SSTRAN low power AM transmitter - UK Vintage Radio Repair and Restoration Discussion Forum

Mullard · 29th Nov 2007, 11:46 pm

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

matthewhouse · 30th Nov 2007, 11:51 pm

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

Ian - G4JQT · 1st Dec 2007, 2:53 pm

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

Station X · 1st Dec 2007, 3:07 pm

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.

HamishBoxer · 1st Dec 2007, 5:42 pm

Just a thought anyone tried modulating a signal generator and using that with a small aerial?

David

Brian R Pateman · 1st Dec 2007, 6:14 pm

Quote:

Originally Posted by HamishBoxer

Just a thought anyone tried modulating a signal generator and using that with a small aerial?

David

Yes,

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,

Paul Stenning · 1st Dec 2007, 7:10 pm

Quote:

Originally Posted by HamishBoxer

Just a thought anyone tried modulating a signal generator and using that with a small aerial?

David

That's how they do it at Radiophile restoration and build contests (or certainly did a few years ago), using an Advance sig gen on maximum output. The range is not great, certainly less than an SSTRAN, but it works well enough within the same smallish room where sets are judged.

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!

Sean Williams · 1st Dec 2007, 8:28 pm

Not any more - we use a pantry transmitter - design published a couple of years back

Brian R Pateman · 1st Dec 2007, 10:29 pm

Quote:

Originally Posted by Paul Stenning

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!

In my case the Philips is my transfer standard so I keep it pretty much spot on for calibration.

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,

Mullard · 2nd Dec 2007, 1:40 am

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

Mike Phelan · 2nd Dec 2007, 9:31 am

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.

Dynamo · 2nd Dec 2007, 2:19 pm

Quote:

Originally Posted by Sean Williams

Not any more - we use a pantry transmitter - design published a couple of years back

Ok, I guess that I'm showing my ignorance here because nobody else has asked, but what is a pantry transmitter?

Boom · 2nd Dec 2007, 3:09 pm

What does the 'compression' control do on the 3000? I can take a technical answer.

stuie319 · 2nd Dec 2007, 6:13 pm

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

Paul Stenning · 2nd Dec 2007, 10:06 pm

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.

Paul Stenning · 2nd Dec 2007, 10:09 pm

Quote:

Originally Posted by Dynamo

Ok, I guess that I'm showing my ignorance here because nobody else has asked, but what is a pantry transmitter?

It's Chas's name for the small low power valve transmitter he built. Why "pantry", I don't know.

Steve_P · 2nd Dec 2007, 11:41 pm

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.

Dynamo · 3rd Dec 2007, 12:46 am

Thanks for enlightening me guys.

HamishBoxer · 3rd Dec 2007, 11:16 am

Re pantry transmitter,its not i dont think very low power!

29th Nov 2007, 11:46 pm	#1
Mullard Pentode Join Date: Jul 2007 Location: Clophill, Bedfordshire, UK. Posts: 127	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
matthewhouse Octode Join Date: Jul 2006 Location: Willand, Devon, UK. Posts: 1,023	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
Ian - G4JQT Octode Join Date: Jun 2004 Location: Reading/Fakenham, UK. Posts: 1,324	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
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,289	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. __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

1st Dec 2007, 5:42 pm	#5
HamishBoxer Dekatron Join Date: Aug 2007 Location: W.Butterwick, near Doncaster UK. Posts: 8,935	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, 8:28 pm	#8
Sean Williams Dekatron Join Date: Feb 2005 Location: St.Ippolyts, Hitchin, Hertfordshire QRA IO91UW Posts: 3,518	Re: SSTRAN low power AM transmitter Not any more - we use a pantry transmitter - design published a couple of years back __________________ Engineers make things work and have spare bits when finished

2nd Dec 2007, 1:40 am	#10
Mullard Pentode Join Date: Jul 2007 Location: Clophill, Bedfordshire, UK. Posts: 127	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
Mike Phelan Dekatron Join Date: Nov 2003 Location: Near Leeds, West Yorkshire, UK Posts: 4,609	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. __________________ Mike.

2nd Dec 2007, 3:09 pm	#13
Boom Retired Dormant Member Join Date: Jan 2007 Location: Westbury, Wiltshire, UK. Posts: 2,451	Re: SSTRAN low power AM transmitter What does the 'compression' control do on the 3000? I can take a technical answer.

2nd Dec 2007, 6:13 pm	#14
stuie319 Pentode Join Date: Jan 2007 Location: Stockport, Greater Manchester, UK. Posts: 229	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
Paul Stenning Administrator Join Date: Dec 2002 Location: Cardiff Posts: 9,072	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. __________________ Paul Stenning Forum Admin/Owner and BVWS Webmaster

2nd Dec 2007, 11:41 pm	#17
Steve_P Dekatron Join Date: Sep 2003 Location: Bolton, Greater Manchester, UK. Posts: 6,644	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. __________________ If we've always had it, why is the Car Boot open? You're not sneaking another Old TV in are you...?

3rd Dec 2007, 12:46 am	#18
Dynamo Triode Join Date: Oct 2005 Location: Oakham, Rutland, UK. Posts: 40	Re: SSTRAN low power AM transmitter Thanks for enlightening me guys.

3rd Dec 2007, 11:16 am	#19
HamishBoxer Dekatron Join Date: Aug 2007 Location: W.Butterwick, near Doncaster UK. Posts: 8,935	Re: SSTRAN low power AM transmitter Re pantry transmitter,its not i dont think very low power!