Cheap Chinese wristwatch #1

I bought an inexpensive Chinese manual wind wristwatch for my grandson. It is a skeleton style watch based on the communist Tongji movement.

Above, the watch looking pretty flashy in gold coloured finish. The gold plate wore off the band in just a few days to reveal a brass band tarnishing by the hour. The bezel is probably base metal and will corrode in no time. Continue reading Cheap Chinese wristwatch #1

Ham grade analysers and VNAs often use unconventional meanings for well known terms

Lets use a simple test circuit to review the meaning of some oft misused terms associated with VNA and antenna analyser measurements.

Above, the test circuit is a nominally 220pF COG capacitor connected between tx and rx ports of a two port VNA. An extra 1Ω series resistance is included to model the likely effect of capacitor ESR. Continue reading Ham grade analysers and VNAs often use unconventional meanings for well known terms

Mandarin & Lime Marmalade

I couldn’t help myself, Mandarins are falling and I had to try a marmalade of Mandarins and Limes. I made a small batch of marmalade using 50% Tahitian Lime and 50% Imperial Mandarin. Raw sugar was one third the added sugar to impart a darker colour.

MandarinLimeMarmalade

The marmalade is light coloured, sweet and tangy. Continue reading Mandarin & Lime Marmalade

Tahitian Lime Marmalade

We had a small excess of Tahitian Limes ripen, so I tried a test batch of Tahitian Lime Marmalade.

TahitianLimeMarmalade

The marmalade is light coloured, sweet and tangy.

The downside is that the fruit is full of seeds, not just in the equatorial plane but distributed right through it, so scooping seeds out is quite a task.

Screenshot - 26_07_16 , 10_37_42

 

It is the first time I have made jam from these, and essentially I used the 40:60 mix from FAO’s Generic Jam Recipe, though being limes no acid was needed, in fact about 6g of Sodium Bicarbonate per kg of fruit to achieve the ideal pH of 3.2-3.3. The limes were cooked to release some Pectin, but a little Pectin 10g/kg) was added as the cooked fruit gave a slightly weak reaction in Methylated Spirits.

Endpoint was assessed by measuring Brix using a refractometer, confirmed by setting a drop of jam on a cold plate.

Australian Lime Marmalade

Winter has arrived, but so has the citrus fruit matured.

I picked a bucket of Australian Limes which had ripened to the point of mostly yellow skin.

AustralianLimeMarmalade

Being a bit partial to Lime Marmalade, I have cooked up a couple of 4kg batches of high fruit content marmalade and bottled it.

Screenshot - 04_06_16 , 14_55_44

It is the first time I have made jam from these, and essentially I used the 45:55 mix from FAO’s Generic Jam Recipe, though being limes no acid was needed, in fact about 2.5g of Sodium Bicarbonate per kg of fruit to achieve the ideal pH of 3.2-3.3. The limes were cooked to release some Pectin, but a little Pectin 6g/kg) was added as the cooked fruit gave a slightly weak reaction in Methylated Spirits.

Endpoint was assessed by weighing the pot from time to time until the jam had cooked down to the target 4kg of product.

The old wheelbarrow will not die

We bought a cheap wheelbarrow 6 years ago, and it is like grandfather’s axe: 6 new handles and 3 new heads and its 100 years old.

This thing has had numerous tyre patches (some due to defects in the cheap Chines tubes), three new tubes, two new tyres, it is trying to rust out, and the concreters working here last Winter used it to carry fully loads of concrete… splitting the side of the poly tray. The split has been growing slowly with temperature cycling, I should have drilled some small holes to defuse the stress raiser at the ends of the split.

IMG_0539

Whilst I have replaced the barrow, we continue to use this one to exhaustion… and I succumbed and plastic welded the split in the tub. A similar bead on the inside dressed with a burr to remove edged that would catch on tools compete the job… we will se how long it lasts.

Red Ironbark picnic table

I made a couple of picnic tables about 35 years ago. The design was broadly inspired by picnic tables deployed by the ACT administration at the time (local government), it used a galvanised water pipe frame for table and integral seats and hardwood tops.

IMG_0484a

I kept one of these tables, and the hardwood eventually degraded sufficiently to warrant replacement.

Durable timber has become very expensive, and the choice limited. Red Ironbark (a eucalypt endemic to the forests south east of here), GOS (green off saw) and DAR (dressed all round) was chosen, and stacked in the shed for a couple of years to dry down to 10% moisture content.

The timber was washed down, trimmed and edged, drilled and oiled (Organoil, a naturally drying oil mix), and fixed to the table with 304 stainless countersunk socket head M8 screws and nyloc nuts.

PicnicTable

Above, the refurbished table. Total mass is 125kg, about half of that is in the hardwood and the rest in the steel frame.

The table will required replenishment of the oil finish every year, but should be a durable non-toxic lasting finish with that maintenance.