I was chatting on the weekend with a new ham who was inspired by an article in Amateur Radio to build an OCF dipole using galvanised fence wire.
I have not seen the article, but he recalled that it recommended single core 1.25mm galvanised wire as quite suited to the task of an 80m OCF dipole. The wire consists of a mild steel core with a thin layer of zinc. Continue reading Galvanised steel wire OCF dipole
Following on from BLHeli on Hobbyking 40A ESC 4A UBEC 9261000003…
I was sent some further info on the bootloader firmware and adapter hardware.
Initial experiments using an adapter that I use for a range of this type of application were unsuccessful. On examining the waveforms with a ‘scope, it was apparent that a lower value of pull-up resistor was required. Continue reading BLHeli on Hobbyking 40A ESC 4A UBEC 9261000003 – #2
It is more than 10 years since I designed the PIK (PIC Iambic Keyer), a semi automatic Morse keyer (Duffy 2000).
This article looks at the operation of the auto-space feature of PIK. Continue reading PIK and auto-space
The recent release 11.2 of BLHeli supports some popular Atmel based ESCs.
This article is a review of HK_UBEC_40A_MULTI_REV11_2 on that ESC (http://www.hobbyking.com/hobbyking/s…arehouse_.html) at 4S with a Hobbyking 4822-690Kv 22 pole motor and 1045 SF propeller. This ESC was chosen as it is an inexpensive ESC that rates well in features (fast N FETs, support for bootloader and fully damped mode) in BLHelis documented compatibility list. Continue reading BLHeli on Hobbyking 40A ESC 4A UBEC 9261000003
VE7BQH publishes a table of Yagi performance data derived from a number of modelling programmes. The table is often used as a definitive reference of the overall merit of an antenna by buyers, makers and students for their own situation.
This article is mainly motivated at better understanding the G/T column of the tables. Continue reading Trying to make sense of the VE7BQH Yagi performance tables
A correspondent is designing a high performance transverter from 144MHz to 28MHz to be used with a Elecraft K3 transceiver.
A question that arises is just how good should the performance of the transverter be, what Noise Figure and Gain should it have without having performance that cannot be fully realised due to external noise. Continue reading High performance 144MHz transverter design workup – noise and gain analysis
A new Red Brick 70A ESC (including BEC) was received and checkout performed to select a SImonK module to load.
Continue reading SimonK ESC FW – test of commit 1f75da – #4
NFM has been updated to v1.18.0.
It includes for user convenience, a noise measurement uncertainty calculator based on the discussion of uncertainty of the noise sampling process at (Duffy 2007b) and the calculator at (Duffy 2007c)
Continue reading Update for NFM software (v1.18.0)
Folk often ask for instructions for assembly of so-called clamp type coax connectors.
This article shows such an N type connector, but the techniques are applicable to different connectors with the same type of cable / braid attachment. Continue reading Assembling clamp type coax connectors
COMP_PWM is an option on SimonK ESC firmware for sensorless brushless DC motors (Kirby 2011),
This article looks at the current waveforms resulting from that implementation, and is an expansion of (Duffy 2014).
Continue reading COMP_PWM and SimonK ESC firmware – part 2