Shortwaves are fun too !

Discuss radio from around the world. FM/AM/SW ...whatever the wavelength!
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SamTheDog
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Shortwaves are fun too !

Post by SamTheDog » Wed Apr 03, 2019 10:42 am

Hi All. Many years ago I played about with VHF-FM / band II. And I still have transmitters for FM here.
along with some mediumwave kit. But I get the most out of the HF shortwave bands. Most people are
put-off by the lack of local listners, and yes you won't get the same local-area coverage per watt as your
VHF FM kit BUT you will get some amazing long-distance reception reports even with a low-power rig.

OK the aerials are very long and clumsy compared to the di-poles and co-linears used on VHF. I use wire-
di-poles and convenient-structures for shortwave. and a 50-foot vertical for mediumwave.

My home-made transmitters regularly get-out all over europe and beyond. I still have some valve-based
transmitters of between 35 and 48 watts. and transistorised / FET transmitters of 20-250 watts.

During the mid-late 1990's and early 2000's I did some work for FM pirates. They were mostly aiming at
getting people into raves, so shortwave would not have been suitable. but later on in life I find that I enjoy
popping-up on various frequencies "for fun" and with TOR-Radio I add the shock-value by playing very
off-beat anarcho-punk in amongst the metal and blues. There is far less chance of being busted running
shortwave too.

So come-on folks...... Shortwave is fun too.
All the very best
Sam The Dog.....

TOR-Radio on FM / Mediumwave and Shortwave
And many moons ago.. WNKR on FM and Shortwave.
info@torradio org / qq22.net / TorRadio.ORG

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Re: Shortwaves are fun too !

Post by SundayGroover » Wed Apr 03, 2019 9:05 pm

Not played around with SW apart from the 11m band on CB of course! (Still do).

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Re: Shortwaves are fun too !

Post by Albert H » Thu Apr 04, 2019 1:42 am

You're right, Sam.

Back in the early 80s, I tried a short wave set-up (on 6235kHz) which was run from a field site with an inverted V aerial over a tall tree. The earth was provided by connection to water and sewage pipes that ran beneath the corner of the field, by a road. The transmitter was built into an old milk crate, and had three car batteries to power it. Programmes came from cassette tape, using an "auto-reverse" car cassette deck - later as many as four car cassette decks were cascaded to give as much as 8 hours of continuous programme! The gear was concealed in a pit beneath a dustbin lid covered in earth, making it quite difficult to find.

We operated during daylight every Sunday, but got no response (by mail in those days) for four weeks at our mailing address. We were going to give up, until the guy who lived at the mailing address phoned me and asked when I could come 'round and collect our post. There were three mail bags full of letters and cards from about 40 countries - a stamp collector's dream!

That little station ran just 60 Watts peak (about 12½ Watts of carrier) and had a less than perfect aerial or earth, but was great fun. It's still on the air occasionally from the border between the Netherlands and Belgium, and is using only the third transmitter I built for it - one was destroyed by a lightning strike, and one was confiscated by the authorities.

The latest rig runs around 200W carrier and almost 1kW peak, using just eight cheap switching FETs in the final, and a PWM modulator. It's frequency agile - in 1kHz steps - and has a built-in three band compressor / limiter and adjustable audio bandwidth for the best use of the available channel space. The whole rig cost about €75 to build. The wire for the aerial and earth radials costs more!
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Re: Shortwaves are fun too !

Post by Clutter Free » Wed Apr 24, 2019 12:06 am

Hello...

Great to see some chat about Shortwave at last. :)

I have been operating AM since 2017, alternating between medium wave and Shortwave as I cant operate them both together just yet due to limited antenna space at my QTH.

Right now my 40 watt carrier shortwave rig is and has been on air non-stop over a week now and the 48-meter band is very much alive and kicking with many free radio stations. :tup

It is a great feeling to read the many radio blogs out there and find that those 40 watts have been logged in many places, including Massachusetts! All part of the fun of shortwave, or AM in general as the rigs are fun and (once you get the hang of it) simple to build, using cheap fets for the O/P, series modulate it and away you go.

A lot of the inspiration, schematics etc for AM rig building was, of course, trawled from many sources on the internet and from various posts/schematics on here by your good self Albert H, Cheers for those.

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Re: Shortwaves are fun too !

Post by SamTheDog » Wed May 01, 2019 1:00 pm

SUPERB ! Great to hear that there are some prople on here on the bands.... I've just finished building a 5 band valve based HF set.. I have a few I use on various bands.... Great Post Albert H. I never thought of using car tape-players for the audio-source, But I guess it makes sense if you're running on car-batteries. In the early days of WNKR the transmitter was powered from 12V car batteries, and the battery needed to be changed half-way through the show. meaning that one of us had to walk over to the TX-site and swap it out... The audio back then came from a short-range VHF link at about 180 MHz so no tapes. I once did an outside broadcast from a local pub carpark linking back to Barney in the studio and on to the 48M rig hidden amongst the local trees!

Later the more usual mains-powered transmitters used a twin-deck auto-reverse deck to give 4-hours run-time. We would get our shows to Barney who re-recorded them onto C120 tapes with the leaders cut-out and timed by stop-watch to exactly an hour. It was pretty accurate and ther DJs couls almost give out time-checks!... I still to this day can't work out how he has the patience to listen through my shows of rock/blues and weird-stuff...

Using FET based transmitters like yours Albert H is definately the way to go for anything serious! Running with valves is fun but lugging big heavy low powered rigs about in the countryside isn't my idea of a good day out!. I also build low power fet kit but far lower power than yours... I get about 40w carrier on 48 Metres. Getting a 200w / 1kW fet rig together is superb. Nice one !

I guess that you are in the USA Clutter Free ?.. do the authorities leave you alone there? I tend to run TOR for short periods on mediumwave and longer on the SW bands. and only occasionally on VHF-FM. it's just too hot in my part of the word to run for more than a few days at a time especially on VHF. although SW is much better... Having space at home for many aerials, especially on the longer wavelength SW bands and Mediunwave can be a problem. I have managed to squeeze three in, and they are all a compromise, and all need an ATU. For proper broadcasts, trees and buildings are the prefered-option with a link back to a studio or vehicle...

What do you guys ose for your mailing address? Back in the 80's and early 90's wuppertaal was used. But I just use email now. It would be fun to use paper QSL again! The programmes / music played here at TOR is rather anti government and that could lead to a little more interest than usual from the authorities here.... so PO-Boxes are a fair proposition still.

....... I feel inspired to build a higher power FET transmitter now.......
All the best
Sam The Dog.....

TOR-Radio on FM / Mediumwave and Shortwave
And many moons ago.. WNKR on FM and Shortwave.
info@torradio org / qq22.net / TorRadio.ORG

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Re: Shortwaves are fun too !

Post by SamTheDog » Thu May 02, 2019 6:52 am

.........ALSO...........
Over the past six months I have been using commercial marine HF-SSB sets to try some ssb broadcasts. I have a 120 w Australian set here that runs from 12V batteries so great to use from local woodland. And a rather bulky Skanti 250W set. But that needs a mains supply or a large set of batteries!

It would be interesting to see if many others in Europe were broadcasting SSB.
Sam The Dog.....

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And many moons ago.. WNKR on FM and Shortwave.
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Re: Shortwaves are fun too !

Post by SamTheDog » Thu May 02, 2019 7:00 am

SundayGroover wrote:
Wed Apr 03, 2019 9:05 pm
Not played around with SW apart from the 11m band on CB of course! (Still do).
Me Too SundayGroover... I have a 26FB... call and get on 27.555 when the skip is up..
and we have 11m sets in the cars here and at home.. Last year heard a chap with a very
glaswegian accent on CH19. I was trying to chat locally from home to a mobile at the time
and ended up talking to a chap in Scotland for a few minutes until he faded-out! so there is
a good deal of fun still on the 11m band... even on unexpected channels!
Sam The Dog.....

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And many moons ago.. WNKR on FM and Shortwave.
info@torradio org / qq22.net / TorRadio.ORG

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Re: Shortwaves are fun too !

Post by SundayGroover » Thu May 02, 2019 7:05 pm

SamTheDog wrote:
Thu May 02, 2019 7:00 am
SundayGroover wrote:
Wed Apr 03, 2019 9:05 pm
Not played around with SW apart from the 11m band on CB of course! (Still do).
Me Too SundayGroover... I have a 26FB... call and get on 27.555 when the skip is up..
and we have 11m sets in the cars here and at home.. Last year heard a chap with a very
glaswegian accent on CH19. I was trying to chat locally from home to a mobile at the time
and ended up talking to a chap in Scotland for a few minutes until he faded-out! so there is
a good deal of fun still on the 11m band... even on unexpected channels!
Yep sporadic E DX stuff coming in now and skip rising in the coming years working SSB on 555 along with decent UK contacts, plus US stuff on MID band using AM. A few locals on around here on UK 27/81 and we have a good chat but pretty quiet generally.
I've worked Barbados, Estonia, and all over Europe in past years and hope to het some good contacts again.
Sometimes the most fun is working DX on the standard 4 watts (or less!) - if conditions are right the extra power makes no difference!

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Re: Shortwaves are fun too !

Post by SamTheDog » Fri May 03, 2019 12:20 pm

Your right about power levels.... There's a lot to be said for not overcooking it.. A well set up SSB rig with a good mic can punch through more than a stronger signal through a linear.

Mobile I tend to run 6w AM/FM and 15w SSB but have a linear should I need it, to give me 80w am/fm and almost twice that on SSB. It spends most of it's time OFF.! My Mobile is a vintage 7-band ss3900 I bought in Spain for 50 euros.
That odd contact on UK-19 FMl ast year from Kent to Glasgow was on about 35W into a firestick from a crt ss9900.

Over the years I have found that a good signal and a decent antenna are the most important.. working 555 mobile usually happens at the 100+watt levels. But I agree it's fab fun to get a low-power long distance contact.
Sam The Dog.....

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And many moons ago.. WNKR on FM and Shortwave.
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Re: Shortwaves are fun too !

Post by SundayGroover » Fri May 03, 2019 7:16 pm

SamTheDog wrote:
Fri May 03, 2019 12:20 pm
Your right about power levels.... There's a lot to be said for not overcooking it.. A well set up SSB rig with a good mic can punch through more than a stronger signal through a linear.

Mobile I tend to run 6w AM/FM and 15w SSB but have a linear should I need it, to give me 80w am/fm and almost twice that on SSB. It spends most of it's time OFF.! My Mobile is a vintage 7-band ss3900 I bought in Spain for 50 euros.
That odd contact on UK-19 FMl ast year from Kent to Glasgow was on about 35W into a firestick from a crt ss9900.

Over the years I have found that a good signal and a decent antenna are the most important.. working 555 mobile usually happens at the 100+watt levels. But I agree it's fab fun to get a low-power long distance contact.
Good radio at an amazing price there!
For SSB (and other stuff of course) I use either a Colt 485 DX Black Shadow, an Elbex Pacific or a Ham International Concorde.
I have a Colt Excalibur which needs work and has defeated me at the moment :-(
When needed I have both mains (valve) amplfication or solid state available.
For local chit chat I generally just use the Uniace 200 or York 863. Although I have quite a few more tucked away!

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Re: Shortwaves are fun too !

Post by Albert H » Fri May 03, 2019 11:22 pm

I always found that 11m was too subject to the vagaries of the sunspot cycle and even the weather.

I've had an amateur licence since I was 14, and my favourite band was usually 14MHz. I made all my own gear, and enjoyed a lot of Trans-oceanic DX with just 5 Watts SSB. The Yanks running their kilowatts into beam aerials couldn't believe that the signal they were getting from Europe was such low power! I had a couple of wire dipoles (N-S & E-W) fed with ladder-line, and had a broadband balun at the bottom of the ladder-line.

Part of the secret to getting heard was good audio processing. I used two-band compression and limiting with very tight audio filtering. The other elements to a good signal were the antenna and a good earth, and making certain that I had no frequency drift whatsoever. Stability was achieved with a "huff & puff" stabiliser based on a frequency counter. I could tune along the band in 5 Hz steps with Crystal accuracy.

Since I left the UK, I've been too busy with real radio to deal with the hobby stuff!
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Re: Shortwaves are fun too !

Post by SamTheDog » Tue May 07, 2019 6:10 am

SundayGroover wrote:
Fri May 03, 2019 7:16 pm

Good radio at an amazing price there!
For SSB (and other stuff of course) I use either a Colt 485 DX Black Shadow, an Elbex Pacific or a Ham International Concorde.
I have a Colt Excalibur which needs work and has defeated me at the moment :-(
When needed I have both mains (valve) amplfication or solid state available.
For local chit chat I generally just use the Uniace 200 or York 863. Although I have quite a few more tucked away!
pll02a rigs like your Colt 485 used to be modified for extra bands etc.. But the standard rig is a great ssb set. Some people add the A-Channels on one of the switches to fill-in the gaps. The colt excalibur is a nice rig too, Isn't it pretty much the same as a hy-gain 5 I dont know the uniace or york rigs.. I've never had one... Back in the old-days Barney (old WNKR buddy) used to do all our cb mods and tune-ups... Now I tend to do my own although I'd rather be working on customers SSB-Marine and Buisness-radio kit when I'm not building HF kit for fun!

The superstar 3900 from Spain arrived here a a 40 channel FM/SSB set and I bought a new front for it, and the correct switches and other parts and turned it into an export-spec radio with 7-bands, A-Channels, Modded clarifieretc...
UK-FM (27/81) isn't fitted yet so I use the high/High-High bands with the coarse clarifier at around 9-O'clock to put the Tx/Rx on the UK channels I may program an eprom one day and do a proper UK-Conversion, but the radio spends most of the time on 555 or on chan 33 high FM (UK 19).
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And many moons ago.. WNKR on FM and Shortwave.
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Re: Shortwaves are fun too !

Post by SamTheDog » Tue May 07, 2019 6:32 am

Albert H wrote:
Fri May 03, 2019 11:22 pm
I always found that 11m was too subject to the vagaries of the sunspot cycle and even the weather.

I've had an amateur licence since I was 14, and my favourite band was usually 14MHz. I made all my own gear, and enjoyed a lot of Trans-oceanic DX with just 5 Watts SSB. The Yanks running their kilowatts into beam aerials couldn't believe that the signal they were getting from Europe was such low power! I had a couple of wire dipoles (N-S & E-W) fed with ladder-line, and had a broadband balun at the bottom of the ladder-line.

Part of the secret to getting heard was good audio processing. I used two-band compression and limiting with very tight audio filtering. The other elements to a good signal were the antenna and a good earth, and making certain that I had no frequency drift whatsoever. Stability was achieved with a "huff & puff" stabiliser based on a frequency counter. I could tune along the band in 5 Hz steps with Crystal accuracy.

Since I left the UK, I've been too busy with real radio to deal with the hobby stuff!
I've often been asked why I don't just become a licenced radio amateur and use the bands legally. and at some point I may well do that, It would certainly open-up a world of possible new people to contact. But I find there is something very quirky about just popping-up on a shortwave channel, saying my piece and dis-appearing into the haze again... for instance I had a transmitter up on 3945 for 60 hours over the weekend and yes, it was probably only heard by a couple of dozen people. but there's somthing cool about transmitters amongst the trees weeds and squirrels....

I still can't help to be impressed by the distance per watt levels attained by ham-radio operators. I have 10-10.6GHz microwave gear in amongst my linking kit. I generally use it for hops of a few miles at most. but when I was reading-up on the subject some operators have managed hundreds of miles. And yes. HF bands like 20M get some seriously impressive long ranges on low powers. I've not heard of huff & puff stabilisers before... I feel a google moment arriving...
Sam The Dog.....

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And many moons ago.. WNKR on FM and Shortwave.
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Re: Shortwaves are fun too !

Post by Albert H » Sat May 11, 2019 3:31 am

Sam - the simplest "Huff & Puff" can be built if you have a frequency display on your rig - you just look at the last digit, and if it's rising, you provide the opposite correction to the VCO.... It's a bit like a PLL, but it's possible to "spin the dial" and move frequency. When you settle on where you want it to be, the stabiliser holds it there.

Take a look at http://hanssummers.com/huffpuff/minimalist.html I've used a variant of the "fast" two-IC version for years for my occasional visits to 14MHz. My stabiliser is set up to tune in 50 Hz steps (great for CW), and will hold both the transmitter and the receiver on frequency for hours.

I also experimented recently with minimalist transmitter designs for clandestine use, and have come up with probably the cheapest and simplest AM shortwave rig that's possible. There are NO ferrite cores in the coils - the output end of the PA has big diameter coils wound around cardboard tubes. The output FETs cost 90p each, and the modulator is similarly cheap. The whole thing is designed to be throwaway.
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Re: Shortwaves are fun too !

Post by SamTheDog » Tue Jun 18, 2019 9:09 am

Albert H wrote:
Sat May 11, 2019 3:31 am
I also experimented recently with minimalist transmitter designs for clandestine use, and have come up with probably the cheapest and simplest AM shortwave rig that's possible. There are NO ferrite cores in the coils - the output end of the PA has big diameter coils wound around cardboard tubes. The output FETs cost 90p each, and the modulator is similarly cheap. The whole thing is designed to be throwaway.
Sounds interesting. I bet the core-less Ls are a fair size! My baby fet Tx is on a 4x6 (100 x 160) eurocard, made in my kitchen sink.
the only way I could get it all on the board was to use the usual t50 ferrites etc... I had a good number of IRF5xx fets from some scrap PSUs so they ended up getting used in the transmitters... Are you modulating the gate with a capacitor coupled low-power audio amp? or modulating the driver? (I'm modulating the driver transistor).
Sam The Dog.....

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And many moons ago.. WNKR on FM and Shortwave.
info@torradio org / qq22.net / TorRadio.ORG

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Re: Shortwaves are fun too !

Post by Albert H » Fri Jun 21, 2019 12:29 am

Recently, I've been modulating the final FET gates. This gives grossly distorted mod, but then I use lashings of envelope feedback to get rid of the distortion!

The envelope feedback method was a trick I saw in some commercial AM rigs in the 'States many years ago. My modulator is a simple op-amp which is part of the gate biasing circuit. You're just wanging the gain of the FETs around so that the amplitude of the output goes up and down. Unfortunately, the transfer characteristic of the FETs is not linear at all, leading to really bad distortion. I take a sniff of the output signal through a crude diode demodulator, scale it with an op-amp and put the inverted resultant audio back into the inverting input of the modulator op-amp as distortion correction. You slowly turn the gain of the feedback op-amp up until the distortion just disappears.....

I've also been playing with "out-phasing" rigs - a bit like a semiconductor version of "Ampliphase". The carrier comes from a DDS chip (programmed with a cheap PIC), and is split into two paths. The audio and inverted audio is fed to a couple of fast comparators, which (essentially) convert the carrier into PWM signals. These are then passed to an identical pair of Class D amplifiers, then to the output bridge circuit where the magic phase addition and cancellation happens. This is an incredibly efficient way of generating AM. There's a little AM station near me that has a rig using this principle. They get 80 Watts carrier for 88 Watts DC input (so the blank carrier efficiency is great) and fully modulated (a whole 1.55 Volts peak-to-peak of 1 kHz tone!) gives 360 Watts with 390 Watts consumption.

My third approach is "real" Ampliphase. I'm generating the carrier at 8 times the output frequency, then using a digital divider to get two carriers 135° apart. These are used as references for CMOS PLLs. The oscillators in the 4046 PLL ICs are then frequency modulated in opposite directions by the applied audio. The two squarewave carriers are therefore frequency modulated with respect to each other. Two identical FET amplifiers and a combining output bridge, and we have AM! I've got this working quite well on the bench (it'll still need a bit of envelope feedback), but I'm concerned about the effect that antenna matching (or mismatching) could have on the resultant AM.....

So much research to do..... so little time to do it in!
"Why is my rig humming?"
"Because it doesn't know the words!"
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