OHR100A Build Part 2 (The Chassis and Alignment)

After re-checking all the soldering and making sure there were no obvious mistakes, I started on the chassis, firstly installing the SO239 socket and then attaching the optional ten turn VFO tuning pot followed by the AF and RF gain switches and the Bandwidth and RIT switches. The wiring instructions were fairly easy and I soon had everything connected up and ready for a smoke test. 

 All ready for the smoke test

The only problem was I didn't have a 13.8v power supply! The RockMites run off batteries and the FT1000 MP V has its own separate power supply. So on to Ebay and I quickly found an old but unused power supply for the princely sum of £15.

Two days later (a miracle in postal terms) the PSU arrived and after wiring in a 1A fuse I was able to carry out a smoke test. Do you ever have that feeling of dread, fingers on the switch wondering if you really will get smoke or just nothing happens? I must have been waiting for half a minute before I pulled up enough courage to switch the transceiver on. I turned the switch and bingo, the radio came to life ....what a relief!

Once I'd got hold of a power supply it came to life!

A quick play on receive and I found some cw, turning on the FT1000 MP and matching the incoming signal I could see that I was tuned in to 14.045 with the VFO fully turned anti clockwise, so I wasn't far off, the VFO toroid just needed some tweaking which was confirmed when I attached the MFJ 259 and using the frequency counter read that I was at 23.400MHz, just off the mark as the instructions quote 23.000MHz.

 So all I had to do was alter the gaps between the windings on the VFO toroid L114 to bring the frequency down to the required 23.000MHz as per the instructions. At the same time I had to tweek the caps for maximum power output between 100mv and 400mv, but this was fairly easy using my DMM. Once happy with the toroid readings it was a case of pinching some of my XYL's clear nail polish and giving the toroid a good coating and leaving for 24hrs!

 The toroid at L114  that needed a tweak

I must admit the hardest part I have found with this kit is the alignment, I've had little experience of this process but with the help of the instructions I managed to get through but it took time. You have to have a frequency counter and a DMM for this project and to be honest I'd never used the MFJ as a FC so it was all new to me and there are no instructions in the MFJ manual about how to set it up for frequency counting. In the end I attached a short piece of coax fitted a PL259 to one end and trimmed the earth off the other end leaving just the central wire. By chance I had a very narrow metal tube that fitted over the wire giving it strength and hey presto it was an excellent probe.

 The homebrew probe attached to the MFJ

The radio is now virtually complete except for the optional LED that I have to fit. I've had a good play but I haven't attempted a QSO yet, hopefully this will be done over the weekend. It's putting out a healthy 7 watts on the dummy load, but I've reduced this to 5 for QRP. First impressions are that the receiver is excellent especially when using the bandwidth, it certainly matches up to other radios I have owned. The 10 turn pot although smooth gives you little idea where you are within the CW sector of 20 meters so I suspect I will purchase the OHR Digital Frequency counter to make life a little easier.

Overall I'm really pleased; I've come along way since the early days of the RM builds and my confidence as a QRP builder has grown dramatically. Reading the reviews on Eham, the kit is probably classed as an intermediate, so hopefully I've passed with flying colours and now can look towards building my ultimate homebrew kit, the K2 !! 

In the meantime I shall enjoy working some QSO's with my trusty new OHR100A. Once I've added the LED I will post some pictures of the completed Radio.

OHR100A Build

Finally the OHR100A arrived but in the end I had to nip down to our local postal sorting office to collect it as they were complaining about how busy they were and it was going to take time to deliver. 

The parcel was well packed with individual sections of the kit separately kept apart which made things easy for identification. Marshal certainly makes sure of doing a good job in packaging as everything is nice and secure.

So the build of the OHR100A begins. To start with I thoroughly checked the inventory to make sure I had everything; I ticked off each part as I went and seemed to be all there so I could get on and make a start. I don’t plan to rush it; I’m going to take my time and build in roughly 2 hour slots so that I don’t over do it and make silly mistakes. The first part is to install several diodes and the IC sockets making sure that all are correctly positioned on to the PCB board before soldering.

The instructions seem very clear, certainly as good as the Wonderlabs notes which helps greatly when a newbie like me is attempting something a little more difficult than the RockMites. Amongst the instructions is an overlay sheet with clear diagram of where each part should sit which is very useful.

6 hours later and I’ve installed the diodes, chips, chokes, resistors, trim caps and capacitors, the only problems so far have been a slight issue with soldering as I’m having to re-apply a small amount on a few components to the top of the PCB board as the soldering is occasionally not penetrating through the holes, this is more likely because of the solder I’m using but in actual fact probably helps in double checking that everything is soldered correctly.

Approximately 9 hours later and I've all but completed the PCB board. Just the IC's to slot in to place and add in the Molex connectors. The toroids were a little fiddly but I think that is probably due to lack of practice and experience, but once I had done the first the others seemed to wind OK. 

Interestingly in the picture below you can see my one mistake that I had to rectify, which was placing the transistor D105 in to U104. As soon as I done it I realised my mistake but then had the job of carefully removing the transistor and then soldering it in its correct position. The one thing I've learned is that as soon as you feel at all tired take a break because that's when mistakes are made!

Now I have to assemble the chassis with all its components which hopefully won't take too long and then just wire up and do the smoke test.......More to follow!

Good News With the OHR100A

Well as soon as I started to worry that the OHR100A was lost forever in the vacuum of the postal ether I get a note from the Royal Mail telling me they have a package for me, but the bad news is I have to pay the sum of £35.50 for Customs and RM handling charges! £8 for handling charges, crazy! Anyway at least it's arrived and I know that soon I will  be once more happily getting stuck in to another building project.

The TH215-E has definitely shorted I found that the fuses J1,2,3 and 4 have all blown so something has caused it to fail. To be quite honest unless its a simple fix like an audio amp replacement I may just give up and buy myself another 2 meter rig off Ebay, we'll see.

Lost OHR 100A and TH-215E Problems

Still no sign of the OHR100A! I contacted Marshall at Oak Hills Research and he advised me to wait another week, before approaching USPS, but I have to admit I’m beginning to worry, I have ordered a few items from the US and they haven’t taken this long.

My only hope is that the package is stuck in the UK customs and it will hopefully arrive in the next couple of days. Looking on the USPS website Marshall kindly gave me a tracking number but all I see it that it was last seen in Jamaica NY on the 04/11, after that there’s no further information. It’s typical you build yourself up ready for your next project and then it doesn’t arrive!

Whilst waiting for the OHR100A I’ve been trying to figure out what is wrong with my old 2M TH-215E handheld. It switches on fine and even transmits ok but there is no sound coming from the speaker.

Using the MMD I’m getting output from the speaker and if I hold it close to my ear I can just make out the squelch, so I think it’s more likely it is the pot playing up. I’ve dismantled the radio and have attempted to give the pot a really good clean with some switch cleaning lubricant.

 The disassembled radio, on initial inspection all looks ok.

I’ve checked the PCB and can find no cracks or any sort of damage so at the moment I’m slightly at a loss as to where to progress from there. 

I've given the pots a really good clean but they are sealed units which does not help, so it's a case of gently feeding in the lubricant and turning the pot back and forth.

The speaker looks ok and I've checked the connections with the MMD and am getting output.

I suppose the options are that I make sure the extension speaker plug is not cancelling out the internal speaker, check all the traces to the speaker and last case scenario try and find another pot and replace the old one. ................Anyone had a similar problem let me know!

Audio Amplifier Kit

Still waiting for the Oak Hills Research 20 meter kit to arrive although strangely the LED kit turned up the other day, but nothing else. 

So I’ve been tidying up the shack and getting all my soldering irons cleaned up in readiness for the big day. I also purchased an audio amp kit this time with a bit more power 7 watts, my home brew audio amp is fine but lacks oomph. The new amp works well with the RMs and just means I can listen out to who is around when out of the shack in my other workshop.

I've also had ago at installing the CW filter I bought from Hamshops, and although it works  I don't think I've set it up correctly. when I add a 9v battery there is no change in sound so the small amp doesn't seem to be working. Without the battery the filter continues to work but all received signals are just quieter and there doesn't seem to be any filtering. I suspect when I originally built the filter I messed up the soldering of the amplifier hence its not working, however I will carry out further tests and see if I can find out the problem.

All three RockMites are now safely in the shack and used most days when I have the chance to play radio. I've had some good contacts especially with the 20 meter RM where I've gone over 1k miles which I'm pretty pleased about. The 30 and 40 get good contacts with Europe and the average distance is around 500 miles which is nothing to be sniffed at.

In fact the shack is looking pretty good a the moment and I'm amazed how it slowly filled up with various bits of kit. So I had a bit of a spring clean and re-organised things especially as I know I'm going to have to find room for the extra OHR 100A. In my haste to clean up I dropped my old Trio 2 meter handheld, it still switches on but there is no sound I've checked the speaker connections and they are all working so I suspect it's something a little more serious, never mind it will keep me occupied during those winter months, or it's an excuse to go out and buy myself a new one!

Do you like my old Royal Enfield in the top right corner?

Another QRP Kit

Well I’ve gone an ordered another kit, this time it’s the Oak Hills Research OHR100A

I suppose once I’d seen it I knew it was the next sensible step up from the RockMites, I’ve chosen the 20 meter version, I did think about the 30 meter but quite honestly the last RM I built was for 30 meters and its working so well that I really don't need another rig for that particular band at the moment.

This rig has a bit more power 5 watts, so I should get a lot more first time contacts, thats the one thing about RMs, you have to be patient when calling CQ!

I'm really looking forward to it's arrival I think I'm definitely addicted to QRP building and this should be fun. Not sure how long it takes to dispatch but also I will need to take into consideration all the problems that hurricane Sandy may bring so I need to be patient.

I’ve also ordered the extra 10 turn VFO tuning pot and the LED kit, I thought I might as well get everything straight away.

This build will really be the prototype for the main event the K2, so I hope I find it fairly straight forward in construction and also put in to practise all that I have learned when building the RockMites.

Providing all goes well I will add photos and descriptions as I go along, might prove interesting for some budding home builders. If it’s all successful then I will certainly start looking at the K2 but I doubt I will get that until sometime next year.

The Higher Bands Open Up

I have just been skimming across the bands and this morning 28MHz is wide open, I’ve heard VKs VUs and ZLs and it’s a refreshing change to the normal quiet hiss of the band!

Interestingly there never seem to be any slow operators in the early morning, whenever I switch on first thing you always hear the diehard Dxers tapping away, mostly at speeds that I find difficult to keep up with.

Always first thing in the morning when I fire up I'm too keen and I have the typical CW operator’s problem I find I can send faster than I can receive. I call it BNC (Brain Not Correlated).

Sometimes when I hear a distant station and dive in giving a quick reply they come back at me like a machine gun because I’ve gone in at such a quick speed.  I then have to put my brain in to gear and concentrate very hard to translate the reply.

If it’s a standard reply such as “gm es tnx fer ur call ur rst 599 etc”, then I’m ok but if the conversation alters then I really need to buckle down and think! Its classic mistake that operators can make, but it’s not the end of the world, after all it’s your hobby so enjoy the challenge and it's a great way to speed up your code!

I’m still at a loss at what kit to build next, I’ve been looking at my ultimate build, the Elecraft K2, I just love that transceiver and a real challenge to build, but like all things it comes at a price which is something I just cannot afford at the moment, but one day I am going to buy it, it’s just a matter of time.

I’d also love to have the K3 the ultimate CW operators rig, but its a lot more money (nearly £2k) and I already have my super rig, the FT1000 MkV which is a very good radio. So if I ever did buy the K3 the MkV would certainly have to go to part finance the K3, which I'm not sure I could do.

In the meantime while I dream for my super kits I now want something to fill the gap of the RMs, basically it must be a challenge above the build of RockMites so more than likely its going to be a Hendricks or Oak Hills Research kit.

It must be a minimum of 5 watts with CW only and definitely have a VFO as I’m not too keen on being limited to a small section of the chosen bands.

Certainly with the RockMites it can be a pain when you switch on and the band is swamped within your particular frequency, you have little or no ability to move away. I know you can mod the RockMites but I feel I want to keep them as they are and move on to something new.

In the meantime I’ll carry on tapping away at the key especially whilst the higher bands are open.

A Simple Manual Antenna/Radio Switch

Now that I have three RockMites and one FT 1000MPV to play with I wanted to make it easier to switch from each radio, the simple solution was a basic antenna/radio switch.  

I had an old 3 way Altai switch from years ago but quite honestly it was a cheap bit of kit and anything above 50 watts it would probably burn out. So I decided to build my own using various bits of junk I had in the shack.  

I pinched the four SO239s from the Altai which were fine but interestingly on further inspection the Altai was definitely on its last legs, the plastic switches on it were virtually worn away. After rummaging further in the shack I managed to find another SO239 to make 5 connectors in all.

I also had a small aluminium/aluminum enclosure which would do nicely for the case and being metal would take care of the groundings and any stray RFI. I found a one pot 4 way rotary switch, but it was plastic job, fine for a guitar or something similar but I doubt would have lasted very long for what I wanted.

So I decided to buy something heavy duty and after trawling around the web I found a UK company that sold 1960s rotary switches and I spotted a good solid 1 pot 4 way switch that would be just the job.

It cost me £6 but when it arrived I knew I’d bought the right switch, it was a good solid bit of kit, nice and heavy with a break before make connection.

I soldered some 14 gauge wire to the SO239s and fitted them to the enclosure, after cleaning up the switch I drilled another 16mm hole in the top of the enclosure and fitted it in to place. 

Finally I connected up all the 14 gauge wire from the SO239s to the switch and gave it a smoke test. The SWR was good on all five connections and another useful bit of kit was completed. 

The nicely thing now is that I'm not chopping and changing antenna connections to different radios all the time, with a simple twist and satisfying "clunk" of the heavy duty switch I can connect to each radio with ease.

Oner Stockton Wattmeter

To get an idea of QRP power and SWR for the RockMites I bought the "Oner" Stockton Wattmeter from Kanga Products. 

It comes in kit form and is a simple circuit and fairly easy to put together. I suspect many QRPers will know of it and what a useful bit of kit it can be. It only took me half a day to put together and now at least I have a more accurate means of measurement. 

I had an old enclosure that was able to use to fit the kit, the hole for the meter was a bit too large, but a bit of tape fixed the problem otherwise all the other connectors and parts fitted in nicely!

  

I'm at a bit of a loss now, no more RockMites to build and although I'm having fun operating them I need some kits to build, I've obviously become an addict! I think I've said before I've got my eye on the 5 watt CW kit from Oak Hills Research or possibly the similar CW kit from Hendricks.

We'll just have to wait and see and to be more precise what I can afford!

RockMite 30 Update

Well some good news, I’ve had my first QSO with the RM30 but there have been some minor issues along the way.  

After completing the build and doing some further testing  it became obvious that the transmit was not working as it should, I was using the 2N3053 transistor with the 2 ohm resistor in R18 and of course the bifilar toroid filter mod in L1, but I was only getting about 400Mw out when I should have been getting around 700Mw.

On further investigation/checking and through chatting on the Yahoo Rock-mite forum it eventually came apparent that I was using the wrong toroid FT37-6 as opposed to T37-43.

 Unfortunately I did not have that particular toroid so after having a good think realised the best way forward was to revert back to legacy and remove the T37-6 and pop L1 back in and use some jumps to bypass the trace cuttings.

Actually surprisingly enough it did not prove too difficult and I soon had the RM back up and running pushing out approximately 600Mw of juice.

At the same time I had a play with various transistors I have, the standard 2N2222 and the 2N3053 plus another, the 2SC799 which in theory can give you up to 2 watts of power. Sadly with my RM30 it hardly gave me any power, so either it’s broken or my set up is incorrect for that transistor.

So I reverted back to the 2N2222 and after a couple of attempts Calling CQ this morning I got DL6FAX, Konrad in Korbach a distance of 670 miles , not bad for my first attempt and Konrad was kind enough to give me a 569!

I’ve now ordered the correct toroid which should arrive later this week and then I will do some further experiments and we’ll see how we go from there.

The main thing is all my RM’s are now built and thankfully working correctly, something I would not have dreamed of if you had told me at the beginning of the year. 

Some further news regarding batteries, at present I have been using standard 9v batteries, which are fine but obviously not rechargeable. A member of the Yahoo RockMite forum announced last week that he had purchased a re-chargeable 12v battery from China which by all accounts seemed to fit the bill for RockMites really well.

So I took the risk and also bought one, it arrived the other day and I’m really pleased with it. It comes complete with charger and 3 pin plug (for UK users) and seems to hold the charge pretty well. It’s excellent for when I want to get out and about, not bad for £8.00!