KIT BUILDING!

There's little that I like more than having an electronics kit sat waiting for me to make a start on it. Typically, I buy one and then leave it on a shelf for a good while, waiting for the perfect time to begin construction, with an equal mix of apprehension and excitement.

I know practically nothing about electronics and yet I've been building little 'hobby' projects for years, starting with Veroboard kits in the 80's and 90's from Practical Electronics magazines and similar publications (do you remember the Penfold series of books?). I have many fond memories of dashing down to my local electronics store (Modern Radio in Bolton) to give them my list of components as prescribed by the project author.

I never really understood what I was doing, but I thoroughly enjoyed putting the 'puzzles' together. Sometimes I got it right and sometimes I ended up walking to the trashcan. Even when things didn't work out for me, I was never really disappointed enough to quit - in fact it made me more determined to get the next project right. Many of the kits I made back then had pretty obscure uses, but some were related to my main hobby of SWL. Happy days 😊

In more recent times, I've turned to proper kits as opposed to magazine projects. Things which are made professionally and are related to Ham Radio usually. The first kit was a simple transistor radio based on a famous design from the 60's. This was a gift from my wife and I really enjoyed putting it together. It sits on a shelf nearby and is regularly used. It's a Tecsun 2P3 and is available from Amazon amongst other places, for less than £30. It takes no time at all to knock together and is just light fun.

After that, I discovered QRP-LABS and decided to try building their QDX Digital Transceiver. It was in high demand and it took me a while to get hold of one. I loved this kit so much that I ended up building another one. They perform magnificently and the quality of the kits is extremely high (and so too is the documentation and support from Hans Summers). It's an easy to build kit and should present few problems. For me, the toroid-winding was a little difficult because I'd never wound them before and I dreaded it! But now I realise just how straight-forward they actually are.

The QDX builds taught me quite a lot and formed a good foundation for my future builds. Next up was a QCX which I stumbled upon at a Radio Rally. From memory, it cost me a tenner and although there was a big problem during the construction of this kit, it taught me some valuable lessons in patience and perseverance.

 

Around the same time I discovered KANGA kits and ordered their 2W Rooster CQ Transceiver kit. This was a cheap, very simple build and was good fun. I've since ordered the new RockRose Kit.

In addition to the above transceiver kits, I've also built a couple of the Kanga antenna transmatch units, which work really well and are easy to build.

My next QRP-LABS kit was the wonderful QMX, but boy, it was a tough build!! Having said that, it worked straight away and I was quite pleased with myself considering the fact that the twin (stacked) PCBs in this radio are tightly packed with components, leaving almost no space between them. Unless you are desperate to build a tiny transceiver, I would advise you to skip this kit in favour of the PLUS kit below.

And so my next Hans Summer kit was the QMX PLUS which is infinitely easier to build than the regular QMX. The reason for the ease of build is the much larger design which uses a single PCB. Having said that, some of the solder pads on this board are incredibly small, making it difficult to get your soldering iron to make equal contact with the pad and the component. The large ground plane adds to the difficulty. Other than that though, it's a pleasure to build this kit (although my kit had a faulty PCB) 😮.

Another enjoyable kit was the EXPLORER from Radio Kits here in the UK. This one had over 800 soldering points but it didn't feel like there were that many. I really enjoyed this one, even though I experienced some issues. I'm pleased to say that the designer was incredibly helpful with troubleshooting ideas and pretty soon the radio was up and running.

Next up was a compact ATU from AliExpress. Cheap, cheerful and effective! Capable of handling 100W (they say), so definitely capable of handling 25W of constant carrier operations such as FT8, leaving a wide safety margin. You can find these all over the place and they're very easy to build.

I've also put together a HERMES LITE II PLUS kit which isn't much of a kit at all - more of a modular design which involves very little work at all. Having said that, I did a couple of mods on mine. These are superb SDRs by the way!!

Finally, I recently put together a portable FT8 kit requiring no computer to operate - it's a self-contained transceiver with a colour touch-screen and a tiny output of 0.5W. It is easy to construct and works amazingly well!

So that's about it. I've really enjoyed tinkering with these kits and look forward to building more as and when they become available. The QMX PLUS has been particularly rewarding because it has turned out to be an incredibly capable transceiver and the latest firmware has added SSB to the mix. If you only ever build one kit - make it this one!

And if you're not feeling very confident, please - just have a go!! What's the worst that can happen?

Thanks for visiting the blog.

73, Tom, M7MCQ.

TECSUN PL990X 2024

This is a quick look at the Tecsun PL990X Triple Conversion, Multiband SW portable radio. It's the sort of radio that I tend to use with a copy of WRTH to hand and a couple of hours leisure time. I've always found shortwave listening fascinating and if you're reading this post, then you no doubt understand why.

I already tried a Tecsun PL680 and an S2000 and was happy with both of them, except for the size - one was too big and one was too small. The S2000 is a bit of a whopper and reminds me of the old ghetto-blasters that you used to see in the 80's and 90's. They have a real presence and all that real estate means that you can get some great speaker units inside the case, so for taking out in the garden at home or sat at a picnic table, you can enjoy some quality listening time. But they're pretty useless for lugging around with you away from home.

The PL680 is much smaller and it's a good radio, but the fact is, I fancied something with a bigger speaker - nothing huge, but something which had clearly better audio and give me a more comfortable listening experience - especially on FM and SSB.

The new 501X from Tecsun is bigger than the 680, but it's a step too far in terms of size and price, so that was out of the question. Somewhere in-between is the PL990X and that's the one I decided to buy.

The 990X is the replacement for the well established (and well liked) PL880. I was actually considering a used 880 but I always feel drawn towards the latest designs which usually have more features and have the bugs of the previous model ironed out.

Needless to say, I did not want to pay the full retail price of the radio, so I had to be patient and use my usual techniques to find a bargain. In the meantime, I advertised my PL680 and got the most I could for it using a great advert. In the end, it cost me £85 to swap.

When the PL990X arrived in the post, the opening of the package was a very pleasing experience - the presentation of the product is first class as usual. The radio comes in an attractive box and contains a nice faux leather case (as did the PL680) and a useful retractable wire antenna. There was also the world call-sign map and fold-out guide. It's a really nice little package and you get the feeling that Tecsun haven't skimped on anything.

 

The radio is powered by a (supplied) single 18650 3.7V Lithium Ion rechargeable battery which is unbranded, but lasts a decent amount of time and the battery-indicator seems to be usefully accurate. I already own some high quality, high capacity 18650 batteries, so I'll switch to them to improve battery-life further still.

 

 

Handling the PL990X for the first time gave me the impression that it's quite a beefy radio, but it's only because I'm so used to handling the smaller 680. After a while, I was happy that it was 'just right' (sounds like the Three Bears story) and this would definitely be my go to radio for general SW listening.

The quality of build is typically 'Tecsun'. I really do favour this brand and have never been disappointed with their products. The plastics and general fit and finish has always been of a good standard and the controls always seem to feel smooth and yet rugged - sometimes more so than on some other more expensive radios from the big name manufacturers!

 

The antenna feels smooth and well made, but I really do wish that manufacturers would consider fitting a BNC connector to their larger radios - that way we could quickly and easily try out different length telescopics. Speaking of antennas, they include a wire antenna on a retractable spool and whenever you're using an external antenna, you get the (important) option of being able to bypass the internal antennas (ferrite and telescopic) by flicking a switch on the front fascia. Another switch below that, adjusts the front-end gain.

One of the best things about the PL880 when it was introduced back in 2013 was the radio's audio quality and I'm pleased to say that its successor has carried that forward. The sound from the single speaker is really pretty good at normal volume levels. 

Broadcast stations on FM sound fabulous and connecting a decent pair of stereo headphones makes it an even better experience. SSB signals sound great too. Like other compact radios, things can head South if you crank up the volume too far, but in the main, it's very pleasing. Some claim that the 880 has a slightly better sounding speaker and that might well be true, but the fact is, it's discontinued model and the newer features and improvements of the 990 more than compensate.

Unlike the PL680 the 990 has no AirBand coverage, which is a great pity. To be fair, I tend to use dedicated AirBand radios with fast scanning abilities but it's always nice to have the option of tuning to a single frequency such as your local Tower and listen in while doing something else.

The 990 benefits from having switchable LSB/USB and I have to say that the audio is far better than on the PL680. I was particularly impressed by this and was reassured that I'd made the right decision upgrading. Another big difference between my 680 and the 990 is how the 680 is very sensitive to touch - having your hand too close to it altered the signal strength, which was annoying. Thankfully, the 990 is fine when being handled.

Synchronous Detection is available and I found that it works fairly well but does introduce some unwanted filtering of the audio on certain frequencies. From what I've read though, this is infinitely better than the 880 (so the 880 must be real bad).

When listening to the ham bands on SSB (something I do a lot), the AGC seems a little slow to react, but I have to remember that I'm subconsciously comparing it to my (costly) ham radios, which is kinda unfair. I guess I'm being a little picky about it.

Tuning around on the 990 is a very pleasant experience. I love the knurled tuning dial and the equally useful fine-tuning dial. On the top of the dials there's a friction pad to make it easier to turn them with your fingertip. Direct-Input of frequencies is simple, making well known stations easy to tune into.  Needless to say, the radio has a massive memory bank with useful 'Pages' for grouping. With the rear stand flipped out, this radio is supremely comfortable to use as a desktop radio.

Using the built-in telescopic antenna, the sensitivity of the radio is really quite good and I did a few side-by-side comparisons with other radios including my Belka DX (a miniature marvel which positively shines on its (BNC) telescopic) and my IC-705. They compared favourably and the same could be said when connecting an outdoor antenna. 

With the 990 connected to an outdoor EFHW, stations from much further afield could be pulled in, but it's important (IMHO) to use a coupler or manual atu in order to get the best out of the antenna. You don't have to buy something expensive - you can use something cheap from a radio-rally or buy a Kanga kit or maybe use a ZM2 if you have one. But use something!

Other features of the PL990X include an SDCARD slot which can be used to store MP3s for replay through the radio's speaker. There's even a useful bank of control buttons for Play, Pause, Stop, etc. Sadly, you cannot use the card for recording signals from the radio (probably due to some copyright laws). Initially, I didn’t think I’d use the MP3 player much, but I actually use it quite often and I love how you can use the Main Dial to move through tracks and the sub dial to move through albums.

Another useful feature is the built-in Bluetooth. This allows you to connect the radio wirelessly to something like your iPhone which is great if you want to play music, podcasts, etc.

On the left side of the radio there are sockets for external antenna, line-out, headphones and a USB port for charging (charger is included). The USB port can also be connected to a PC to play computer audio, but I can't imagine many people will. On the other side is a slider to alter the audio tone. On top of the radio is the option to put the radio in snooze-mode, adjust the display or lock the radio.

CONCLUSION. This brief look at the PL990X, leaves me thinking that it's a real nice bit of kit which works extremely well, is fully featured and has a lovely sound in all modes of operation. Even CW sounds nice and crisp with the 500Hz filter engaged.

Guzheng/Guqin

There’s something quite magical about sitting on the sofa, radio in hand, tuning through the bands and virtually travelling across the globe, listening to different music, languages and viewpoints. I can never quite explain to people why I’m able to enjoy listening to some pretty esoteric music, such as a Guzheng player in a studio 6,000 miles away! I think it’s something to do with my experiences as a youngster with my little 6-Transistor radio. 

It's a nicely sized package (as the actress said to the bishop) and is super easy to use on a desktop or in your hands. I’m absolutely over the moon with this radio ands would strongly recommend it. The biggest drawback is the (UK) price of £269 at the time of writing. I think it cost far less at the time of launch, but prices of electronic goods have rocketed over the last couple of years. If you're willing to chance purchasing directly from a China based store, then you can drop that price significantly. Or alternatively, buy second-hand.

Features of Tecsun PL-990x radio:

• FM reception range 64-108MHz, suitable for global FM broadcast reception.
• Single sideband (SSB) 10Hz minimum step, independent selection of upper sideband (USB) and lower sideband (LSB).
• Synchronous detection range +/- 1kHz
• Arrangement for connection of an external antenna for SW reception
• External antenna input for all bands
• Local, Middle and DX input selector
• Independent fast and slow dual tuning structure
• Seven methods of channel selection: automatic search and store (ATS), manual search of pre-stored stations (VM), manual search of station frequency (VF), direct entry of frequency numbers, direct entry of station address numbers pre-stored stations, automatic navigation of radio frequencies and automatic frequency display of pre-stored stations
• Storing up to 3150 radio frequencies in 25 memory pages
• Ability to play SD card, supporting 16bit/44.1KHz WAV, FLAC, APE, WMA and MP3 format audio files
• Class AB power amplifier and super dynamic full-range speaker
• Headphone output, suitable for stereo headphones below 300 ohms
• Audio output, for external amplifier or recorder
• With programmed switch-on and automatic switch-off function
• Powered by 18650 lithium battery, with USB smart charging function

Specifications of Tecsun PL-990x radio:

• Longwave (LW) 100-519kHz; 9 kHz steps, 1 kHz fine tuning steps
• Medium Wave (MW): 520-1710kHz; 10 kHz increments, 1 kHz fine-tuning increments; 522-1620kHz; 9 kHz step; Fine tuning steps of 1 kHz
• Shortwave (SW):  1711-29999 kHz with 5 kHz step, 1 kHz fine tuning step
• FM: 64-108Mhz, 76-108MHz, 87-108MHz, 87.5-108Mhz selectable, FM tuning step 100kHz/10kHz
• IF Frequency: AM   1st IF, 55.845 MHz, 2nd IF, 10.7 MHz, 3rd IF, (DSP) 45 kHz
• Audio Format: supports 16-bit/44.1kHz WAV, FLAC, APE, WMA and MP3 formats Micro SD (TF) card up to 128G (not included)
• Speaker: 4Ω, 3W
• Diet:  3.7V (18650 rechargeable lithium battery)
• External DC Power: USB current 5V ≥1A
• Dimensions:  198x120x38mm
• Weight: 620 g

Tecsun PL-990x radio package includes:

• 1 TECSUN PL-990x receiver
• 1 x 18650 lithium battery
• 1x external antenna
• 1 Hi-Fi Stereo Headphone
• 1 x USB charging cable
• 1 USB charger

(Frequency limits vary according to tuning step settings)

LW: 50-519/50 - 522 KHz (LW can be disabled if desired)

MW / AM: 522-1620 / 520 - 1710KHz

SW: 1621-29.999 / 1711-29.999KHz

FM: 64-108 MHz (lower limit selectable at 64, 76, 87 or 87.5 MHz)

Tuning Steps: LW/MW 9Kkz/10Khz/1Khz

FM: 100KHz / 10KHz (PL-990X only: 50KHz when AM set in 9KHz steps)

Direct frequency entry from keyboard

Page memory system with VF (Frequency Display) / VM (Memory Display) switch

Scan Up / Down / Auto or Manual Auto Tune Storage

Main and fine tuning knobs

FM Stereo / Mono switch

Triple conversion on LW / MW / SW

SSB with LSB / USB mode

Synchronous detection with LSB / USB mode

SW Meter Band buttons

Memories: 3150 total positions with 25 memory pages

DX / Norm / Local gain switch for all bands

Clock (24 hour mode) with alarm clock, sleep timer, snooze

Multifunction display with time / signal / SN ratio

The LED lighting can be set to Auto or Always On

Audio Player - Micro SD card 128GB max (playback only)

Supported audio: 16bit / 44.1KHz; FLAC / WAV / APE / WMA / MP3

Bluetooth audio playback

Computer speaker mode via USB input

Bass/treble tone switch

Key lock

Output power 450mw

Speaker: 4 ohm 3W

Headphone output 1/8 "Jack 300 ohms

Line Out 1/8 "jack (level adjustable for FM individually and as a group LW / AM / SW)

Antenna Aux Input Jacks for ALL Bands 1/8: Mini jack

The antenna switch disconnects both internal antennas when using external antennas

Power supply: 3.7V (18650 Li-ion battery or external DC 5V (USB Type B mini plug)

Size (Approx.) 198mm / 7.8" x 120mm / 4.7" (H) x 38mm / 1.5" (D)

Weight without battery 611 g

73, Tom, M7MCQ.