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29th Nov 2007, 11:46 pm | #1 |
Pentode
Join Date: Jul 2007
Location: Clophill, Bedfordshire, UK.
Posts: 127
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SSTRAN low power AM transmitter
I received my SSTRAN AMT3000 low power radio transmitter kit yesterday and tonight I have powered it up. It works well, as expected, but I would be interested in the experience of others with setting it up. In particular what sort of voltage readings do you get between T1 and T2 when setting C5? I get about 7 volts when I adjusted for peak value.
The range I get with the aerial just draped across the table does not get clear reception more than 30 or 40 feet away using a modern synthesised receiver and a little less with an older set (e.g. Bush MB60). I am sure that when I set it up carefully and set the modulation depth with a scope, I will get a very acceptable performance, but I would be interested in what others get. John |
30th Nov 2007, 11:51 pm | #2 |
Octode
Join Date: Jul 2006
Location: Willand, Devon, UK.
Posts: 1,023
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Re: SSTRAN low power AM transmitter
Mine covered the whole housing estate when first set up, I had to shorten the aerial wire quite a lot to reduce the range to just the house + garden. I don't think a set voltage is expected between T1 + T2, you just have to adjust it until you get the highest voltage at that particular frequency setting. Also try a different frequency if you haven't already. The aerial will also work a lot better vertical, and connecting the ground wire to earth will greatly improve performance.
Matty |
1st Dec 2007, 2:53 pm | #3 |
Octode
Join Date: Jun 2004
Location: Reading/Fakenham, UK.
Posts: 1,324
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Re: SSTRAN low power AM transmitter
A recent story from Radio World Newspaper about this transmitter:
"Mann’s Antique Radio Collector Fined for Uncertified AM Transmitters" www.rwonline.com/pages/s.0102/t.9952.html |
1st Dec 2007, 3:07 pm | #4 |
Moderator
Join Date: Jan 2003
Location: Ipswich, Suffolk, IP4, UK.
Posts: 21,289
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Re: SSTRAN low power AM transmitter
Don't get too concerned about it. It happened in the USA, not the UK. It also related to assembled transmitters, not kits. As far as I know the import of low power AM transmitter kits into the UK is not illegal.
So long as as you restrict coverage by using the shortest aerial possible no one is likely to complain about interference and no one will investigate.
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1st Dec 2007, 5:42 pm | #5 |
Dekatron
Join Date: Aug 2007
Location: W.Butterwick, near Doncaster UK.
Posts: 8,935
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Re: SSTRAN low power AM transmitter
Just a thought anyone tried modulating a signal generator and using that with a small aerial?
David |
1st Dec 2007, 6:14 pm | #6 | |
Nonode
Join Date: Jun 2005
Location: Western Lake District, Cumbria (CA20) - UK
Posts: 2,136
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Re: SSTRAN low power AM transmitter
Quote:
Works with my Philips PM5324 in the workshop. I haven't yet tried to see if I can get wider coverage than that. The PM5324 has a maximum 50mV available. Regards,
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Brian |
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1st Dec 2007, 7:10 pm | #7 | |
Administrator
Join Date: Dec 2002
Location: Cardiff
Posts: 9,072
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Re: SSTRAN low power AM transmitter
Quote:
The other possible problem is that you may not get it exactly on a 9kHz spacing channel unless it is accurately calibrated and the dial is fine enough to set it correctly. Not a big deal if the band is fairly clear though, but if there are adjacent stations you could have problems with whistles and breakthrough. If you have a sig gen then try it and see how you get on! |
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1st Dec 2007, 8:28 pm | #8 |
Dekatron
Join Date: Feb 2005
Location: St.Ippolyts, Hitchin, Hertfordshire QRA IO91UW
Posts: 3,518
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Re: SSTRAN low power AM transmitter
Not any more - we use a pantry transmitter - design published a couple of years back
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1st Dec 2007, 10:29 pm | #9 | |
Nonode
Join Date: Jun 2005
Location: Western Lake District, Cumbria (CA20) - UK
Posts: 2,136
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Re: SSTRAN low power AM transmitter
Quote:
I don't use an aerial with it as a rule, a test probe sticking out of the output socket give good coverage of the workbench and the test shelf (on FM as well as AM). AS Paul suggests, do try to keep clear of adjacent stations. Regards,
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Brian |
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2nd Dec 2007, 1:40 am | #10 |
Pentode
Join Date: Jul 2007
Location: Clophill, Bedfordshire, UK.
Posts: 127
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Re: SSTRAN low power AM transmitter
I don't believe my SSTRAN transmissions 'escape' outside my house and garden but when I have it in a permanent position I will do some tests to check.
John |
2nd Dec 2007, 9:31 am | #11 |
Dekatron
Join Date: Nov 2003
Location: Near Leeds, West Yorkshire, UK
Posts: 4,609
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Re: SSTRAN low power AM transmitter
Mine has about a yard of wire for an aerial, and radiates at least as far as, say, 25 yards to the garden or garage. Not tested it any further than that.
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Mike. |
2nd Dec 2007, 2:19 pm | #12 |
Triode
Join Date: Oct 2005
Location: Oakham, Rutland, UK.
Posts: 40
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Re: SSTRAN low power AM transmitter
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2nd Dec 2007, 3:09 pm | #13 |
Retired Dormant Member
Join Date: Jan 2007
Location: Westbury, Wiltshire, UK.
Posts: 2,451
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Re: SSTRAN low power AM transmitter
What does the 'compression' control do on the 3000? I can take a technical answer.
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2nd Dec 2007, 6:13 pm | #14 |
Pentode
Join Date: Jan 2007
Location: Stockport, Greater Manchester, UK.
Posts: 229
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Re: SSTRAN low power AM transmitter
Hi there,
Compression is reduction of the dynamic range of the input signal. Commercial stations often use a lot of compression to make the sound consistently loud and 'punchy'. Play with the level and make comparisons with other broadcast stations, you'll soon know when it sounds most acceptable. Regards Stu |
2nd Dec 2007, 10:06 pm | #15 |
Administrator
Join Date: Dec 2002
Location: Cardiff
Posts: 9,072
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Re: SSTRAN low power AM transmitter
Compression makes the quiet stuff louder and the louder stuff quieter, so that the level is more consistent regardless of program type. Back when stations broadcast the same thing on FM and AM you could hear the effect of the compression clearly by stitching between them. On AM more compression is used to keep the level up so that it masks the noise and interference from other stations.
With the SSTRAN, adjust until it sounds right to you with the music you listen to on the radios you're using. I reviewed the unit here http://www.vintage-radio.com/reviews/amt3000.html, At the current dollar rate it's even better value (probably around £45 plus whatever import duties you get charged). For this sort of money it's probably not worth designing your own, unless you want to do so for the challenge. |
2nd Dec 2007, 10:09 pm | #16 |
Administrator
Join Date: Dec 2002
Location: Cardiff
Posts: 9,072
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Re: SSTRAN low power AM transmitter
It's Chas's name for the small low power valve transmitter he built. Why "pantry", I don't know.
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2nd Dec 2007, 11:41 pm | #17 |
Dekatron
Join Date: Sep 2003
Location: Bolton, Greater Manchester, UK.
Posts: 6,644
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Re: SSTRAN low power AM transmitter
It's because that is where it sits at home, broadcasting good music for his vintage sets. Until it goes out on the road and he has problems with it!
Cheers, Steve P.
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3rd Dec 2007, 12:46 am | #18 |
Triode
Join Date: Oct 2005
Location: Oakham, Rutland, UK.
Posts: 40
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Re: SSTRAN low power AM transmitter
Thanks for enlightening me guys.
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3rd Dec 2007, 11:16 am | #19 |
Dekatron
Join Date: Aug 2007
Location: W.Butterwick, near Doncaster UK.
Posts: 8,935
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Re: SSTRAN low power AM transmitter
Re pantry transmitter,its not i dont think very low power!
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