SW40+ QRP transceiver – Ready for action!

Finally, the SW40+ project is over. I did not updated the status for a long time, although a lot of things happened!

After completing the assembly of the kit (toroids and final transistor) I was ready to make all the adjustments. In the mean time, the enclosure had arrived and I chose to install it first and then adjust it. The enclosure kit comes with a BNC antenna connector and at the time, all my other equipment uses PL-259  so  I bought some adapters to use until I make a final cable with a BNC plug.

After connecting my main antenna to the SW40 through the adapter I started adjusting the receiver. It sounded a bit deaf, meaning, that there was not quite big difference whether the antenna was connected or not. This puzzled me a lot but I decided to continue with the transmitter part.(This proved later to be a big mistake!).

I connected the transceiver through my power meter to a mini dummy load and  started keying the transmitter. There was no output at all! No matter what I did, the transmitter was dead.

It took me about 3 hours of thinking and signal tracing to make the discovery. The BNC to PL-259 adapter was faulty…actually, it was shorted! All the transmitter testing was performed with a shorted output! This resulted in a fried output transistor, and I had to order new ones from Small Wonder Labs!

After replacing the output transistor (and disposed the faulty adapter!) all the adjustments were finished within minutes. The transmitter is capable of delivering something more than 2.5 watts  (as displayed on my power meter, with unknown accuracy !) but I set it to about 1.5 Watts for safety.

The SW40+ finished

I have used it a bit, mainly on receiving (yes, my CW skills are still bad…but they are improving fast!) and it is quite a pleasure! The receiver is sensitive enough and can hear almost everything my main rig hears (which means that they are both either very good or very bad!).

There are two thing that someone has to get used to. First, is the tuning pot. The tuning range of the VFO is small but for a single turn pot, it stil feels that it tunes too fast! Also, it is a bit non-linear, because, there is a small range at the beginning and a bit smaller at the end that does not actually changes the VFO frequency. It is not very serious though and there are a lot of mods to fix that as well as the tuning range.

The other thing is the lack of AGC , which for someone that has never used an AGC OFF switch on his transceiver, is a bit strange! On the SW40+, most of the time when tuning and the GAIN is on the max setting, very strong signals appear from nowhere  at  very “annoying” levels !!! It takes a little practice to learn to tune with both the TUNE and the GAIN control.

Another view of the SW40+

However, none of the above  issues can degrade the quality of the transceiver and are not at all annoying. It is  just something that take about 2 hours to get used to! The on-the-air performance is very good and it makes a very compact and portable transceiver that I am going to enjoy for a long time!

I hope to meet you on the band, soon!

73, SV3DJG

SW40+ QRP transceiver

I like portable operation and I have a transceiver allocated exclusively for this purpose. It is a Yaesu FT-890AT which is fine if the operation is something serious ,like a filed day, but it is a bit of overkill for taking along on a weekend or on a business trip just for  fun.

For more relaxed operating I need a transceiver quite small in size, with low output power (QRP) and low power  requirements. I had seriously hard time deciding on the band, I wanted them all! After a lot of though I decided to try 40m and the transceiver should be a kit.

So,  I ordered a SmallWonder Labs SW40+ , one of the most popular single band transceivers available. Believe it or not, after my order was received, I had the kit in my hands in 5 days!!! (After I got it, I was really sorry that I did not also ordered the enclosure, which I did a bit later).

The kit quality is outstanding! There is no missing parts, everything is clearly marked and even a beginner can assemble this kit. The pcb is single layer but with plated-through holes and as I discovered later this adds to the mechanical stability of the kit. When you solder a component, the solder is flowing  through the hole and reaches the other side. When you turn over the PCB on the components’ side it seems like the component is soldered on both sides! Excellent!

I followed the instructions and I was surprised to see that it was easier than I thought, after 2 hours this was my progress

Progress after 2 hours!

I was amazed at my progress because I was proceeding slowly  ( I prefer to be more careful than required and  double check  everything than coming back because something was misplaced).

I decided to  go on a bit more and after 2 more hours the kit was almost complete,I had soldered everything but the toroids and the final transistor.

Progress after 4 hours!

Then I had a small shock! I had one resistor lying on the table!!! How did this happen? Did I miss something or did the kit contain one more resistor? I inspected the kit thoroughly but without luck! It must be a spare resistor (at least this is more convenient to me)!

I would have finished it today, but I want to check it tomorrow with a clear mind, just in case I missed something. Besides that, winding toroids is not one of my favorites and it takes (me) a lot of time. So, the project will continue tomorrow!

73, SV3DJG