Listener's Guide

Classic Receivers From Lowe Electronics

We look back on some of the great sets from a great company.

The HF150

It was a simple joy to work on projects that became the classic Lowe Radio Range.

The HF-150 is a double conversion superhet with two IF filters, nominally 6.5 and 2.6 kHz. They are selected by mode making operation easy for the novice listener.

The AMS detector in the HF-150 is much better than in the older radio. For one thing, it allows selection of upper or lower sideband. It also hangs on to the carrier for dear life! The radio will lock on to the weakest carriers too. It's also standard equipment.

The HF-150 measures just 7.25 x 3.125 x 6.25 inches. Its case is made of heavy gauge extrude aluminium, so the receiver will take a lot of stick. The HF-150 is powered by 8 penlight batteries and a new set of alkalines only lasts about 5 or 6 hours as the computing is old tech. An AC adaptor is supplied with the radio.

The HF-150's front panel is very clear. A frequency display, tuning knob, three push buttons, a volume control and a headphone jack. One important control has been banished to the back panel; the 20dB attenuator. With no bandpass filters like its older sibling, it can be overloaded by strong signals. But who cares...

The HF-150's lack of RF input filters can cause problems when the set is operated near a powerful radio transmitter. Use of the attenuator helps considerably. With a loop antenna, active or passive, they are among the most sensitive receivers available.

Press the MODE button and the display changes to show the mode in use. You can then press the right or left buttons to move from mode to mode. The AM (A) synchronous double sideband (ASd) and Hi-Fi (ASF) modes all use the wider filter; the remaining modes utilise the narrower filter The ASd mode is similar to that found on the HF-225 and is best for normal listening. The ASL and ASU modes produce very pleasant audio even though they utilise the narrow filter. When a signal is in the clear, switching to the Hi-Fi ASF mode yields wonderful results. This mode uses the same, wide IF filter as ASd, but changes the BFO injection frequency to recover more high frequency information. Lowe rates the audio frequency response in ASF mode at 20 Hz to 5.5 kHz, about as good as AM radio gets.

The HF-150 has only one memory mode, called preview and you must press the RECALL button to tune the set to the stored frequency. However the keypad is must more useful: punching in any number between 1 and 60 and pressing the # sign will tune the radio to the frequency and mode stored in that memory. The HF-150 requires you to press only one button to store the radio's setting in a memory.

Signals from the antenna are passed through a switchable 20 dB attenuator and a 30 MHz low pass filter to the RF port of a transistor tree mixer, where the RF signal is mixed with a local oscillator to upconvert it to the first IF or 45 MHz. The first IF is passed through a PIN attenuator (for AGC) then through a 15 kHz crystal filter and on to the second mixer's input port. Here the 45 MHz signal is mixed with a heterodyne oscillator that tunes between 44.544 and 44.545 MHz in 128 steps, giving an effective tuning rate of 7.8 Hz per step. The resulting 455 kHz IF passed directly to the selectable IF filters. These filters, nominally 6.8 and 2.5 kHz are selected by diode switches controlled by the radio's microprocessor. The radio's first IF amplifier follows these filters.

The HF-150 has two IF amplifiers each feeding a separate 6.8 kHz IF filter, so there are three IF filters in the circuit at all times. The output of the IF chain is sent to an envelope detector for normal AM reception and to a product detector for SSB an d synchronous AM detection. A fixed frequency BFO supplies carrier for detection of SSB or CW signals while the BFO's frequency is varied by a control loop that's phase locked to the received carrier, for synchronous AM reception. Lowe performs a neat trick here, too: by increasing the BFO's offset frequency in the ASF Hi-Fi mode, the same IF filters can be audibly widened thus producing more treble in the output.

The HF225

The Lowe HF-225 is a double conversion superhetrodyne receiver that provides AM, SSB and CW reception from 30 kHz to 29.999 MHz in 7.8 hertz steps.

Selectivity is supplied by ceramic filters in bandwidths if 10, 8.8 and 2.2 kHz. There's a 200 Hz audio filter, centred to 800 Hz, for CW reception. Frequency readout is to the nearest kilohertz. There are two VFOs and 30 memories in the receiver to store favourite frequencies. Modes are not stored. A noise blanker is included, always on and it's not adjustable.

Lowe offers two options for the HF-225: external keypad for easy tuning and a PLL synchronous detector for AM. The AMS detector has drawbacks, but its benefits far outweigh its shortcomings. The same board is used for narrow band FM reception. When the AMS mode is in use the 10 kHz bandwidth becomes 12 kHz suitable only for local broadcasts or the clearest shortwave signals.

The HF-225 is housed in an aluminium box measuring 10 x 7 x 4.25 inches and it's built like a tank. The radio is tough, especially when fitted with the optional leather carrying case. It can be fitted with an optional NiCd battery pack and a whip antenna and impedance-matching amplifier for portable operations. The radio is powered from an external 12 volt power pack.

The HF-225 has a bank of 30 memories. The contents of any memory can be reviewed at any time without changing frequency. To transfer the memory contents to the main display, a single press of the Recall button will do just that.

In Channel mode the memories can be scanned using the main tuning knob, with the receiver tuning to each memorised frequency as it appears on the display. Extremely versatile in use, and an example of the thought which has gone into the HF-225.

All frequency information, together with the filter status, attenuator status, memory channel contents, and in-lock indication for the synchronous AM detector is shown on the main display. This is a high contrast back illuminated liquid crystal type, which gives totally unambiguous readout.

Tuning the receiver is by the well-placed tuning knob, together with the Up/Down buttons which step the HF-225 up or down in 1MHz increments. An optional keypad (KPAD-1) simply plugs into a jack on the rear of the panel and allows direct entry of any frequency from a telephone keypad layout. This is a listeners dream.

The HF-225 operates from 12VDC, and a mains power unit is included in the basic price. You can equally well run it from a vehicle battery or using the optional internally fitted B-225 battery pack you can carry the receiver around. Charging of the batteries is carried out automatically when the receiver is connected to its power supply.

If portable operation appeals, a further option available is an active whip aerial, the W-225; the pre-amplifier fitting inside the receiver, and the telescopic whip connecting to the coaxial aerial socket on the rear panel. The whip amplifier can also be used as a pre-amplifier for short wire aerials in difficult locations.

The HF-225's front panel is simple, with four knobs (volume, tone, mode and tuning) and five pushbuttons which serve multiple purposes. The frequency display is in the centre and there's a small S-meter illuminated by three green LEDs which are on whenever the radio's on. There's also a 1/4 inch jack for monaural or stereo headphones.

The set's rear panel contains an SO239 coax connector for a 50 ohm antenna, compression type connectors for a high impedance antenna, a three position antenna selection switch (Lo-Z, Hi-Z/Whip) a squelch control for NBFM, a centre positive concentric socket for the power supply and RECORD jack. Simply the best...

The Kenwood R11 Portable Shortwave Radio

If you are a high-tech company as Lowe Electronics was, what do you do when a low-tech demo receiver turns up in the hope you will sell it?

You quietly give it away to one of the technicians who is simply happy to have it, in spite of the fact it fails in nearly every aspect of receiver design.

I still have it. It is the longest surviving shortwave radio. I like it because it's anti-tech, a bit punk.

The R-11 was manufactured in the early 1980's by Toshiba for Trio-Kenwood. The radio was dumped by Lowes as it was analogue and all the competition was digital in the portable sector.

The R-11 is just good fun. It doesn't cover all of the shortwave radio spectrum, it only has the AM mode for shortwave listening, the tuning is touchy, it drifts like driven snow but the audio quality is quite good thanks to a large speaker for its size.

And such a delight on FM compared to DAB.

The volume control is a slider on the left side and is under the left thumb when holding the radio. A three position slide tone control is located just below the volume control, so when holding the radio the right thumb and index finger are on the tuning knob and the left thumb is on the volume slide.

Band select buttons are lined up across the bottom and there is a red LED above each vertical band segment on the analog dial. This provides for quick band selection and is very handy for quickly scanning the bands.

The tuning meter is a real analog meter movement.

Sensitivity is good due to a clean background absent of synthesiser noise. You see, analogue had something going for it.

This is the Smart car of shortwave radios. Too much fun to get techie about.

The Trio QR666

We sold our pristine AR88D in polished oak cabinet because we were bored. We took our new-found riches up to Lowe Electronics and bought a QR666. Why?

The AR88 was about as far as the technology had advanced in its day. The QR666 was new tech but entry-level. We just liked the look of the thing. We were about to learn a lesson or two.

It did hark back to radios of old with large illuminated dials. It did have Tonka Toy tuning knobs, one of which was BANDSPREAD. You could spread the Broadcast or the Ham Bands. It was an option. To go for the broadcast option surrounded by Hams at the local club was social suicide.

Any of those Hams would tell me of the QR666's technical failings. We knew this and we revelled in them. Selectivity was either NARROW or WIDE but the filters leaked so gloriously, AM listening was a joy.

It had the power to drive an outside hi-fi speaker. It may seem a bit of a waste but AM radio was not as processed as what's left of it is today. It did hum a bit.

We often wondered if this was noticed outside the UK. This was modulation hum, only present on the carrier of an AM station. The standard fix was to bridge the rectifier diodes with 0.01uF capacitors. At least it was a chance to try a few modifications...

Our QR666 did drift a little but the OCD that seems to go with the hobby had us at the Tonka tuning knob and back on frequency.

QR6-FM was not an exotic call sign but the FM Radio option. A must-have, it meant another trip to Lowes, always a joy as it gave you a chance to demo the radio you should have bought.

The Installation Guide said fitting the FM Option was easy. It was, because we knew how to solder, how to wire up, how to read circuit diagrams and how to check it all before you switched on. Those skills are gone now, replaced by Plug And Play and knowledge of sales law, so technical incompetence in the buyer can be blamed on the dealer.

FM was great on the QR666. More leaky filters meant the sound was cool, tuning a little less so. The over-sensitive front-end got us into Sporadic-E listening from Kenny Everett on Capital to opera from Milan.

A technical let-down on paper but great to own, we miss it now.

The SRX50

Rolling gently along the winding lanes between Idridgehay - a name for Scrabble players to bear in mind - and Cromford, I would be aware of the rear-view mirror filling up with BMW. This would wait for the least likely chance to pass and then do so, waving a cheery greeting and vanishing into the morning mist.

By the time we got to Matlock, my Bavarian friend was only three cars ahead. It seems a lot of effort, somehow.

Thirty years have passed since Dad, trying to keep the radio away from the kids, screwed same to the ceiling. In that time I think I've seen 'em all. Ex-service radios like The No. 19, 52, 62 Sets, the hernia inducing R107, AR88 and RA17 up to todays Icom, Kenwood and, to borrow from the beer advert, the reassuringly expensive Racal. For each in its time, some great performers. Today, price and performance are tightly linked - you will get what you pay for, so let's leave the high ground and wallow below. Cheap radios can be fun.

For around forty quid, you enter another world. A world of limited frequency coverage, missing broadcast bands and no SSB. At the time of writing, this sunspot cycle is in rapid decline, some broadcasters going for a mid-season change to lower frequencies in the hope of a usable signal. This means their good efforts can now be heard by those of us who drop off the radio world at 15.5Mhz.

Reception is very variable and will be for a few years yet. When it is good, it's very good, so you don't really need extreme sensitivity. When it's bad, it's bad, rapid selective fading reducing all but the very best receivers to a low common denominator in terms of listening for entertainment.

Better SSB will come to the cheap and cheerful end of the market, but if this is your forte you are best going for a base station with a decent antenna.

Filters seem an emotive subject. Down here we should be grateful we've got one. It will be middle-ranking in selectivity in an effort to be all things to all men, it's quality a reflection of the component buyer's skill. Can he get enough at the right price to be sure of reasonable performance throughout the product life?

In any event in the presence of very strong signals, it will leak allowing one of the joys of reduced selectivity, glorious audio quality. It's only fair we should ask our little radio to pick up only the major broadcasters. DX we can leave to the big boys...

Image rejection produces more emotion. The single conversion radio for the financially challenged will have an IF around 460kHz, so it will produce heaps of images where the big boys can hear aeroplanes and ships. We have no SSB, so no problem. We also know in our heart of hearts that the BBC does not use 8.5Mhz...

Battery life is important to the traveller. If you go to places where battery is teamed with assault, they may be hard to get. The best thing is a dial-and-pointer set as the battery is then running only one, maybe two, oscillator transistors. In the digital synthesised radio, the battery is running hundreds of the things, the price we pay for the convenience of key entry, memories and little glowing numbers. If possible, use the radio whenever you can on a mains power supply. Not only is it two hundred times cheaper than batteries to run, but the mains connection gives a capacitative reference to earth, helping with perceived sensitivity no end.

So, now I've made the case for simple enjoyment of the simple receiver, let's we what the wild waves are saying. Korea on 6560kHz, China on 7780kHz and good old Australia on 13755kHz and even a clock to tell me that it's time to close. The race, it seems, is not only to the swift. Or BMW owners.