VK3YE amateur radio pages

QRP Equipment

 

All material on this site (c) Peter Parker VK3YE
1997-2014.

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FT817 R4020 QRP rig

There is a wide range of equipment available for the QRPer. This includes 100 watt transceivers than can be wound down to QRP, purpose built QRP and portable radios, build-it-yourself kits and building gear from scratch. Keep reading if you want to know what to buy or build and get results with QRP.

QRO equipment wound back to QRP

Today's 100-watt transceivers can often be wound back to deliver QRP power levels. Their multimode multiband coverage and other features make them attractive to the operator who wishes to try QRP but also retain QRO capabilities.

A particular benefit is their impressive array of interference-beating features, such as noise blankers, notch filters, variable tuning rates, IF shift and digital signal processing. For this reason, this gear provides excellent results when trying to receive marginal signals from distant QRP stations.

What are the disadvantages of using 100 watt transceivers? Compared to dedicated QRP radios they are bulky, heavy and draw high currents on receive. It is not uncommon for a modern HF rig to draw 1 to 2 amps just on receive, ie more than what most QRP radios on transmit. While not a problem for home use, this last factor alone makes large transceivers a poor choice for portable work due to the weight of batteries required.

R4020

Commercially-available QRP equipment

When QRP first took off in the late 1960s, spurred by the increasing availability of solid state RF devices and the rediscovery of direct conversion receivers, a number of American manufacturers produced equipment specifically for QRPers.

Heathkit produced the HW7/8/9 series of CW only transceiver kits during the 1970s and 1980s. Of these the HW7 drifted and had a poor receiver, the HW8 was a much improved design and is still recommended while the HW9 had more bands and mixed reviews.

SSB QRPers of that era could buy Ten Tec's Argonaut 505, 509 and 515 models. Though lacking today's refinements, they performed well and are still sought after despite their large (and not particularly rugged) enclosure, crude tuning dial and odd choice of power and antenna connectors. $200 to $250 is a fair price on the used market for a working Argonaut 509. Ten-Tec continue to produce and market QRP gear, some of which will be discussed later.

Japanese QRP rigs, designed for their 10 watt novice licence, were imported into Australia in big numbers and frequently appear secondhand. Examples included the Yaesu FT-7, Yaesu FT-77S and Kenwood TS-120V. These rigs are still good performers, but lack 160 metres, some HF bands, and digital signal processing found on newer transceivers. They are bulky by today's standards they are bulky and are best suited for home or car use. Their used price has risen since the advent of the Foundation Licence; expect to pay around $200 to 250 for one.

Less well known QRP rigs of the 1980s include models by Shimizu Denshi, MFJ, Mizuho and the ironically-named Tokyo Hy-Power. These may only cover a single band and be CW or SSB only. They also had analogue VFOs and dials.

The first 'modern' QRP radios, with all-HF coverage, digital dials and CW/SSB modes were the 'cube' Index Labs QRP Plus and the rugged SGC-2020 transceivers. These came out in the 1990s. There was also a blossoming of QRP kits from various US QRP clubs, including from designers who would later form Elecraft (discussed later).

Mainstream ham manufacturers reentered the QRP field from the early 2000s. Possibly the longest running and most successful QRP transceiver ever is the Yaesu FT-817 (pictured above). Unlike previous QRP rigs, the '817 operates on all bands between 1.8 and 450 MHz and has a compartment for optional internal batteries. It provides 'big rig' performance in a tiny package and has provoked renewed interest in back-pack and pedestrian mobile operation. The FT-817 came out in 2001 and is still a current model as the slightly updated FT-817ND.

Icom came along with the IC-703. This is a HF/6 metre ten watt version of the popular IC-706. It is larger than the FT-817, has fewer bands but some may find it less fiddly to operate with larger knobs and screen.

Smaller companies remain active in the QRP business. Most prominent is Elecraft which dominates the high end of the QRP market. It started with CW transceiver kits but also now carries CW/SSB kits, modular kits and prebuilt transceivers. Its most popular current offering is the KX-3 which vies with the FT-817 for popularity. This HF transciver costs more than the Yaesu, has fewer bands and is less physically rugged. However it offers 'big radio' performance and is more power efficient. It is widely regarded as the best portable HF QRP transceiver ever produced.

The Chinese have lately been very active with QRP equipment, both under their own brands (such as YouKits or Xiegu) or rebadged as American brands (such as Ten Tec). Prominent models include the Xiegu X1M (HF SSB/CW), The Ten Tec R4020 (40/20m CW only) and the KN-Q7 (40 or 20 metre VXO SSB only).

Quality, reliability, finish and customer service varies, especially from the newer manufacturers. It's always a good idea to to read reviews on sites such as eham dot net before purchasing.

homebrew

QRP kits

QRP constructors have a variety of kits from which to choose. These range from no-frills crystal-controlled transmitters to multiband CW/SSB transceivers. QRP kits can be club projects for members or be available on the commercial market. Some are even designed and produced in Australia. The results obtained from a good kit on the right band make this choice worthwhile, especially if less experienced or time-poor.

Things to think about when choosing a kit include:

* Modes and bands provided
* Whether the output power and receiver performance are sufficient for routine communications
* Whether it is fixed frequency or frequency agile
* Whether it is complete or short-form (ie board and parts only)
* Whether it is transmitter only, receiver only or transceiver
* Complexity of construction and experience required, including use of surface-mount parts
* Whether you think you can build it (see supplier websites for instructions)
* Reputation of manufacturer and reviews by others who have built the kit

Avoid both extremely simple and extremely complex kits unless you're experienced and know what to expect. Most people find there is a 'sweet spot' where kits are neither too expensive nor complex yet achieve many contacts.

Bare bones 'minimalist' kits (such as the well-known Pixie series) have rudimentary receivers, weak transmitters and a fixed operating frequency. Getting contacts is frustrating because other stations must find you rather than you find them. They may use only three or four transistors and only put out a few hundred milliwatts. Transmit output filtering, keying quality and receiver selectivity may also be compromised.

Only attempt this type of kit if you are looking for a novelty project or are willing to call for long periods between contacts. Alternatively build the circuit from scratch, not using a printed circuit board. That gives flexibilty to add improvements. If your heart is still set on buying a kit, pay that little bit extra and get one that will be a pleasure to operate for years to come.

What are good candidates for a first-up QRP kit?

Single band is preferred as more bands means more complexity. Select a popular band that will be open throughout the solar cycle and produce contacts at the times you plan operating. Don't rely on reports from overseas - activity here is less, and a minimalist rig that will get contacts in more populated countries may work less well in VK/ZL.

40 metres is my recommendation, providing easy and regular communication up to approximately 1000 kilometres. 20 metres has the added excitement of working DX but contacts are much harder to get and there are fewer conversations between VK stations. 80 metres is good if most of your operating is at night, though voice is preferred over CW due to higher activity.

Higher HF bands like 17 to 10 metres offer great DX opportunities but do not open frequently enough for them to be your only band.

Transmitter output power should exceed 1 or 2 watts. Anything less is frustrating. A kit with a BD139 or IRF510 final transistor should put out enough power whereas one with a 2N2222 will be too weak.

A degree of frequency agility is essential. A modern DDS VFO will cover all the band but only comes with the more elaborate kits. If a kit has a digital frequency display the chance is it also has a DDS.

A second and simpler choice is a well built ceramic resonator or wide swing VXO with two crystals and a good variable capacitor. This can cover a worthwhile section of band. A ceramic resonator can span 100 to 200 kHz while a wide swing VXO should cover 15 - 50 kHz. Kits that use varactor diodes and potentiometers for VXO tuning may cover a lesser range than those with air spaced variable capacitors.

Check that supplied crystals or resonators suit local activity before buying kits that only cover a band segment. For instance US QRPers generally use higher frequencies than those in most of the rest of the world on 80 and 40 metres. A 7040 kHz crystal, for example is fine for various digital modes but not for CW. Similarly SSB/DSB rigs need to tune below 3700 or 7200 kHz as that is where most activity (and in some cases frequency allocations) are.

CW transceiver kits are available from suppliers such as Ten Tec (1340, 506 Rebel), Hendricks (PFR-3A) or Elecraft (KX1 or K1). Any of these would be an ideal for trips and draw less current than prebuilt commercial rigs.

The simpler SSB kits are normally either discrete component based (eg the BitX) or use NE602 mixer/oscillators (eg the Chinese KN-Q7 MST series from OzQRP). All are established designs built by Australian constructors. The VXO-controlled KN-Q7 is the simplest while the more advanced MST covers all its band. The BitX is open source and several suppliers offer boards and/or full kits. Search YouTube for demonstrations of all these kits.

Multiband QRP transceiver kits represent a step up. They are recommended for more advanced constructors only. They have become more prevalent thanks to wide-range DDS VFOs and put the assembly of multiband gear within reach of more. Some of the CW transceiver kits cover several bands while Elecraft offer multiband HF CW/SSB transceiver kits.

If a kit radio appeals but you don't want to build it check to see if the manufacturer offers a pre-built version. This option would also suit Australian Foundation Licence amateurs who cannot legally make their own transmitter.

Another option is to scour the hamfests and second hand ads. Brands to look out for include Heathkit, Small Wonder Labs, Hendricks, Oak Hills Research, Elecraft and OzQRP. Information on these is widely available on the web.

You'll also find reviews of prebuilt and kit QRP rigs on eHam, while some have their own email list.

bitx

Homebrew QRP equipment

QRPers also have the option of building their own rigs. And a surprising number do. Homebrewing is the way to go if you want a rig that is personalised to your interests and preferences. For example, you may require a particular band combination and an unusual ability to switch audio bandpass and notch filters for best reception. A homebrew rig may also be a platform for development of a high performance receiver, or novel transmitter arrangement, for example.

Some general components for homebrew transmitters and transceivers can be obtained from the usual parts suppliers, while the more specialised parts (toroids, variable capacitors, NE602s, etc) can be found at amateur hamfests, junk sales, eBay or purchased by mail from QRP clubs or specialist online suppliers.

Transmitter or Transceiver?

A key decision for the constructor is whether to construct a transmitter or transceiver. A transceiver is easier to operate and less bulky - major advantages for portable operating. However a transceiver is more complex, especially where many stages are common to both the transmitter and the receiver.

A transmitter is recommended over a transceiver for the beginner as it uses fewer parts and is easier to troubleshoot. In many QRP transceivers, the receiver may account for two-thirds of all components used. Leaving out the receiver makes for a simpler and quicker project that is more likely to work first time. Also, the use of an outboard receiver means that the transmitter/receive frequency offset circuit can be dispensed with, further simplifying circuitry. Another point in favour of the separate transmitter/receiver approach is that most QRPers will already have a suitable communications receiver available. The performance and ease of use obtained will typically be better than that from a simple homebrew receiver.

A good plan is to build the transmitter in an oversize box. Once the transmitter has been got working, it can be expanded. For instance, a direct conversion receiver can be added. Or an extra band. Or, maybe even the parts required to generate a DSB or SSB signal.

Choosing a design

What type of transmitter circuit should you start with? Sure, it's very easy to build a simple 80 metre QRP Morse Code rig. Just one or two transistors and a 3.58 MHz TV colourburst crystal, and you're on the air. But will the rig sound OK? Will you get contacts? Or will the rig cause you to give up QRP because no one is responding to your CQs?

This website is devoted to practical QRP. QRP that works. QRP that's fun. And to get the most enjoyment from QRP, you need to know something about the capability of your equipment so that you don't expect too much and become disappointed when your hopes do not materialise.

Be selective about the type of QRP rigs you build. It must be fairly simple and not require too many hard to get parts. Secondly, it must be put out enough power to be heard on the air. Thirdly, it should be frequency agile over at least a segment of the band. The following sections explore these points in depth. The author's minimum standards for homebrew rigs should also assist the builder to cull the good from the useless in the hundreds of circuits available.

Power

What is sufficient power? Though this depends on the distances you wish to work, I would say that an inexperienced amateur aiming to make regular contacts with powers of less than one or two watts on any HF band is going to be disappointed. Sure those milliwatt rigs you see described in foreign magazines and on the web do work, but remember that Europe and the USA have far more amateurs per square kilometre than we have in Australia. As it's so easy to build one or two watt transmitters that there is little sense in settling for less unless you specifically want to do experiments in milliwatt communications.

I would recommend powers of 1-2 watts as a practical minimum assuming you are using a reasonably efficient antenna (eg a full-sized dipole). Though there will be times when more power than this will be required (eg when static is bad), you should be rewarded by reasonably frequent contacts up to several hundred kilometres, and the occasional two or three thousand kilometre contact with 1-2 watts. On 40 metres 1 - 2 watts is again sufficient for distances of up to about 1000km, and the proportion of Q5 signal reports tends to be higher than on 80.

On 20m and up, Europeans and Americans can regularly be worked at the 2-watt power level, especially if portable overlooking water. Don't expect reliable DX contacts from home with this level with low dipole or vertical antennas, however.

PSK-31 is a highly effective mode, and long-haul DX almost every day is quite possible with 5 watts and an indoor antenna.

SSB requires more power for comparable results, but even so 5 or 10 watts can be rewarding, even in the middle of the 20 metre 'kilowatt alley'. Very low output powers can be very successful on the higher bands, but you need to be there at the right time - the kilowatters may enjoy DX for hours, but the QRPer must be there when the band is optimum.

Frequency agility

Then there's frequency agility - being able to move around the band, rather than being stuck on a single frequency. Most home brew QRP transmitters are crystal-controlled. Most of them also sit on the shelf gathering dust and are seldom used. Why? Being locked on one frequency severely hampers your operating success. You could be calling CQ, but not be getting any replies. Then 5 kHz up the band, you hear another station also calling CQ. If you were frequency agile, you could move to the other station's frequency and most likely obtain a contact. Instead, you remain on your frequency, hoping that the other station will not get a reply, stop calling, tune around and eventually find you. A lot of people build simple rigs, have one or two contacts, and not use them again because getting contacts is sheer hard work.

The disadvantages of crystal control are greatest with QRP. Unless someone happens to start calling on 'your' frequency, the only way to get contacts is to call CQ yourself. As many people tend to reply to CQs from stronger stations only, your chances of getting a reply are reduced if your signal is weaker. The successful way to get contacts with QRP is to 'search and pounce'. Either reply to CQ calls from other stations (you know at least someone is listening for your call), or 'tail-end' contacts that are concluding. Both of these techniques are only really possible if you can move frequency. And, if there is not much activity around, and you do wish to call CQ, chances are better if the call can be made on a perfectly clear frequency. The probability of finding such a frequency is of course much greater if you can operate everywhere in the band.

Another limitation of crystal control is that your crystal may not be in the most active part of the band. For example, 3.58 MHz TV colourburst crystals are conveniently in the middle of the 80 metre Novice allocation. However, most CW activity is below 3.550 MHz. Operators seeking CW contacts will not often be tuning across 3.58 MHz. So, the chances of getting a response are reduced as you are not where most potential contacts will be listening.

Even crystal-control on the so-called International QRP Frequencies (eg 7.030 & 14.060 MHz) can be very limiting, at least in VK/ZL. These frequencies are sometimes clogged by strong digital mode QRM, and are made useless as a result. This disadvantages the constructor who has built a rockbound 'OXO' or 'Cubic Incher' rig that is stuck on the single frequency. Though authors describing such projects invariably report great success with their one or two transistor creation, bear in mind that they in Europe or North America, where the amateur population is at least 20 times Australia's. Attempts by Australian amateurs to operate such transmitters often lead to fruitless CQs, followed by grave disappointment with the lack of contacts achieved.

To summarise, because 'search and pounce' (answering calls and tail-ending) is the best way to get contacts, frequency agility is essential for the QRPer. Use nothing less than a VFO, good VXO, or stable variable frequency ceramic resonator oscillator to succeed with QRP.

Mode

Morse transmitters are the simplest to build. A simple VXO CW transmitter can be built in an afternoon and work stations near and far. Watt for watt they are more efficient for longer distance communication, especially on crowded HF bands like 20 metres.

If you are building a voice rig, should you choose AM, double sideband suppressed carrier (DSB) or SSB? An SSB rig is a challenging project, and is not recommended unless you've already built CW and DSB transmitters. So, for the newcomer (and even for many experienced amateurs), the choice is between AM and DSB.

AM was used prior to the advent of SSB, and still has a following on some bands (especially 160 metres, to a lesser extent on 80 and 40). However, many SSB rigs do not have AM and it may not always be easy to resolve a weak AM signal on an SSB transceiver. Because AM signals include a carrier that does not contribute to the intelligibility of the signal, AM is less efficient than SSB, and more transmitting power is required to make oneself heard. However, AM still has its uses. The speech quality of AM is generally better than DSB or SSB. Where you have a small group interested in local contacts only (such as within a country town or small city), a homebrew AM rig would be a fun project, particularly on 160 or 10 metres where there is plenty of band space. Ranges of up to about 5km can be achieved with powers of under a watt.

DSB has an equivalent bandwidth to AM, but has no carrier. Thus it is a more efficient mode. As well, DSB is fully compatible with modern SSB equipment, and unless you tell them, many SSB stations will not know that you are using DSB. The combination of a direct conversion receiver and DSB transmitter is highly recommended for the Novice wanting to build an HF voice station, and because of the similarity of DSB and SSB. Also, DSB transmitters can later be upgraded to SSB by adding extra circuitry. DSB is particularly recommended for bands such as 160, 80, 40 and 10 metres due to the ample space on these bands.

For the experienced homebrew constructor, SSB is undoubtedly the most rewarding voice mode as it's the hardest to build a transmitter for. The builder is entitled to take personally the reports of outstanding audio that accrue as the transmitter is all his own work. Also transmitting your voice (and not just dots and dashes) over 20 000 kilometres with a transmitter you built yourself is a thrill hard to describe.

Minimum standards for homebrew rigs

The following are sensible minimum standards for any homebrew or kit QRP rig you build. My experience is that all must be followed to have successful and enjoyable results with QRP.

1. Power output at least 1-2 watts

2. At least some frequency agility in a popular part of the band

3. CW and/or DSB/SSB operation.

If you see any design or kit that does not meet the above, have second thought about building it, even if it appears cheap and simple. Even if it works according to the book, you will soon become disappointed with is limitations.

Meeting the minimum standards for homebrew rigs

1. Power output

Look for a design with a reasonable power output transistor. A BFY51, 2N3053, 2N3866 or 2N4427 in the transmit final stage should have an output close to 1 watt. 2N3553, BD139, IRF510 or IRF511s are all capable of power outputs between 2 and 4 watts. Two lower power transistors can be wired in parallel (with suitable emitter resistors) to produce more output. A 2N2222, 2N3904 or BC548 as the final amplifier is a sure sign that the rig is nowhere near powerful enough.

2. Frequency agility

A free-running VFO or synthesised VFO usually provides full band coverage, but can be difficult for the newcomer to get going properly. It is not always easy to obtain good frequency stability in a free-running VFO on the higher HF bands, and synthesisers tend to be somewhat complex to build. Nevertheless, a free-running VFO is a good choice for an 80 metre rig provided that care is exercised in its construction.

Cheap ceramic resonators are a good choice on the lower HF bands due to their handy frequencies. A resonator for 3.58 MHz can be swung over 100kHz while a 7.2 MHz resonator can cover 200 kHz. Both tuning ranges span active portions of the voice parts of 80 and 40 metres. This makes them particularly suitable for DSB transceivers, and on 80 metres, CW rigs as well.

Quartz crystals are not recommended on 80 metres as they cannot be shifted very far in frequency. However, at 7 MHz and above, crystal oscillators (VXOs) can be pulled to provide worthwhile coverage of frequencies immediately below the crystal's nominal frequency. Ranges of 5 to 15 kilohertz can be achieved, depending on the crystal type and the operating frequency. Connecting two crystals in parallal can double pulling range. VXOs are particularly useful for CW/DSB equipment on 40, 30, 20, 17 and 15 metres. However frequency multipliers are required on 12 and 10 metres because of the inability to shift crystals very far when used in their overtone mode.

3. Mode

Watts are precious so it pays to use an efficient mode. Contrary to views expressed by many northern hemisphere QRPers this definition need not be confined to Morse or digital modes.

With perseverence good results are possible on SSB at QRP power levels. And DSB can be practical on QRP friendly bands such as 40 metres.

You can recognise a DSB or SSB design by the presence of a balanced modulator stage in the circuit. This is required to null out the carrier that would otherwise be transmitted (as it is on an AM signal). Devices such as the NE602 (also used in direct conversion receivers) can be used. Older designs use other ICs (CA3028 and MC1496) which are less available now. More recently there has been a swing back to two or four diode balanced mixers due to their good performance and low cost.

Like in an SSB rig, power amplifiers used in DSB rigs have to be linear. This means that a power amplifier circuit used in a CW transmitter is normally unsuitable for DSB unless its operation is made linear. Luckily the same output transistors as in CW rigs can be used but efficiency will be lower.