Category: Miscellaneous

SiK is an inexpensive data radio commonly used by UAVs.

At least two of the ‘ground station’ applications incorporate facility for firmware upgrade, but if you aren’t using them for their main purpose, it is a huge installation just to upgrade the SiK radio.

Above is an inexpensive C2 programmer with DIY pogo pin adapter, one of may options. A C2 programmer is needed to write the bootloader.

The SiK radio project publishes a python script at https://github.com/ArduPilot/SiK/blob/master/Firmware/tools/uploader.py . This article gives a revised version that works on a HM-TRP radio under Windows 11.

The firmware was v2.2 sourced from https://firmware.ardupilot.org/SiK/stable/ .

Here is the revised Python script: Continue reading Stand alone update of SiK radio firmware

I purchased a Holzforma G395XP chainsaw, it is a Chinese clone of the now discontinued Husqvarna 395XP It is a relatively old technology carburetted engine without stratified intake and without introducing electronic auto tune, a 30 year old design.

Some of the fasteners used to hold the top cowl down were noodled and would only work with a plain slotted screwdriver. They were replaced with hex button head screws.

In the light of experience with Holzforma / Farmertec G372XT chainsaw – early evaluation, a decision was made to preemptively vacuum and pressure test the G395XP saw.

It failed the vacuum test, not really badly, bad badly enough to warrant repair. Continue reading Holzforma / Farmertec G395XP chainsaw – first impressions

I have a Toro ride on mower (riding mower in North America) which I ran out of fuel when it was quite new (<1y) and having put 5l of fuel in the tank, it would not start after quite a bit of cranking.

In this instance, the battery failed. Prolonged cranking can buckle battery plates, or open intercell connecting links, and although this was prolonged cranking, it was not ridiculously long. Perhaps the battery was the real cause of the failure?

Nevertheless, I asked what I could do to prevent this recurring. Continue reading Toro ride-on mower fuel system blues

This is a record of the internals of a SX25 top handle or arborist chainsaw purchased for about $100 on eBay, and used for about 50h for home yard maintenance.

I have owned three of these. Continue reading SX25 chainsaw (G2500 clone) internal pics after 50h runtime

I have a pressure washer with a 210cc Chonda GX200 clone that is very difficult to start. This article walks through the resolution.

Above is the equipment, it has less than 4h running time, so it is not ‘run-in’ yet, these type of engines improve up to 20-50h. Continue reading Difficulty starting a GX200 clone

I purchased a Holzforma G372XT chainsaw, it is a Chinese clone of the now discontinued Husqvarna 372XP X-TORQ. It is a relatively new technology carburetted engine without introducing electronic auto tune, a 20 year old design.

There are plenty of online discussions about the 372XP X-TORQ overheating, hot seizures, and pics of blued big ends, scored pistons and bores etc, so whilst the design achieves quite high power output for 71cc, one is warned to pay attention to mixture, fuel quality, and lubrication. This might be an engine that should not be used with other than full synthetic two stroke oil. Continue reading Holzforma / Farmertec G372XT chainsaw – early evaluation

A really important test of two stroke engines is the crankcase vacuum and pressure test, as air leaks through crankshaft seals, intake boot, cylinder gasket, decompression valve, impulse tubes etc can cause them to run lean leading to premature failure of the engine.

To perform a vacuum and pressure test of the Husqvarna 372 XP X-TORQ chainsaw engine, the intake needs to be blocked off, and the exhaust blocked off, and the test can be performed using the impulse hose.

The intake boot in the Husqvarna 372 XP X-TORQ has a rubber tongue that projects into slots in the carburettor throat, part of the strato engine.

Above, Husqvarna 578-09-56-01 intake block off adapter for the Husqvarna 372 XP X-TORQ. The open end of the ‘tube’ mates with the rubber intake boot, and the recess accommodates the tongue mentioned. Continue reading An improvised intake block off adapter for the Husqvarna 372 XP X-TORQ etc

Some radiosonde signals are successfully decoded at distances well in excess of the specified range for the radiosonde.

Experience reported here relates to Vaisala RS41-SGM radiosondes which are specified at 60mW max transmitter output and range up to 350km.

Free space model of the radio path

Whilst the path is over land, the radio path at high altitudes approaches a free space path, albeit with some ground reflection effects at the receiver.

The transmit antenna is probably close to a vertical dipole in performance, lets assume that it has a gain of 2.13dBi in the path direction.

Receive antennas will commonly be omni directional, and fairly low directivity, so lets just assume rx antenna system gain 0dBi.

If the path was free space, the rx field strength would be 13.8dBµV/m, tx power -115.5dBm. This model ignores ground reflection gain and losses, but it is in the ball park. Continue reading Radiosonde propagation – is aircraft enhancement significant?

I purchased two of these Irwin folding utility knives, they seemed like a clever design that addressed the failures of every other folding ‘Stanley blade’ knife I have owned.

Above is the Irwin knife, the blade is secured by a dog on the button shown at top, and the button is blocked from being depressed except when the knife is folded at 45° as shown. Continue reading Unjamming your Irwin folding utility knife

I purchased a Holzforma G395 chainsaw for $410 delivered but without bar and chain. It is a Chinese clone of the now discontinued Husqvarna 395XP It is a relatively old technology carburetted engine, prior to the strato technology (stratified scavenging) of the X-TORQ etc.

The Holzforma G395 has slightly lower published power rating than Husqvarna 395XP.

Previous experience documented at Holzforma / Farmertec G372XT chainsaw – initial evaluation shaped the approach with this one. Continue reading Holzforma / Farmertec G395XP chainsaw – initial evaluation