[AMRadio] Re: Artificial Aerial Licence
-- Message: 1 Date: Tue, 15 Apr 2008 11:45:36 -0500 From: D. Chester [EMAIL PROTECTED] Subject: [AMRadio] Re: Artificial Aerial Licence To: amradio@mailman.qth.net Message-ID: [EMAIL PROTECTED] Content-Type: text/plain; format=flowed; charset=iso-8859-1; reply-type=original I never could figure out why a licence was ever required to work a transmitter into a non-radiating load. Don k4kyv Hi Don and Co, Well, what you have to remember is that after the introduction of radio in the early part of the 20th Century Britain and the US went completely separate ways with control and legislation. In the US, cable and radio companies were private concerns, profit-making. In the UK, all communications by cable and post were under the control of the General Post Office (GPO). When radio came along, the GPO took over the administration of the new medium and issued licences to all services, including amateurs. The whole ethos was of control, and not profit, from the outset, so it's not suprising that the GPO required a licence to allow one to build and test a transmitter, even into a dummy load. Yes, there was a licence required for domestic radio reception; I can't remember when it was revoked but certainly you needed one when I was a kid and also, at one time, a separate one for a car radio! You must remember that there were no large-scale commercial broadcasting in the UK until about the 1970s; as a kid I listened to pop music on Radio Luxembourg on 208 metres, because the BBC stations didn't play pop in any quantity. The spur to change all this came about in the mid 60s, when a bunch of pirate stations sprang up from ships and abandoned anti-aircraft forts off the UK coasts. These stations were a huge success and forced the BBC into launching a modern mass-appeal radio service. There is still a requirement to have a licence for TVs here; if you buy a TV in the local mall, the law requires the seller to inform the authorities of your address. If no TV licence is known at that address under your name, then expect postal harrassment and a visit from the Detector Van! The licence is about $275/year and goes to finance the BBC, even if you only watch non-BBC stations you still must have a licence. Having said all that, from a ham's point of view the situation has got much easier in the 42 years I've been licenced. Things are lot more easy-going and sensible changes to regulations are generally made without too much fuss and hassle. The UK radio spectrum management in now done by an outfit called OFCOM, having passed from the GPO, through the Home Office and The Radiocommunications Agency in my time. Hope this isn't too boring!! Roger/G3VKM -- Message: 2 Date: Tue, 15 Apr 2008 12:59:03 -0400 From: Ed Sieb [EMAIL PROTECTED] Subject: RE: [AMRadio] Re: Artificial Aerial Licence To: Discussion of AM Radio in the Amateur Service amradio@mailman.qth.net Cc: Don Chester K4KYV [EMAIL PROTECTED] Message-ID: [EMAIL PROTECTED] Content-Type: text/plain; charset=iso-8859-1 It's the UK Don. _Everything_ is regulated there. Ed, VA3ES -- Don k4kyv wrote: I never could figure out why a licence was ever required to work a transmitter into a non-radiating load. -- No virus found in this outgoing message. Checked by AVG. Version: 7.5.523 / Virus Database: 269.23.0/1379 - Release Date: 15/04/2008 18:10 __ Our Main Website: http://www.amfone.net AMRadio mailing list Searchable Archives: http://www.mail-archive.com/amradio@mailman.qth.net/ List Rules (must read!): http://w5ami.net/amradiofaq.html List Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net To unsubscribe, send an email to [EMAIL PROTECTED] with the word unsubscribe in the message body.
Re: [AMRadio] Re: Artificial Aerial Licence
Roger Basford wrote: Well, what you have to remember is that after the introduction of radio in the early part of the 20th Century Britain and the US went completely separate ways with control and legislation. Roger, thanks for that not-boring history - I suspect like many I knew parts of it, but it's an interesting contrast. Having never been a part of the pirate radio movement at the time, I really enjoyed listening to the reunion broadcast online last year, where many of the jocks from Radio Caroline and other pirates were back on the air - but over Pirate BBC Essex from offshore near Harwich this time. Even though they didn't have actual AM transmitters on the ships, it was great fun to listen to, wonder if they'll be doing this again? I knew the pirate broadcasters got the BBC to start playing top 40 music, but didn't realize they actually helped to change the way radio services were licensed in the UK. I would also suspect the Detector Van would have more difficulty with the modern receiver technology - is there a problem with TV bootlegging today, or is paying the license fee just part of the culture? 73, Bob W9RAN __ Our Main Website: http://www.amfone.net AMRadio mailing list Searchable Archives: http://www.mail-archive.com/amradio@mailman.qth.net/ List Rules (must read!): http://w5ami.net/amradiofaq.html List Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net To unsubscribe, send an email to [EMAIL PROTECTED] with the word unsubscribe in the message body.
[AMRadio] Re: Artificial Aerial Licence
Good afternoon Roger and all Your brief comments about licencing and the BBC brought to mind the certification decals I've encountered on three of my early English Crystal Sets. Each of the sets have not only the BBC decals, but the serial numbers are stamped into the wooden cabinets. The sets were truly licensed and registered when purchased. One of the crystal sets had a nice surprise tucked neatly inside. It was a B.B.C.A.A. (British Broadcasting Corporation Assurance Association) Wireless Policy. An insurance policy that provided limited coverage for damages incurred by lightning where an outside Aerial was deployed. This particular policy was never completed by the owner and is intact. No mention of the premium amount was given but it was for a period of six months. Coverage was increased when a W.L.A. (Wavelength Lightning Arrestor) was installed at the same time as the aerial. The address for the BBCAA was 825/826 Salisbury House, London Wall, E.C. 2 A small, but fine book on early British Wireless design is The Cat's Whisker by Jonathan Hill. Some very nice photos and a nice anthology of wireless broadcasting in England. It even has the history of the BBC stations beginning with London (2LO) on 361 metres and continuing through THIRD PROGRAMME on 460 metres in 1946. Thanks, Roger, for sharing your comments..definitely not boring. Best 73 de W4MIL Chuck -Original Message- From: Roger Basford [EMAIL PROTECTED] To: amradio@mailman.qth.net Sent: Wed, 16 Apr 2008 4:37 am Subject: [AMRadio] Re: Artificial Aerial Licence -- Message: 1 Date: Tue, 15 Apr 2008 11:45:36 -0500 From: D. Chester [EMAIL PROTECTED] Subject: [AMRadio] Re: Artificial Aerial Licence To: amradio@mailman.qth.net Message-ID: [EMAIL PROTECTED] Content-Type: text/plain; format=flowed; charset=iso-8859-1; reply-type=original I never could figure out why a licence was ever required to work a transmitter into a non-radiating load. Don k4kyv Hi Don and Co, Well, what you have to remember is that after the introduction of radio in the early part of the 20th Century Britain and the US went completely separate ways with control and legislation. In the US, cable and radio companies were private concerns, profit-making. In the UK, all communications by cable and post were under the control of the General Post Office (GPO). When radio came along, the GPO took over the administration of the new medium and issued licences to all services, including amateurs. The whole ethos was of control, and not profit, from the outset, so it's not suprising that the GPO required a licence to allow one to build and test a transmitter, even into a dummy load. Yes, there was a licence required for domestic radio reception; I can't remember when it was revoked but certainly you needed one when I was a kid and also, at one time, a separate one for a car radio! You must remember that there were no large-scale commercial broadcasting in the UK until about the 1970s; as a kid I listened to pop music on Radio Luxembourg on 208 metres, because the BBC stations didn't play pop in any quantity. The spur to change all this came about in the mid 60s, when a bunch of pirate stations sprang up from ships and abandoned anti-aircraft forts off the UK coasts. These stations were a huge success and forced the BBC into launching a modern mass-appeal radio service. There is still a requirement to have a licence for TVs here; if you buy a TV in the local mall, the law requires the seller to inform the authorities of your address. If no TV licence is known at that address under your name, then expect postal harrassment and a visit from the Detector Van! The licence is about $275/year and goes to finance the BBC, even if you only watch non-BBC stations you still must have a licence. Having said all that, from a ham's point of view the situation has got much easier in the 42 years I've been licenced. Things are lot more easy-going and sensible changes to regulations are generally made without too much fuss and hassle. The UK radio spectrum management in now done by an outfit called OFCOM, having passed from the GPO, through the Home Office and The Radiocommunications Agency in my time. Hope this isn't too boring!! Roger/G3VKM -- Message: 2 Date: Tue, 15 Apr 2008 12:59:03 -0400 From: Ed Sieb [EMAIL PROTECTED] Subject: RE: [AMRadio] Re: Artificial Aerial Licence To: Discussion of AM Radio in the Amateur Service amradio@mailman.qth.net Cc: Don Chester K4KYV [EMAIL PROTECTED] Message-ID: [EMAIL PROTECTED] Content-Type: text/plain; charset=iso-8859-1 It's the UK Don. _Everything_ is regulated there.
[AMRadio] Re: capacitors for tank circuits
From: John Coleman [EMAIL PROTECTED] The size of the spilt stator capacitor that you are looking for (will) need to be determined by the voltage and current that you intend to run, The ratio of I:E determines the capacitance There are charts in the handbooks for this purpose. Be sure to consider that you are doing push pull with a balanced tank circuit as the required capacitance is only a quarter of that required for non-balanced. The voltage will determine the needed spacing of the plates. If you raise the tank capacitor above the chassis on insulators and connect the rotor to B+ you can get by with less spacing but you will need to use and insulated coupler to the knob shaft and be sure the knob shaft is grounded for safety. You can also accomplished the same thing by using two large RF chokes, one per tube, and capacitive coupling the RF to the tank circuit as is done in most PI net circuits. This way the plate tank cap can be mounted to chassis and the RF choke at the center of the tank coil can be grounded. The idea is to not have a DC + modulation voltage across the plates of the tank capacitor but just RF voltage. Capacitive coupling, as was just described, is a neat way to do this but it requires the very large long RF chokes and good coupling capacitors. For a balanced tank circuit, the capacitance is one fourth, but the voltage rating must be double that of single-ended. The reason for this is, that for a single-ended final, the tube is working into only half the balanced tank circuit, but the coil acts as a step-up autotransformer and the induced voltage across the other half of the coil is approximately equal to the voltage on the half that the tube works into, giving an rf voltage end-to-end that is twice that which is actually generated by the tube. It is exactly the same in the case of push-pull, since in class-C or even class-B service, only one tube is working into the tank circuit at a time, and each tube is working into one half of the tank circuit. Or you could think of it as each tube generating equal rf voltage, but the outputs of the two tubes are in series as they work into the tank circuit. But a capacitor with twice the voltage rating and one fourth the capacitance is equivalent to taking the original single-ended capacitor, splitting it in half, and wiring each of those halves in series. That is exactly what we mean by a split-stator capacitor. For example, take the BC-610, which runs the final at 2000 volts @ 250 mills. The tank capacitor is split stator with 150 pf per section. If the final were changed to unbalanced output, for example by substituting a 4-250 for the 250TH and converting to a pi-network, or by changing the grid tank to balanced and running the plate tank unbalanced, the final tank capacitor would need to be 300 pf in order to keep the tank circuit Q the same. That could easily be accomplished by wiring the two sections of the 150/150 split stator capacitor in parallel. The parallel connection gives 300 pf at approximately 7 kv rating. The series connection as used in the balanced tank, renders 75 pf at 14 kv rating. A single ended capacitor rated 75 pf @ 14 kv would be about the same size as the dual 150 @ 7 kv, and when new, the cost would have been about the same. The point is, for a given power level and plate voltage/plate current ratio, the physical size and cost of the tank capacitor is approximately the same, whether the tank is balanced or unbalanced. If a split stator capacitor is used, it can easily be connected up as a balanced or unbalanced tank. Of course, the number of turns in the balanced tank will be double that of the single ended one, since 4 times the inductance is required to maintain resonance at the same frequency.OTOH, the wire size in the unbalanced tank will need to be heavier, since the circulating rf current is higher with the higher L to C ratio. I always raise my entire pushpull tank above ground and put the full HV on the whole capacitor, and series feed through the tank coil. The rf choke has to do much less work than with parallel feed, because with series feed the rf choke connects to a zero rf voltage point on the tank coil, while with parallel feed, the choke goes to the plate of the tube and thus the full rf voltage appears across the choke. Theoretically, with series feed the B+ lead could be connected directly to the cold spot on the coil with no rf choke at all, but in a practical circuit, the B+ leads needs to be isolated from the tank coil with a choke since it is virtually impossible to maintain perfect balance in a nominally balanced tank circuit. Don k4kyv __ Our Main Website: http://www.amfone.net AMRadio mailing list Searchable Archives: http://www.mail-archive.com/amradio@mailman.qth.net/ List Rules (must read!): http://w5ami.net/amradiofaq.html List Home:
[AMRadio] Coil for PP grid circuit
Thanks to all for the information on the capacitor. Now I have another question. I know that the manufactured coils of ancient times were rated as to watts. I have a few old coils that I know the ratings of, or they are stamped on the coil. There are some that I don't know the ratings of, such as the JVL 80, which is rather large diameter, on a five pin base, and the JVC 80, which is smaller diameter, and also on a five pin base. This rig I'm gathering parts for could need 75, or more, watts drive. Would either of the above coils work in the grid circuit, given that much drive? The next size up, I think, is the JVB? How many watts will it handle? 73, Barrie, W7ALW __ Our Main Website: http://www.amfone.net AMRadio mailing list Searchable Archives: http://www.mail-archive.com/amradio@mailman.qth.net/ List Rules (must read!): http://w5ami.net/amradiofaq.html List Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net To unsubscribe, send an email to [EMAIL PROTECTED] with the word unsubscribe in the message body.
RE: [AMRadio] Re: capacitors for tank circuits
Yep, very good points Don. What I was mostly trying to say to Barrie was that tubes should be chosen first so as to acquire a ratio of plate current to plate voltage that will be used and then design the tank circuit around that. 400 Watts DC input can be achieved by 8 - 6146s in push pull parallel but because of the low voltage and high current the tank circuit would have a much larger amount of capacitance and less coil than a tank that is for a pair of 75ths at high voltage and less current. Also Barrie, when using the charts, you should be sure to choose the one for class C not the chart for linear operation. The tank Q is all together different. I used the example of the 8 - 6146s only as an example. If you were to try that you would have a difficult time finding a modulation XFMR to match the 900 ohm load that those tubes would represent to a modulator. John, WA5BXO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of D. Chester Sent: Wednesday, April 16, 2008 11:42 AM To: amradio@mailman.qth.net Subject: [AMRadio] Re: capacitors for tank circuits From: John Coleman [EMAIL PROTECTED] The size of the spilt stator capacitor that you are looking for (will) need to be determined by the voltage and current that you intend to run, The ratio of I:E determines the capacitance There are charts in the handbooks for this purpose. Be sure to consider that you are doing push pull with a balanced tank circuit as the required capacitance is only a quarter of that required for non-balanced. The voltage will determine the needed spacing of the plates. If you raise the tank capacitor above the chassis on insulators and connect the rotor to B+ you can get by with less spacing but you will need to use and insulated coupler to the knob shaft and be sure the knob shaft is grounded for safety. You can also accomplished the same thing by using two large RF chokes, one per tube, and capacitive coupling the RF to the tank circuit as is done in most PI net circuits. This way the plate tank cap can be mounted to chassis and the RF choke at the center of the tank coil can be grounded. The idea is to not have a DC + modulation voltage across the plates of the tank capacitor but just RF voltage. Capacitive coupling, as was just described, is a neat way to do this but it requires the very large long RF chokes and good coupling capacitors. For a balanced tank circuit, the capacitance is one fourth, but the voltage rating must be double that of single-ended. The reason for this is, that for a single-ended final, the tube is working into only half the balanced tank circuit, but the coil acts as a step-up autotransformer and the induced voltage across the other half of the coil is approximately equal to the voltage on the half that the tube works into, giving an rf voltage end-to-end that is twice that which is actually generated by the tube. It is exactly the same in the case of push-pull, since in class-C or even class-B service, only one tube is working into the tank circuit at a time, and each tube is working into one half of the tank circuit. Or you could think of it as each tube generating equal rf voltage, but the outputs of the two tubes are in series as they work into the tank circuit. But a capacitor with twice the voltage rating and one fourth the capacitance is equivalent to taking the original single-ended capacitor, splitting it in half, and wiring each of those halves in series. That is exactly what we mean by a split-stator capacitor. For example, take the BC-610, which runs the final at 2000 volts @ 250 mills. The tank capacitor is split stator with 150 pf per section. If the final were changed to unbalanced output, for example by substituting a 4-250 for the 250TH and converting to a pi-network, or by changing the grid tank to balanced and running the plate tank unbalanced, the final tank capacitor would need to be 300 pf in order to keep the tank circuit Q the same. That could easily be accomplished by wiring the two sections of the 150/150 split stator capacitor in parallel. The parallel connection gives 300 pf at approximately 7 kv rating. The series connection as used in the balanced tank, renders 75 pf at 14 kv rating. A single ended capacitor rated 75 pf @ 14 kv would be about the same size as the dual 150 @ 7 kv, and when new, the cost would have been about the same. The point is, for a given power level and plate voltage/plate current ratio, the physical size and cost of the tank capacitor is approximately the same, whether the tank is balanced or unbalanced. If a split stator capacitor is used, it can easily be connected up as a balanced or unbalanced tank. Of course, the number of turns in the balanced tank will be double that of the single ended one, since 4 times the inductance is required to maintain resonance at the same frequency.OTOH, the wire size in the unbalanced
RE: [AMRadio] Re: capacitors for tank circuits
Sorry if this is doubled - I think I sent it with the wrong SMTP the first time so here it goes again. Yep, very good points Don. What I was mostly trying to say to Barrie was that tubes should be chosen first so as to acquire a ratio of plate current to plate voltage that will be used and then design the tank circuit around that. 400 Watts DC input can be achieved by 8 - 6146s in push pull parallel but because of the low voltage and high current the tank circuit would have a much larger amount of capacitance and less coil than a tank that is for a pair of 75ths at high voltage and less current. Also Barrie, when using the charts, you should be sure to choose the one for class C not the chart for linear operation. The tank Q is all together different. I used the example of the 8 - 6146s only as an example. If you were to try that you would have a difficult time finding a modulation XFMR to match the 900 ohm load that those tubes would represent to a modulator. John, WA5BXO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of D. Chester Sent: Wednesday, April 16, 2008 11:42 AM To: amradio@mailman.qth.net Subject: [AMRadio] Re: capacitors for tank circuits From: John Coleman [EMAIL PROTECTED] The size of the spilt stator capacitor that you are looking for (will) need to be determined by the voltage and current that you intend to run, The ratio of I:E determines the capacitance There are charts in the handbooks for this purpose. Be sure to consider that you are doing push pull with a balanced tank circuit as the required capacitance is only a quarter of that required for non-balanced. The voltage will determine the needed spacing of the plates. If you raise the tank capacitor above the chassis on insulators and connect the rotor to B+ you can get by with less spacing but you will need to use and insulated coupler to the knob shaft and be sure the knob shaft is grounded for safety. You can also accomplished the same thing by using two large RF chokes, one per tube, and capacitive coupling the RF to the tank circuit as is done in most PI net circuits. This way the plate tank cap can be mounted to chassis and the RF choke at the center of the tank coil can be grounded. The idea is to not have a DC + modulation voltage across the plates of the tank capacitor but just RF voltage. Capacitive coupling, as was just described, is a neat way to do this but it requires the very large long RF chokes and good coupling capacitors. For a balanced tank circuit, the capacitance is one fourth, but the voltage rating must be double that of single-ended. The reason for this is, that for a single-ended final, the tube is working into only half the balanced tank circuit, but the coil acts as a step-up autotransformer and the induced voltage across the other half of the coil is approximately equal to the voltage on the half that the tube works into, giving an rf voltage end-to-end that is twice that which is actually generated by the tube. It is exactly the same in the case of push-pull, since in class-C or even class-B service, only one tube is working into the tank circuit at a time, and each tube is working into one half of the tank circuit. Or you could think of it as each tube generating equal rf voltage, but the outputs of the two tubes are in series as they work into the tank circuit. But a capacitor with twice the voltage rating and one fourth the capacitance is equivalent to taking the original single-ended capacitor, splitting it in half, and wiring each of those halves in series. That is exactly what we mean by a split-stator capacitor. For example, take the BC-610, which runs the final at 2000 volts @ 250 mills. The tank capacitor is split stator with 150 pf per section. If the final were changed to unbalanced output, for example by substituting a 4-250 for the 250TH and converting to a pi-network, or by changing the grid tank to balanced and running the plate tank unbalanced, the final tank capacitor would need to be 300 pf in order to keep the tank circuit Q the same. That could easily be accomplished by wiring the two sections of the 150/150 split stator capacitor in parallel. The parallel connection gives 300 pf at approximately 7 kv rating. The series connection as used in the balanced tank, renders 75 pf at 14 kv rating. A single ended capacitor rated 75 pf @ 14 kv would be about the same size as the dual 150 @ 7 kv, and when new, the cost would have been about the same. The point is, for a given power level and plate voltage/plate current ratio, the physical size and cost of the tank capacitor is approximately the same, whether the tank is balanced or unbalanced. If a split stator capacitor is used, it can easily be connected up as a balanced or unbalanced tank. Of course, the number of turns in the balanced tank will be double that of the single ended one, since 4 times the inductance
