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mike48
3rd April 2012, 12:04 PM
Radio Receivers for the Shed or Workshop – Choosing a Radio, and Reception Improvement
Some things to look for in radio choice –
1 – AC mains operation primarily, or the ability to use a plug pack.
2- Large loudspeaker(s) for better sound quality.
2a – Large loudspeakers!
3 – Large operating knobs or sliders for easy operation, if you have to tune often.
4 - Tuning indicator, and Automatic Frequency Control for FM ; (most will have it).

For marginal reception areas, add
1 – Tuning with a knob may be better than a push button type (better tuning feel).
2 – External antennas for both FM and AM (different) if required

Suggested suitable receivers –
Car radios are ideal, especially for marginal reception areas.
They are very sensitive, have good audio quality and power, and easily allow use of a single external antenna and radio ground for both AM and FM. They also have good overall shielding against nearby interference, and have a filtered 12V supply input circuit to reduce some other forms of interference.

They can be powered from a 12V plug pack (choose larger current rating rather than smaller, otherwise you may get audio distortion due to “voltage sag” on audio peaks).

Sometimes a car antenna should not be too long (as it is effectively “tuned” in the receiver). Better to use a car radio antenna extender cable, feeding a commercial vertical car radio antenna, attached to the shed roof or gutter.
Remember to add an earth from the car radio metal case to an earth stake driven into the ground, away from mains earth stakes.

Do not use mains power earth stakes under any circumstances.

Some car radios need to have their antennas “tuned” with a tiny screwdriver type adjustment on or through the front panel or on the radio side. Refer to your handbook. This antenna tuning is important and really affects reception.
Most radios tune the antenna at the high end of the band. Modern car radios sometimes don’t have this, as it is automatic. You can sometimes find old HiFi loudspeakers in enclosures to suit, at markets at very low prices, or as roadside cleanup junk.

Match the receiver and loudspeaker “impedances” for best results, but don’t worry too much.

Don’t worry about sound power. One watt of Dire Straits music in a house sized garage will be quite loud.

And don’t worry too much about audio distortion.
Except in lab type situations, you won’t hear 1% THD, and in a working shed, you probably won’t hear 5% on music, nor hear 10% on voice.
You can use “figure eight” type cable or similar to connect your speakers.

Don’t fall for the “Oxygen Free” cable spiel; it is just a waste of time and overkill for all but the most exceptional cases.
Better to have more copper in the cable, than oxygen free copper cable.

If you reuse old PA type speakers, connect to the internal speaker tabs, not to the external connectors.

Modern portable medium size receivers such as Sony ICF703, ICF704, Panasonic RF2400, etc which have quality build, and have relatively sensitive receiver front ends, are AC/DC, and have reasonable size speakers. I use a Sony ICF703 as an excellent campfire AM/FM radio on travels in the outback, placed on the ground and with a four metre clip on wire antenna for improved FM, if service is available.

Don’t waste your time on pocket radios, which are city receivers, mostly have poor sensitivity and small speakers.
Similarly don’t bother with iPod mounts or later Sony walkman type pocket receivers.

Some people use portable mini communication type receivers such as the Sangean types, and some of these have external antenna connections for AM as well as FM. However these invariably have tiny speakers, and would benefit from an external speaker.

Older Cassette/CD/Radio combo units (boom boxes) can be quite good.
I currently use an old Sony Cassette Radio in my garage with two 4 inch speakers and have connected an extra antenna via an alligator clip to the FM rod antenna to listen to Brisbane Bayside BAYFM 100.3 Mhz, a good mix of old, very old, and new. It is a bit weaker than stronger commercial stations, and I have aluminium foil insulation all around in the house walls, hence the need for an “external antenna”. I picked up this radio for free as roadside cleanup junk.

Old (really old) AM valve radios normally have larger speakers than modern portables, but probably won’t have FM. Sometimes they have connections for external antennas and earth, which can provide better reception than a modern portable with ferrite rod antenna for AM. There is always the problem of repairs which may be daunting and prove a problem (unless you are old like me). My kitchen radio is a HMV Little Nipper valve AM unit, but it only has an external antenna connection (uses a capacitive earth connection to the mains wiring), and for marginal reception areas would benefit from an “Earth” connection.
Most mantle valve radios are like this.
Console valve radios may have both antenna and earth connections.

If you have a choice of older valve radios for marginal reception areas, look around inside and choose one with three sections to the tuning capacitor thingo (with multiple aluminium vanes) rather than one with only two sections. This probably will give better sensitivity for weaker stations, all other aspects being equal.

Mini HiFi systems sometimes have separate connections for AM antenna and earth, and another set of separate connections for FM antenna and earth (suitable for say coaxial cable and TV type antenna used on FM). They may have better sized loudspeakers, and can be found cheaply at markets or as roadside household junk.

Communication receivers are good but are overkill, and will have sound quality more suited for voice than music. I have a JRC NRD515 and an Eddystone 1830, but they provide only marginal improvement over say a modern car radio on AM, do not have FM, and are too valuable to have paint spatter and accidental damage, not to mention that they are large.

DAB radio for the workshop is fine if you have coverage and a good sound system and speakers to take advantage of the high quality. DAB is mostly only available in the bigger cities. Otherwise FM is good for portable radios etc and you cannot tell the difference in quality to DAB in small units. If you have a portable DAB receiver with one small speaker, it will sound tinny, be in monaural only (no stereo) and sound worse than a portable FM receiver with a larger speaker. Tell all your rellies not to buy you a DAB unit as a novelty present for the workshop (or kitchen), as it is mostly a waste of time and money. DAB in a car, or in the lounge with a system, that is completely another scenario.
My opinion based on a Pure One Classic, which sits on top of my Little Nipper. The Nipper is invariably used most of the time, and left on AM Radio National, my favourite station whilst cooking.

If you are in a city with access to FM subcarrier programs such as Brisbane 4MBS Silver Memories, this may provide some old time favourite listening, but it is a special FM radio receiver.

Improving Reception
If you have a portable receiver such as the Sony or Panasonic units mentioned before, then FM reception can be improved by connecting a length of wire to the external antenna. Keep the antenna wire away from fluorescent lamps, CFLs, dimmers, motor controllers, PCs, touch lamps, VFDs, speed controllers, and most things electrical. Ensure that it extends outside a shed or workshop somehow, and reasonably high.

No need for an FM “long wire” antenna to be more than four metres long, and keep away from anything metallic, and away from trees etc. It may be better used on mains or a plug pack as this may provide a capacitive “earth”. Experiment.

If you have a receiver or mini HiFi with FM antenna and earth connectors, then you may like to use an external dipole. This is the little FM antenna sometimes found included with mini HIFI systems, and looks like a “T” piece of wire, sometimes fabricated from what looks like old fashioned TV ribbon feeder. These antennas perform best if outside in the open, as many sheds and workshops will have the shielding effects of metal walls or roofs, or foil type insulation.
Alternatively you can use a dedicated FM antenna, or TV type antenna which is made for, or includes, channel 5 frequency. Feed with TV type coaxial cable, and at the receiver, connect the inner conductor to the ANT connector, and the shield to the ETH connector. HiFi systems unfortunately sometimes have “metropolitan” receivers, and may not be as sensitive as a portable radio.

Probably better not to couple into your house TV system, but rather use a separate dedicated FM radio antenna. It may work OK in some situations, but introduce other noises (TV power supply and whistles) into your AM and FM reception and make it worse. Experiment.
If you get a slight tingle from the radio rod antenna from such a coupled system, don’t use it. (This is back feed from the TV, via its antenna connection, and may indicate a problem).

If you have a portable receiver such as the Sony or Panasonic mentioned before, then AM reception can possible be improved marginally by wrapping ten turns or so of thin insulated wire around the whole receiver and connecting one end to a long external wire antenna, and the other end to a ground stake (do not be tempted to use an electrical earth, as this is unsafe).

This doesn’t work in a lot of cases (the coefficient of coupling is too small), but is worth a try.
The only time I have had success was with an old larger 1972 vintage Sanyo unit, and probably because the internal ferrite rod was the older large 9 inch variety, allowing at least some signal coupling.

These AM receiver types use an internal ferrite rod (or flat bar) antenna with an internal wire loop, and are optimized to receive the “magnetic field” of the radio wave, rather than the “electrical field” as used by say old fashioned valve mantel radios and car radios, and their antennas.

This makes them “ground independent”, and they do not require a discrete earth connection, but that in itself makes reception improvement difficult without opening the receiver.
You can wind say six full turns of thin insulated wire around the internal ferrite rod and connect an earth to one end and an antenna to the other end to improve reception. Wind the coil on the end of the rod away from, and not over, the original winding.

This works in most cases with moderate improvement.

Don’t add too many turns onto the rod; more is not better, as you may change the tuning calibration, and may suffer overload problems.

Don’t think of soldering an external antenna onto the AM receiver coil on the ferrite rod, as it invariably does not work as well as the extra coil (over coupling, and may change the radio tuning calibration).

BUT, once modified, the receiver can only be used on batteries or with a plug pack, as you have “performed work on an electrical appliance”, and cannot connect to mains, unless you are licensed.

Adding an external wire antenna to the rod antenna of a portable radio to improve reception will only work for FM (and SW if fitted), as this rod antenna is not connected internally for AM use, for the vast majority of radios. You can modify a receiver to couple the AM and FM receiver sections together internally, and use the rod antenna for both bands, but you will only get AM reception improvement if you use a separate earth connection and a ground stake.

Some receivers such as a mini HiFi systems use small external wire loop antennas for AM, and you can experiment with optimum placement. You probably will find that these receivers will not give improved reception with a traditional long wire, but experiment. They really are mostly “metropolitan area” receivers. (Most have receiver circuits such as a Synchrodyne and single chip receivers, requiring higher signal strengths for even modest reception).

Experiment with antennas, length, height, orientation for your own situation. Keep away from overhead power lines and mains wiring, and allow for high winds blowing antennas onto danger areas.

Keep your antenna well below the highest metallic object in the immediate vicinity (lightning). Use stranded copper wire for long wire antennas if possible, and make insulators if required from short sections of scrap PVC tube. Don’t use wood; it is not as good as PVC in the wet, and is not self washing in rain.

If you live way from the coast, the ability to ground your long wire antenna when electrical storms are around may just save your radio from discharge destruction. Nothing like a western storm for spectacular “fireworks” around wire antennas (everything is so very dry just before it rains).

Sometimes a very long antenna will provide funny squeals and station interaction (receiver front end overload) and reception may benefit by reducing antenna length. There are also “night effects” which can be moderated by reduced antenna length.

AM long wire type antennas or car radio antennas are marginally better in the vertical, or sloping sense. AM long wire antennas in remote areas are better longer than shorter, but do not need to be longer than say 20 metres.
AM loop antennas are best with the plane of the loop at 90 deg to the transmitter site.

Ground resistance (eg granite or rocky soil can be a poor radio ground) can be a factor in AM marginal reception areas, by reducing/attenuating the radio waves near the ground surface. Hard to improve, and professionally is partially achieved by a large “in ground” system of copper wire simulating an earth. Maximise your FM reception instead, as it is less affected, although in the open, an FM portable performs better if placed on a sheet of metal, or camp BBQ etc, simulating a partial earth system.

FM stations normally transmit with mixed polarisation (orientation of the two radiated fields), so a vertical wire or a horizontal TV type antenna for FM are both OK polarisation wise, but the TV type antenna will need to be “facing” the transmitter for best reception. An exception (only for FM) to this is sometimes found in a valley situation, where signal “bounce” off hills is experienced. Experiment with direction.

A vertical wire type FM antenna is a good compromise for simplicity and cost, but a TV type antenna may be better for marginal FM areas.
Some websites below for further reading and to see what ABC stations are available in your area. (I have heard that there are “Commercial Stations”, but I have never verified this!).

Now, what have I forgotten?
Hopefully of some help to some.

Cheerio, good reception, mike

ABC Radio (and TV) Stations - http://www.abc.net.au/reception/freq/ (http://www.abc.net.au/reception/freq/)
ABC Reception Advice http://www.abc.net.au/reception/radio/listen.htm (http://www.abc.net.au/reception/radio/listen.htm)
http://www.abc.net.au/reception/radio/troubleshoot.htm (http://www.abc.net.au/reception/radio/troubleshoot.htm)
http://www.abc.net.au/reception/radio/common.htm (http://www.abc.net.au/reception/radio/common.htm)

chambezio
24th May 2012, 11:11 PM
Yes it works!!!!!!!!!!
After reading all the information which nearly smothered me......I found an old UHF TV antenna (looks more like a fridge shelf) and some 75ohm cable (left over from fruitlessly trying to receive free to air TV) welded up some RHS to mount the aerial on the shed connected up the cable and.....I now have local FM reception that doesn't drift in and out with the wind. They play easy listening music that makes a good background white noise for my tinnitus ears. Thank you for the pearls of wisdom that were shared here.

Robson Valley
31st May 2012, 09:00 AM
Thanks Mike. Most useful AM/FM information.
McBride is a mountain village, seems like the very back of beyond, most days.

I hope you get satellite radio some day soon. The antenna is 3cm diameter and looks at the eastern sky (for my location). Indoors, the unit decodes 120 channels of music, sports and talk. I set my Sirius Sportster R (90 minute memory) to rebroadcast on 88.1 MHz FM. It has enough power to reach into the neighbors houses. No rcvr antennas needed. No advertising at all. Mind you, it's about $15/month subscription but that's 120 channels to pick from or nothing at all except for night time skip.
As you have suggested, most of my home rcvrs are recent vintage car radios, couple of speakers and a 12VDC power supply - good to go.

Cliff Rogers
31st May 2012, 11:14 AM
My shed sound system is an old PC with TV & FM cards installed.
(No AM 'cos were I am I get heaps of FM & some Digital Radio as well)

I also have several Gb of MP3 music loaded.

The PC runs Win XP & the most expensive thing on it are the $70 speakers.

I can turn them up loud enough to hear the music with my ear muffs on & it doesn't distort.

I have a $35 TV antenna on the roof & an FM antenna hanging outside on the wall.

mike48
15th October 2012, 02:29 PM
Hi Chambezio,

I have been away overseas away from internet for many a month and am just catching up on posts.
Good to hear about your success with reception.

By the way, as an aside, I just have to mention that your "fridge shelf" TV antenna is probably a "phased array" type, and is in my opinion by far and away the best all round UHF type multi-channel TV antenna for the size and cost, for medium coverage areas. The better performers have three or more "bow-tie" type element things, with some having eight.
These antennas keep being rediscovered and reinvented by experimenters, who call them "magic antennas", but they have been around since the 1930s for FM and TV.

Over the last two weeks, I took my new(ish) 4WD into some remote(ish) SE and Central Queensland National Parks (Expedition, Blackdown, Kroombit, Carnarvon, Isla etc)and found, again, that an extra three metres of antenna wire clipped to my campfire portable radio antenna (Sony ICF703S AM/FM/SW) improved FM reception remarkably.

Radio National to my delight was available in most areas on FM; what a great radio station!

cheerio, mike

Robson Valley
15th October 2012, 04:00 PM
In the bush in northern Canada (nearest road = 75 miles away), we ran 25m insulated copper wire to an insulator up in a tree.
The other end went around the little transistor radio, 3 turns, then down into the wet earth.
The idea was sort of an induction effect with the little ferrite loop antenna in the radio.
I can still recall how effective that was (2, 4, 5 turns not as good).
Your milage may vary.

LGS
15th October 2012, 05:12 PM
I just fire up the Bose and use the remote for everything.Sub woofer really helps and the little speakers are safely tucked away on top of the shelves. I've got a surround sound amp as well, but just haven't got round to putting it all together. Don't have a TV, but don't really miss it. It's only 4 metres to the house.

Regards,

Rob

vk4
19th October 2012, 08:15 AM
Here's what you need to listen to all those SHORTWAVE RADIO STATIONS you listened to as a kid.

237398

I am a ham radio operator, and these have their own shed / room.

Jeff
vk4