enough to carry humans and if you ever see a zebra in a movie being ridden, it's a painted horse.


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