Tag Archives: bluetooth

miniVNA and Choke Measurements

I recently bought a miniVNA Pro analyzer:


This is a pretty cool little device that goes beyond just analyzing antennas. One of the first tasks I set this to was measuring some ferrite chokes for comparison. The miniVNA makes quick work of this in transmission mode and in saving the data in Excel format. Here are choking impedance plots for three ferrite based chokes:


In blue is 9 turns of RG-8X around two FT240-43 cores. This has the best choking performance. The orange plot is a 1:1 choke balun made from an ebay kit. The grey plot is an MFJ-915 line isolator.


Mini60 Bluetooth Progress – Nothing is Ever Easy!

I soldered the bluetooth module onto the Mini60 at the five solder pads. At this point I installed the battery and shorted across the switch terminals to test ot. The Mini60 comes up ok and I can place it into PC Link mode but the module is not powered up. Turns out there is is no 3.3V coming in at the pad I soldered it to. I have removed the module and rechecked the voltage and there is no power. Sigh…

There is not schematic or PCB layout for the Mini60 but it is very close to the SARK100. I found 3.3V coming out of the USB chip but have not found how its piped to the second PCB. So work has stalled and I’ll have to check all the required signals by tracing manually.

Update 5/16/17: Ok I think I found the problem. There are three pads that need to have jumpers installed to connect the top board to the bottom board. These three pads bring in the UART RX and TX signals and the 3.3V to the pads where the Bluetooth module is installed. Will solder the module back in place and test later today. The instructions at http://www.die-jetzis.de/bt_install.htm indicated only two pads. Looks like there are several variations of this board. I have noted that several folks have reported issues with theĀ  Bluetooth module not responding. This is the likely cause as it is not clearly documented. Here is the board and the three pads are just left of the BT module:

Photo May 16, 9 34 26 AM

Disassembly of the Mini60 Antenna Analyzer

Opening up the Mini60 Antenna analyzer is fairly straightforward. Fours screws on the side remove the back cover. This will expose the battery which can be removed easily by disconnecting the molex connector.

Photo May 14, 2 13 21 PM

The circuit board needs to be removed completely which requires the power switch and coax connector to be desoldered from the board. Desoldering tools and braid are highly recommended. Remove the four corner machine screws and the board should come out. Flip the board over and you will see the silk screened area where the bluetooth module is soldered.

Photo May 14, 2 41 11 PM

Surgery on the Mini60 Begins…

I started the bluetooth module retrofit of the Mini60 Antenna Analyzer today. First step is to configure the BC04-B Bluetooth module as the only baud rate supported is 57600. To do this I needed to buy a USB to TTL module from Ebay:


Instructions for programming the new baud rate and wiring the module can be found here: http://www.die-jetzis.de/mini60_bluetooth.htm. The painful part is making the connections to the USB to TTL converter. I had to solder four small solid wires to the necessary pads which is tricky as the pads are small and its hard to keep everything positioned. I needed a set of third hands, magnifiers and pair of tweezers but I got them on. The programming went as advertised. Once programmed I removed the wires and prepared to install on the Mini60.


Planning an upgrade to the Mini60 Antenna Analyzer

My posts on the Mini60 antenna analyzer remain the most popular views on this blog. I have not been using it much since I acquired a RigExpert AA-230 zoom. The RigExpert is so easy to use and provides a wealth of information when tuning antennas. That being said, I have not given up on the Mini60 as I intend to use it on Field Day.

I am going to be retro-fitting a bluetooth module to the Mini60 over the next few days. I need a USB to TTL adapter to program the bluetooth before installation and then wire it into the PCB. Worst case I end up trashing the mini60…best case I’ll have a wireless Android interface for this over bluetooth. Stay tuned as I’ll post some detail on how this proceeds.

Snagged a Netbook

I was going through a local pawn shop earlier this week and came across a Gateway LT4004u netbook that had just hit the floor a couple of days earlier. It turns out to be in great shape with 2GB ram (maxed out), 150GB drive and a decent set of USB and other ports. I have been wanting a netbook for its size and low power requirements to work HF portable digital modes. This little unit fit the bill perfectly and for $60 I could not go wrong. I have ordered a 12V to 19V converter so that I can use this with my solar generator. I re-installed Windows 7 on it and after hunting a bit was able to load all the orginall drivers. Only thing I plan to add to it at this time is a Bluetooth dongle so that I can control my FT-817ND with a bluetooth CAT gizmo I acquired some time ago. Battery life on this looks quite good so I’d say I lucked out.