rinioth: (radio)
The HF Packer Linear Amplifier is now complete, I did all the testing and setting of the bias levels yesterday.

This morning I added all the labels.





One thing I'm not too happy about is the paint, it seems that despite taking a lot of care with the preparation, priming and painting the finish is still not very durable. Even reasonably gentle handling has caused some flaking.
rinioth: (radio)


Other things have kept me from progress on the Packer, but I did finally get the construction complete today. Building all the internal interconnecting leads was very fiddly, partly because of all the small connectors that are needed.

The power supply board is on the top in the photos with the RF board underneath it. The Low pass filters are at one end and the external connections at the other.

That leaves the testing and adding legends for the controls and connections.

Note that the amplifier is upside down in the photos.

rinioth: (radio)
This is the Band Switch and the associated "Low Pass" filters.

Each of the six bands has a filter made from a pair of inductors built using the toroids and several capacitors. There are 13 coils and 26 capacitors in total. For the mathematically awake people who realise that doesn't quite add up, one of the bands has three coils rather than two. My fingers are now quite sore from winding all the coils.

I've done a trial fit in the case and have been able to work out where to fit the Tx indicator Led and the enable switch, so some more metal bashing is next on the agenda.
rinioth: (radio)

The Power supply board is now also finished. This is one of the more cunning parts of the design since it transforms the external nominal 12 volt supply into 24 volts for the two Power Mosfets that form the main amplifier stage. This actually makes them more efficient and also helps reduce distortion of the signal.

The next step is the output low-pass filter board.
rinioth: (radio)
More progress on the Linear Amplifier, the RF board is now complete. The construction manual could have been more clear, but I got there in the end.

Next job is the power supply board.

Weight loss

Apr. 3rd, 2016 04:06 pm
rinioth: (weeme)

A few days ago [livejournal.com profile] lastalda posted about weight loss, it made me realise that I'm getting quite close to my target weight too. I've been very slowly losing weight over the last 5 years, mostly by eating sensible sized portions and trying to get at least some exercise. I hadn't really thought of it as being on a diet but it obviously works for me and I do feel better for it.
rinioth: (radio)

A bit more progress with the chassis. This is a trial fit of the two main PCBs (there is a third one for the filter assembly). You can just see the Heat-sink under the chassis.

The front and back are next. Then I will start on the actual electronics interleaved with painting the chassis.
rinioth: (radio)
In a change from doing lots of electronics I've started building a kit I got at the local radio club surplus sale a few weeks ago. It's an "HF Packer" linear amplifier for my portable station.



There will be electronics involved, but the initial work is all cutting holes in the supplied aluminium chassis which forms the case.

The pcb on the left is the main RF board, it fits into the chassis on some short spacers. The main power Mosfets are bolted directly to the heatsink which goes underneath the chassis, hence the large holes which give clearance to the Mosfets and allow their leads to reach the pcb.

Next job is to drill and tap the heatsink, after that there are more holes to go in the front and back of the chassis for the controls etc.
rinioth: (weeme)
My eldest daughter and her family came to stay for a visit this weekend since it was my younger daughters 30th Birthday. We had some fun making the house 'Martha' proof and mostly succeeded. She is at the crawling and pulling herself up stage but can't quite walk yet even holding on to things.
She ignored her pile of toys and found it much more fun investigating other things.



It would seem from her interest in my technical books that she might turn out to be a computer geek like her father and Grandfather. Today we all went out to lunch and had a good time with much catching up.
rinioth: (weeme)
I spent Christmas with my two daughters and my granddaughter and son-in-law.

We had a good time, Martha had the most enormous pile of presents!

Since we were all having multiple gatherings we had decided not to have yet more turkey and so Christmas lunch was a Beef Wellington, cooked by Lisa my younger daughter.



It's pictured just after it came out of the oven while "resting". It was served with peas, carrots, parsnips and garlic and herb potatoes. After a suitable rest for us, we followed it with Christmas pudding.
rinioth: (weeme)
Martha is now 4 months old so here are a couple of new photos

Martha at 4 months

Martha at 4 months
rinioth: (radio)
You can never have too many Antennas so of course I've been working on another one. The current project is another EFHW (End Fed Half Wave) this time for the 80m (3.5MHz) band.
EFHW antennas have a high impedance at the feed-point and so need a matching transformer. The radio likes to see about 50 ohms so a transformer with a turns ratio of 3:24 gives an impedance ratio of the square of that, so 1:64 giving 3200 Ohms which matches the impedance of an end-fed antenna quite well. To fine tune the match a capacitor is needed across the secondary of the transformer, in my case a variable C in parallel with a fixed C to give the right range. I've built the hardware over the last few days and if the weather cooperates I'll install it later this week.

80m EFHW Transformer

The resistors across the output connections are a dummy antenna for setting the variable capacitor to approximately the right value.

Awards

Oct. 22nd, 2015 11:14 am
rinioth: (radio)
One of the typical things about hobbies is that they often have award schemes, Amateur Radio is no different. One of the most popular awards is the 'DXCC', the DX Century Club Award from the American Radio Relay League (the American National Society).

The lowest level of this award is for making a two way radio contact with at least 100 different 'entities', each entity is basically a country, there are currently 340 in existence (they change from time to time as the political world changes). Each contact has to be confirmed either by using the ARRL on-line logbook system or by the old fashioned method of exchanging 'QSL' cards which are postcard sized records of the contact often with photographs of the operator, his station or location.

Making contacts with 100 entities is not that difficult, getting all the confirmations can be harder especially for rare locations. I passed the 100 entities worked milestone about a year ago, but it has taken me until now to get to the 100 entities confirmed goal. This is partly due to the slow speed at which QSL cards travel around the world (there is a bureau system which keeps costs down but which means a card can take over a year to arrive) and partly due to many Hams not being interested in awards or in sending confirmations at all.

Since the ARRL charges for it's awards and it's cheaper if you use the on-line system, I've waited until I had 100 confirmed in the on-line system before applying. My certificate arrived last week and having found a suitable frame it's now displayed on my wall.



Currently, I have had contacts with 141 entities and have confirmations for 113.
rinioth: (weeme)
Martha is 5 weeks today and growing like a weed.

Martha at 5 weeks
rinioth: (weeme)
I'm a Grandfather for the first time!
My daughter Ruth has given birth to a daughter, Martha Jennifer.
Mother (and father) and baby all doing well.
More details when I have them.

Gardening!

Apr. 21st, 2015 03:10 pm
rinioth: (weeme)
Well, it's taken more than 3 years but I've finally sorted out the mess in the corners of my lawn. One corner originally had a small water feature, that has been gone for a couple of years but the space never got tidied up. Today I finally sorted that and another similar messy area. I've gone for minimum maintenance, in other words, turfed it!

rinioth: (radio)
Sunday morning started, after an extra hour in bed thanks to the clocks changing, as a repeat of Saturday with a nice breakfast and some socialising. Then it was time to check out, load the car and head off to activate another SOTA summit.
This time the plan was to activate Freeholds Top (G/SP-011). The plan was to park at the beginning of a farm track but when I arrived it was a building site compound of some sort, although deserted on a Sunday morning. There was, however, plenty of space to park on the wide grass verge and before long I was booted up and walking along the track. I'd decided on Wellies rather than walking boots because I knew the ground was going to be wet and almost the whole walk would be on the farm track or a moorland path. As I slowly gained height I began to feel the wind much more and once out on the ridge it was blowing a gale. The top looked like this:
freeholdstop
There is a small pond next to the trig point, but I didn't look any closer due to the wind. I decided to set up in the lee of the wall and soon had the mast and antenna up and the radio set up. Once again I was about 10 mins early on my alerted time but decided to call anyway. I was still calling with no response about 20 mins later and was wondering if there was a fault with the radio or antenna.
It turned out that there was indeed a fault, but not with my equipment, the ionosphere was broken! There had been an X2 class solar flare during the morning and it had wiped out HF radio propagation. Fortunately things recovered and I managed to work 10 contacts over the next 30 minutes starting with Bryan G4ZRP and signal reports slowly recovered to their normal levels.
I packed everything away and the wind seemed to have become even stronger. The sun came out and the walk back down the track to the car was actually quite pleasant once I was below the ridge line and thus mostly out of the full force of the wind.

Back in the car I headed for home, a long and rather boring drive but without anything much in the way of traffic delays, arriving home just before it got dark. Once unpacked and having relaxed a bit I treated myself to Chinese takeaway for dinner.
rinioth: (radio)
Friday evening was the GQRP Builathon, this years project was a novelty 40m Tx designed by Johnny, SM7UCZ, built 'ugly' style on a block of wood using drawing pins as the anchor points for the components, power output was 200mW. Fortunately the kits we were using had been translated from Swedish.
buildathon_sm
About 15 of the kits were built and all were working by the end of the evening.
The evening continued for some time with socialising, and food and drink being available.

Saturday morning after a good breakfast I headed over to Rishworth School for the actual rally event. There was a good crowd present and all the tables in the hall had been rented out to traders so there was lots on offer. I bought a few bits I needed but managed to come away without any 'surprise' purchases. As well as the traders there was a lecture program and I went along to hear Richard G3CWI give us an interesting talk about portable operating including some stories about his experiences operating portable around the world in exotic locations often as the result of work trips. After another walk around the traders area and some more socialising I decided to head back to Halifax and spend the remainder of the afternoon doing some Geocaching along the canal. Found one cache and failed to find another while enjoying a couple of miles walking beside the canal.
Saturday evening was spent with many of the same people in the nearby pub having a meal followed by more socialising (and more food and more drink) back at the hotel.
rinioth: (radio)
This weekend was the GQRP Club rally weekend. It was held partly in Halifax and partly in Rishworth a few miles to the west.
I decided that such a long journey needed to be "worthwhile" and so I planned some allied activities around the rally and associated social activities.
Friday morning found me with the car packed and headed up the A1 and M62 to Yorkshire. A brief stop for lunch just before leaving the A1 had me fortified for my planned SOTA activation of Hail Storm Hill (G/SP-009). I'd planned my parking place to be reasonably close to my planned activation point. What I hadn't quite realised was that the short walk was a lot steeper than I'm used to around Cambridge. So 45mins and a lot of effort later this was my view.
As you can see it was a bit damp on the moor.
hailstormhill
I set up the antenna and radio so that I could use the small horseshoe shaped stone shelter visible in the foreground to keep the wind off. I was ready about 15 minutes before my announced activation time but put out a call anyway and Rick came more or less straight back to me. Another 20 contacts followed in under an hour of operating before cold hands made me decide to stop.
With everything packed back into my rucksack I started down and it actually took longer than the ascent due to the need to be very careful on the slippery surface.
Once back at the car I was soon on my way to the hotel and half an hour later I'd checked in and was enjoying a long hot shower ...
rinioth: (radio)
I spent the weekend at the Radio Society of Great Britain (RSGB) conference at Kents Hill conference centre near Milton Keynes. It's a bigger and nicer venue than the one they have used in previous years with more accommodation and nicer, bigger lecture rooms.

I managed to attend 8 talks out of a possible 12 from the 5 streams. Lots of very interesting subjects and at times a very difficult choice between streams. There was a semi-formal dinner on Saturday evening, the company, food and drink were good and the after dinner speaker was excellent. Several manufacturers were represented at the conference and Martin Lynch had a trade stand there since they were major sponsors of the conference.

The only downside to the weekend was hearing of the sudden death back in August of an old friend from the Worthing Radio Club where I first got interested in ham radio.

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