KD1JV MTR

Back in April, I read a post by Peter, G4ISJ, on the SOTAwatch reflector about a new kit by Steven Weber, KD1JV. I had studied a few of Steven's designs before, especially the ATS series of rigs. I'm quite new to using CW on the air, and the cost of the ATS kits always put me off - I couldn't justify spending $200 plus on a rig that I didn't have the skills to use.

The post by Peter, G4ISJ, on the SOTAwatch site gave a brief overview of the new 'MTR' or 'Mountain Topper' rig and the fact that, as usual with Steven's kits, the sales had been brisk. I looked at the specifications and thought that it would be a fantastic kit and at $100, I thought it was very good value for money, if not a steal! I thought I had missed  my chance to order a kit as Steven had made only 150 kits available, each with it's own serial number, Elecraft style.

I joined the ATS (Appalachian Trail Sprint) Yahoo group immediately with a view to learning more about the rig and to make sure that I would be informed of any further availability of MTR kits.

I was very pleased to see a post on the Yahoo group a day later stating that around 50 MTR kits remained available. With my 33rd birthday just around the corner, I thought the MTR would make a superb present. With my XYL's permission (!) I placed an order. I had a couple of days of wondering before Steven confirmed via email that my order had been successful.

My kit, serial number 131, arrived just before my birthday, I wanted to start building it straight away, but construction had to wait until after we had been away on a family holiday.

The MTR kit is almost fully based on surface mount components. I don't mind soldering SMD's as I work for an electronics company doing repairs on circuit boards.

I found the quality of the kit and instructions excellent, although I would say that the MTR is not a kit for beginners. I built the kit using a fine tipped, temperature controlled iron, soldering each component by hand, one at a time. I took my time building the kit over a couple of weeks.

The most difficult part of the soldering was to mount the processor chip. Steven, KD1JV kindly sent a replacement chip via airmail, after it was discovered that the original version of the MTR firmware had a serious bug. The yellow dot on the new processor chip, added by Steven, shows that the corrected firmware has been programmed. I kept the yellow dot on the chip as I feel it's an important of the MTR's history.

Unfortunately the replacement processor chip had suffered a bit during it's Atlantic voyage and had bent pins, which took me a while to notice! I tried for ages to mount the processor chip, before I realised that some of the pins weren't actually touching the board! Viewed from above, all looked fine, but when viewed from the side, the problem was obvious. I put the processor chip flat on the desk, holding the body down with one finger whilst I pushed the pins down as firmly as I dared using the butt end of a pair of tweezers. This worked well, the pins now touched the pads on the board. The soldering of the processor then went smoothly.

Unfortunately the board suffered a little bit during my initial attempts to mount the processor, this can be seen if you look carefully at the photo - the solder resist on the right hand side of the processor has been scratched slightly, but these things happen!

The top side of the board went much more smoothly, it was really nice to be soldering the more interesting parts, the little LED display and the push button switches, these are the real interactive bits! The three slide switches are for band switching. All three switches need to be moved to change bands, either all to the left for 40m, or all to the right for 20m. If wanted either of the bands could be swapped for 30m or 80m, it's up to the builder to decide which two of the four bands available to choose. The 'Made in USA' bit makes me chuckle - mine was made in England! (OK, I guess it means the PCB was made in USA!)

Initial testing and alignment was performed in my garden! I was amazed by the performance of the receiver, it is very selective. There is almost no background noise on receive, you almost think that there is a fault with the antenna, but then you tune around and the wanted signals just jump out at you very clearly. The tuning takes some getting used to, it is rather slow if you only use the up and down buttons. The entire CW portion of the chosen bands, in my case 20m and 40m can be tuned. One neat function is 'DFE' or Direct Frequency Entry, this allows you to send the desired frequency to the rig in Morse code via the paddle key. This allows quick QSY to a known frequency. The rig reads back the VFO frequency via Morse code and by flashing up the figures on the display one by one, it works a lot better than the description would lead you to believe.

The MTR was designed to fit inside an Altoids tin and I felt it would not be right to fit it in to anything else but an Altoids tin. I managed to find a tin (and a spare, which would be needed due to drilling mistakes!) of Altoids at my local supermarket, although at £1.25 each, they are not exactly QRP priced these days! ;-)

It took quite a lot of work to get all the holes drilled in the right position, the PCB is quite a 'cosy' fit into the tin, but I managed OK in the end. The connectors can't be fitted low enough down the sides of the tin and still allow the lid to close, this is due to allowing for clearance of the PCB. Notches had to be filed out of the lid with a 'rat tail' file to allow the lid to close. The tin is actually used up side down, as the photos will make clear.

Steven, KD1JV, provides a handy quick reference graphic in the MTR build document, I printed out a copy and laminated it. It just fits inside the tin lid and it comes in handy to jog the memory whilst out in the sticks. It can be seen that this little rig has lots of available functions, there are 3 keyer memories, RIT, battery voltage meter, built in Iambic keyer and also the Direct Frequency Entry feature noted before. A quick press of the 'Menu' button gives a read back of the current operating frequency in Morse code, aswell as in figures via the LED display.

Most builders are using their own graphics for the top of their MTR tins, but I used the one provided by Steven, KD1JV. I like to think that I have done a good job with MTR serial number 131 and I hope that KD1JV himself would be pleased with my efforts.

The specifications of the KD1JV Designs MTR from the build instructions:

 

Dual band, 20 M and 40 M typical, 30 M and 80 M possible.

Receiver:

MDS: ~0.2 uV

Small signal band width ~ 500 Hz

Audio output limited to ~ 800 mv p-p

Headphone output, 16 ohms min recommended.

Minimum current (no signal) ~35 ma

Transmitter:

2.5 watts @ 9 volt supply typical

Spurs -50 dBc or better

I tried the MTR out from my local SOTA summit, Rombalds Moor (G/NP-028) a few weeks ago and I was very impressed with the performance. The receiver is excellent, very quiet indeed and very selective. The lack of volume control is not an issue whatsoever. I have yet to tweak the transmitter portion of the rig, but from 11v supply, my power meter was showing a healthy 4+ Watts on TX.

Overall, the MTR is an amazing rig!