Co-phased collinear for 2m – discussion of phasing devices

An exploration of a cophased collinear array with coax phasing stubs explored various structures for encouraging co-phase operation of a 3/4λ vertical over perfectly conducting earth (PCE).

This article expands that set with NEC-4.2 models of some variations on the traditional Franklin form of the antenna.

Let’s start with review of the traditional Franklin form

Franklin form

The graphic above shows the topology of the Franklin form. It comprises a half wave vertical element over a quarter wave element, with a quarter wave horizontal s/c stub as the device to encourage co-phased operation of the elements. The current magnitude and phase distribution is shown in green. Continue reading Co-phased collinear for 2m – discussion of phasing devices

Arduino SAMD21 bootloader protection II

At IoT – exploration of LoRaWAN – part 2 I reported some quality issues with two low cost SAMD21 Arduino Zero like boards, and at Arduino SAMD21 bootloader protection some related discussion.

In view of continuing experience of incorrectly programmed low cost SAMD21 boards, I have decided to re-flash them as a matter of course

Above is one of the culprit boards. Continue reading Arduino SAMD21 bootloader protection II

Motorola TAD1000B Folded Coaxial Antenna – discussion

This article is a discussion about the Motorola TAD1000B Folded Coaxial Antenna series.

Above is an image from Moto’s documentation, it shows what appears to be a simple coaxial or sleeve dipole, bit with the top quarter wave element folded like half of a folded dipole. Continue reading Motorola TAD1000B Folded Coaxial Antenna – discussion

An explanation of W5DXP’s ‘line extender device’

A correspondent wrote seeking explanation of W5DXP’s no-tuner tuner which purports to obtain a near match by adjusting the length of the transmission line using relays or switches of some kind.

The particular device that is of interest is one using a single double pole knife switch as a three position On-Off-On switch.

The accompanying explanations states that this “is a way to use a single DPDT knife switch to obtain one, two, or three feet of ladder-line depending on the position of the switch”. Continue reading An explanation of W5DXP’s ‘line extender device’

Rigexpert’s Antscope takes a bigger step backwards

At Rigexpert’s Antscope takes a step backwards I wrote of Rigexpert’s determination to cripple Antscope by reducing the maximum value of R and X on graph axes to +/- 1600Ω.

I have deferred trying the new Antscope2 until now to allow it to reach some maturity.

This article is a brief review of Antscope2 v1.0.10, brevity driven by the need to cut losses and run.

The first thing I noted is the difficulty in reading some textual data due to low contrast. The mid blue on mid grey above is very hard to read and would be even harder outdoors if measurements were being made in that environment. I did not search for alternative themes, none jumped out, but out of the box, this is very limiting. FAIL. Continue reading Rigexpert’s Antscope takes a bigger step backwards

AIM 915a produces internally inconsistent results

 

AIMuhf

AIM915 was recently pulled from the distribution site and replaced by a new release, AIM915a.

I cannot recall ever finding a new release that did not have significant defects, commonly inconsistency between displayed values. In the common theme of one step forward, two steps backwards, this version has defects that were not present in AIM910B.

This problem existed in AIM915, it persists in AIM915a.

Let’s review the internal consistency of this part of the display screen.

Most of the values given above are calculated from a single measurement value, and should be internally consistent. That measurement value is translated to different quantities, many based on the stated Zref (50Ω in this case). Continue reading AIM 915a produces internally inconsistent results

Arduino SAMD21 bootloader protection

At IoT – exploration of LoRaWAN – part 2 I reported some quality issues with two low cost SAMD21 Arduino Zero like boards.

In both cases, the bootloader did not work. I did not investigate further but did note that the NVM user row looked like it had been cleared, but just wrote a new bootloader and restored a default user row with protection for the 8192 length bootloader.

Above is one of the culprit boards. Continue reading Arduino SAMD21 bootloader protection

IoT – exploration of LoRaWAN – part 2

At IoT – exploration of LoRaWAN – part 1 details were given of first steps in a LoRaWAN project.

This article documents some MCU boards used for prototyping solutions.

The Arduino Zero concept was chosen for a modern module supported by the Arduino IDE and with ample memory resources for the LoRaWAN protocol stack and application code and memory requirements.

The boards tested are ‘basic’ Zero boards using the Atmel SAMD21G18 MCU. None of the three boards discussed here had the ‘PRO’ EDBG chip / ‘Programming USB’ port, they had only the ‘Native USB’ port.

Wemos SAMD21 Arduino form

Above is the module under test. Continue reading IoT – exploration of LoRaWAN – part 2

Dragino LG02 review

This article reviews the Dragino LG02 LoRa ‘gateway’.

Above is a pic of the supplied device, and notably it is supplied without the external WiFi antenna shown in the manufacturer’s literature and seller’s web shop.

Above is a close up of the case with the plastic plug removed from the ANT-3 hole, there is not connector, the device does not have provision to install the external WiFi antenna and presumably has an internal antenna though we might expect that has reduced range. Continue reading Dragino LG02 review