MRM-30 goes QRO

 

One of my first Manhattan style construction projects was a RockMite 30 circuit. I had upgraded my RockMite 20 with a Hamgadgets memory keyer chip, this left me with a spare keyer chip. I thought a great way to use the spare chip was to build a RockMite 30. I had seen pictures of other home brew RockMites on the Internet and I thought it would be something I would be able to do.

 

I wanted to make an 'ultimate' RockMite, so I put in a VXO circuit and also the output PA transformer modification promoted on the Yahoo RockMite Group. I used a 2N3866 transistor for the PA. I was hoping for about 800mW of RF, but I was disappointed that the rig would only put out 520mW. I then upgraded the output filter, this promotes a super clean transmit signal from the rig, but it introduced another 20mW of loss, I was now only getting 500mW from 12 volts.

 

I was still pleased with my efforts though, it was the first home brew transceiver that I had attempted and it did work. My local radio club put on a camping and amateur radio weekend in July 2011 and I tried out the newly completed using an inverted vee dipole. I was pleased to work HB9UH with some very shaky QRS CW! It turns out that Hans, HB9UH, is a member of the Helvetia Telegraphy Club, a group dedicated to promoting the use and teaching of Morse Code.

 

The QSO with Hans remains my only contact with the rig. My CW has improved a bit since then, I have been using another Manhattan style RockMite 30 rig which I built to take part in LA1KHA's PP3 challenge and also an MTR by KD1JV for my SOTA activations this year. The MTR is my favourite rig, I rate it above everything else, so my other rigs have been gathering dust! I decided that I need to try to use my other home built radios.

 

I was always disappointed with the low power output from the home brew RockMite 30 - (MRM-30), I thought it would be more useful for SOTA if it could put out a bit more power. A couple of watts on 30m should be very useful.

 

I looked in to a design for a 5 Watt RockMite 80 on the Yahoo group, the design used a CB PA output transistor, a 2SC2166. I thought that I could use a similar scheme for my rig. I managed to locate an Eleflow 2SC2166 at a reasonable price on Ebay.

 

I replaced the 2N3866 output transistor on my rig with a 2N2222A and I used an adapted version of the 1.5W PA circuit from the Small Wonder Labs SW-30+. I knew that the circuit would be capable of a couple of watts at 10MHz. I built the circuit in to the RockMite this week and I was pleased to measure the output at around 2 watts, I'm well pleased with that! I could probably get a lot more out of the circuit, but I happy to stick at the 2 watt level. The signal still looks very clean, so I'm really happy.

 

I hope to try the rig from a SOTA summit soon, Winter Bonus is only a couple of weeks away!:-)

 

I haven't added any RX filtering yet, I'm going to see how bad it is without first!

 

New 2 watt output stage squeezed in (right hand, middle)

 



Buckden Pike - Remembrance Sunday

For this years Remembrance day, I decided to go to the Buckden Pike War Memorial to do the two minutes silence at 11am.

A Wellington bomber crashed on Buckden Pike in January 1942, killing all but one of it's crew. The survivor erected a memorial cross at the crash site to pay tribute to his fellow servicemen.

Buckden Pike, 2303ft, is classified as a 'Marilyn', so it is included in the SOTA scheme (G/NP-009), being worth 6 points. My plan was to operate my radio from near to the trig point and claim the SOTA points, before moving on to the War Memorial, something like 1km away.

I parked in the public car at Buckden and set off walking along the bridle path at about 0745utc. I was pleasantly surprised to find that the once boggy path had been properly surfaced and was now easy to walk on.

 

I gained the summit at just after 0900utc, it had taken around 80 minutes from the car park to the trig point, much faster than previous occasions.

 

 

I'd taken along my MTR (Mountain Topper), a little two band CW rig, built into an Altoids tin. Using a 1000mAh LiPo battery, I was on the air on 7.032MHz at about 0925utc with about 2.5W. I was amazed at the pile up that quickly developed! I found after about 20 minutes of operating, my brain got a bit fried and I started making a lot of mistakes. I took a 5 minute break from the pile up, but upon asking 'QRL?', I was greeted with another wall of chasers! I moved on to 14.058MHz, again I was met with a big pile up after only a few minutes. My time soon unfortunately run out, so after working Barry N1EU in Delmar, NY, at 1040utc, I had to leave the chasers and tear down the station. 34 QSO's were in the log, so the little MTR had done a great job, I'm sure I could have worked many more stations given a lot more time. I had actually operated a little too long really, it was 1050utc by the time I left for the memorial, and it was about 1km away!

 

 

Unfortunately, the route to the memorial is very boggy indeed! I simply didn't have the time to carefully pick my way through the bogs, I just had to run like mad! I reached the memorial at 1058utc, I'd just made it and I was quite soggy too! There was quite a mixed gathering of people at the memorial, and we all fell silent for two minutes at 11am. I was persuaded to pose for a group photograph, although I didn't know any of the other people there! For once, the photos should turn out OK, the weather was actually very nice, usually the visibility is very poor at that time of year, with thick fog being the normally expected conditions. My camera didn't record the memorial pictures properly, so I don't have any pictures of the people at the cross :-(

 

As you see, the weather was fantastic -

 

 

73 de Colin, M0CGH

 

 

Elecraft K1

I was delighted to be asked to build an Elecraft K1 on behalf of a fellow ham a few Month's ago.

The K1 kit had arrived within a few days of ordering direct from the USA. The kit came with a very comprehensive owners manual / builders guide. The K1 was ordered with a 2 band filter module (40/20), LCD back light kit and KAT1 auto ATU.

I was expecting a very high quality kit, and I wasn't disappointed!

First of all, the filter board was constructed. All went together fine, the instructions were very clear indeed.




Next came the front panel. The front panel is the main operations centre, it houses the main processor which controls of all the rig's functions. Components are fitted both to the front and back of the board. Again, the construction was very simple.

The instructions were really good. The front panel LCD backlight kit was also added at this time, it is much easier to do it this way than 'retro fitting' it I am reliably informed from multiple sources!

The main board is constructed last of all, this board contains the receive and transmit circuitry, the receive portion mostly towards the front of the board, whilst the transmit portion is mostly at the back. The RX and TX sections are built and tested in turn.

Left - the K1 main board with receive portion complete just after initial 'smoke test'. Luckily there was no smoke! The board fired up first time without problem and all the voltages checked out OK. The instruction book gives lots of testing opportunities, first of all you do resistance checks to make sure than there aren't any solder bridges etc.

Once you are happy with the resistance checks, you then go on to the voltage checks with power applied. Whilst in theory you could just build the whole K1 and do 'all up' testing, building and testing in small bits gives you confidence that you are doing everything right. It's a great feeling when all checks out OK.

The TX portion of the rig went together really well, the hardest part being the winding of the little transformers. I found it a bit tricky to get them to sit and look neat, but I got there in the end and I'm happy with the result.

The alignment of the rig is pretty simple, first you tweak the inductors on RX before completing the TX build, then after TX build you tweak them again on transmit.

I used the sound card on my laptop to set the BFO offset, although initially I had just done it by ear and the computer confirmed that I had got it pretty close. I found it quite amazing that I was using signals from the US to align the rig - 20m was very lively at the time, W1AW kindly confirmed calibration of the VFO readout on 14.0475 MHz :-)

 There are a few components fitted on the underneath side of the main PCB, I guess that Elecraft ran out of space to put them on the top. The rig uses all through-hole components, there are no SMDs used anywhere in the rig. The components all lie flat on the board too, this is not something I'm used to, the kits I've built recently have all used resistors and diodes in a vertical fashion, I use vertical mounting for my Manhattan rigs too, it just saves so much space.

I think Elecraft made a good decision spacing the board out the way they did, it makes construction easy, especially as all the footprints for the similar components are the same, this makes pre-forming the leads a piece of cake - well done Elecraft! (Note that some component locations are intentionally unused - I haven't missed them off by error!)

I think the assembled rig looks very nice, it certainly doesn't look as though somebody has put it together in an attic in Yorkshire! (yes, it was assembled in an attic in Yorkshire!)

There is a lot of work involved building a K1 - it has taken me a number of weeks to put this one together, but I have been doing a short session at a time, say 1 to 2 hours. There are no really hard bits to the construction, there is just a lot of it! The board solders extremely nicely, you can tell that it is a good quality board. I am very impressed by the overall quality of the kit, there is no wonder that Elecraft kits fetch good money second hand.

I'd definitely recommend the K1 kit and I haven't even tried it out on air yet! I would say that it's the best kit building experience I ever had, it's so nice when the instructions are so confidence inspiring and everything is explained in detail.

I have yet to add the KAT1 ATU board to the K1 - the board is fully populated, but I want to give the K1 a thorough try out first without the ATU to make sure everything is working as it should. I hope to try out the K1 this weekend. Once I'm happy everything is OK with the K1, I'll plumb in the ATU. I have never had the luxury of using an auto ATU, so it will be a new experience for me.

The K1 goes back to it's owner at the end of October - I'll be sad to see it go, but I'm very proud of my work. Hopefully I'll get to build somebody else' Elecraft kit in the not too distant future! Any offers? :-)

Hi Mite 17

Well, hasn't time flown by! I can't believe that we are already well in to October.

Back in August I started to build a HiMite 17, using my usual Manhattan style construction technique.

I got the circuit almost working but have since put the project on hold. I hope to get the project finished in the not too distant future.

I used crystals supplied by Graham G3MFJ at G-QRP club sales. Graham has just started stocking 18.086 MHz crystals, this now being the preferred frequency for QRP CW on 17m. I followed the schematic for the HiMite 17 devised by Dave Benson, K1SWL. Dave uses inductors in series with the VXO crystal to pull it down a bit as the crystals originally used were cut for 18.096MHz. I also used an inductor so my rig operates at slightly lower than 18.086MHz.

The frequency of the rig can be 'wiggled' by the use of 2 potentiometers to change the RX and TX frequency a little bit.

I seem to have lost my supply of violet LEDs, so I used a pink one instead - isn't it pretty? :-)

This rig is still a work in progress, I do hope to get it on the air soon!

New RockMite 20

Tom, M1EYP, and I had a discussion about LA1KHA's PP3 challenge a while back. Tom is convinced that 20m is the best band to find SOTA chasers whilst running flea power from a PP3 battery. I had to try out Tom's theory!

I ordered two RockMite 20 kits from Dave, K1SWL at Small Wonder Labs. The kits arrived in about 2 weeks from ordering - Dave had been waiting for parts shortages. I ordered two kits as I wanted to use the parts of the second kit for another project - watch this space!

My original RockMite 20

I already have a RockMite 20 in an Altoids tin. I worked N1WPU, Ted in Stockton Springs, Maine, back in September 2011 with my original RockMite, I cherish my RockMite for that QSO, I had joked to my friend minutes before the QSO that my aim was to have a contact with a US station using my 330mW - I couldn't believe it when it actually happened! Apparently my friend is still telling the tale! I really couldn't bring myself to modify the rig for Kjell, LA1KHA's, challenge, so I decided to order a new kit to modify.

The new kit went together without any problems, but I did substitute the zener diode feeding the varicap with a 5V1, I found the original 4V7 zener did not provide enough TX/RX shift. Dave is now shipping MVAM109 varicaps with his RockMite kits, supplies of our beloved MV1662 have mostly dried up. The MVAM109 is a pretty good substitute for the original varicap, but I find it needs more voltage to provide the same capacitance.

I again decided to build the new RockMite in my usual style, using a box from Maplin. I added a volume control, as  I find this improves both selectivity and  current consumption. I removed the PA collector choke and used a 4z-1z transformer instead, I also switched out the zener/resistor regulators, using a single low drop out 5v regulator instead to supply the mixer and PIC - see previous blog entry about low current mod.

So, how does the rig perform? Pretty well I'd say! I took the rig with me on my recent SOTA activation of Great Whernside, G/NP-008. I connected the rig up to my PP3 challenge battery, now measuring under 8 Volts, and sent an SMS spot to the SOTAwatch spotting service. This was the first time the rig had ever been connected to an antenna, would I get any replies to my flea power (~89mW) CQ's? Well I did get a reply, immediately after my first CQ call, I was answered by Barry, N1EU, in Delmar, Albany County, New York! Talk about an opening score - the QSO was across 3239 Miles, which equates to 36,393 Miles per Watt! I have applied and have been approved for my QRP ARCI 1000 Miles per Watt Award (KMPW), I think I just scraped though the award criteria ;-)

A new Son!

I have not updated my blog for a while, but I have a good excuse.

I'm pleased to share news of the birth of my second son, Samuel on July 4th, weighing 9lbs 8oz.

Samuel is doing really well and at 7 weeks he already weighs over 14lbs! We are all managing to get plenty of sleep, so all is good :-)

SW-20+ gets a paint job

I finally managed to get a coat of paint on my Small Wonder Labs SW-20+. I tried to make it look at least reminiscent of the case at one time supplied by Dave K1SWL for the SW series.

I'm quite pleased with how the radio turned out, I think it looks quite smart, although I put the labels in the wrong place because I was working from memory! Doh!

Dave K1SWL discontinued the SW series back in March 2012. The Small Wonder Labs website states that an easier to build replacement for the SW series will be available sometime in the future. http://www.smallwonderlabs.com/