Re: [AMRadio] Ferroresonant transformer revisited
In a message dated 5/10/06 7:26:42 PM, [EMAIL PROTECTED] writes: I use a T-368 PTO as my main station vfo. I stabilised it by running the filaments off a regulated DC supply. Also use it to run mic preamp. Now have stable VFO and hum-free microphone preamp. I'm not sure why a small fraction of a percentage variation in filament voltage will cause such noticeable drift. Without the regulated filament voltage, neither the A4 nor the T-368 pto are stable enough to work 40m cw using a narrow filter. T-368's following the Basic model included a constant voltage xformer for the PTO filaments. Dennis D. W7QHO Glendale, CA
Re: [AMRadio] Ferroresonant transformer revisited
I would like to see pictures also. I have one 450TL and a filament transformer for it. Joe W4AAB - Original Message - From: Rick Brashear [EMAIL PROTECTED] To: Discussion of AM Radio amradio@mailman.qth.net Sent: Wednesday, May 10, 2006 8:16 PM Subject: Re: [AMRadio] Ferroresonant transformer revisited Geoff... If you get a chance would you send along a picture or two of the 450T amplifier? I looked at the tube ratings and I have the iron to get about 3/4 way to the top of the scale. Thanks, Rick/K5IZ __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb
Re: [AMRadio] Ferroresonant transformer revisited
crawfish wrote: I would like to see pictures also. I have one 450TL and a filament transformer for it. Joe W4AAB - Original Message - Geoff... If you get a chance would you send along a picture or two of the 450T amplifier? I looked at the tube ratings and I have the iron to get about 3/4 way to the top of the scale. Thanks, Rick/K5IZ Here y'all go... *http://tinyurl.com/pavrt -- 73 = Best Regards, -Geoff/W5OMR *
Re: [AMRadio] Ferroresonant transformer revisited
Donald Chester wrote: This sounds similar to my experiences with a Sola constant voltage transformer. Is that what a ferroresonant transformer is? Don k4kyv I believe they are one and the same, Don. Sola is a manufacturer of ferroresonant transformers. Rick/K5IZ John Coleman ARS WA5BXO wrote: They are also called CVT (for Constant Voltage Transformer) I think or is there a slight difference that I am not aware of?? John, WA5BXO The transformer I had (which ultimatly went back to Ronnie/W5SUM when he got my 450TL's) was labled a Sola Constant Voltage Transformer. 90 ~ 150v input, 7.5v ouput @ 42amps. I remember hooking the thing up one time, to check some tubes (450's) and with just the primary connected, the durn thing was 'noisey'. Made noise, just sitting there, with no load. Noise didn't change with a load, either, but that transformer sure did lite up a pair of 450TL's... 7.5v @ 12amps, each. -- 73 = Best Regards, -Geoff/W5OMR A: Yes. Q: Are you sure? A: Because it reverses the logical flow of conversation. Q: Why is top posting annoying in email?
RE: [AMRadio] Ferroresonant transformer revisited
Now that is interesting Geoff. I didn't realize that Solo made filament XFMRs. And because directly heated cathode type transmitting tubes are very sensitive to filament voltage then it makes since to have a transformer that will deliver the proper voltage regardless of input. John, WA5BXO
Re: [AMRadio] Ferroresonant transformer revisited
John E. Coleman (ARS WA5BXO) wrote: Now that is interesting Geoff. I didn't realize that Solo made filament XFMRs. And because directly heated cathode type transmitting tubes are very sensitive to filament voltage then it makes since to have a transformer that will deliver the proper voltage regardless of input. John, WA5BXO oh, yeah, you betcha! I've seen a few Sola filament transformers at different hamfests. heavy duty comes to mind, as the best way to describe 'em. -Geoff
RE: [AMRadio] Ferroresonant transformer revisited
I have the following Sola ferroresonant CV transformers for sale. The filament transformers are extremely useful for circuits sensitive to voltage variation. Sola NOS constant voltage transformer, 385V each side of CT at 110ma, plus 5V at 2A and 6.3VCT at 3 amps. Some scratches on nice gray case. Hookup diagram on case. $12 plus $8 US Priority flat rate box mailing. Sola NOS constant voltage transformer, 118V at 254ma and 330V at ??ma. With 3UF 330VAC capacitor for 330V hookup. Hookup diagram on case. $6 plus $8 US Priority flat rate box mailing. Sola Model 21248 NOS constant voltage filament transformers (2 to sell). These have a 5V winding and a 6.3V winding. Neither one is center tapped. Not sure of current rating but these things are big and heavy-about 1.5 times the size of the one above with the 2 filament windings-with no HV winding! So I'd say that these are about 5 amps at 5V and another 5 amps at 6.3V. $10 each. Brand new in nice gray cases. 73, Don Merz, N3RHT -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of W5OMR/Geoff Sent: Wednesday, May 10, 2006 9:49 AM To: Discussion of AM Radio Subject: Re: [AMRadio] Ferroresonant transformer revisited John E. Coleman (ARS WA5BXO) wrote: Now that is interesting Geoff. I didn't realize that Solo made filament XFMRs. And because directly heated cathode type transmitting tubes are very sensitive to filament voltage then it makes since to have a transformer that will deliver the proper voltage regardless of input. John, WA5BXO oh, yeah, you betcha! I've seen a few Sola filament transformers at different hamfests. heavy duty comes to mind, as the best way to describe 'em. -Geoff __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb The information contained in this e-mail may be confidential and is intended solely for the use of the named addressee. Access, copying or re-use of the e-mail or any information contained therein by any other person is not authorized. If you are not the intended recipient please notify us immediately by returning the e-mail to the originator.(17b)
Re: [AMRadio] Ferroresonant transformer revisited
No doubt, they are noisy rascals, hot too. Geoff, I'm glad you mentioned 450TL. I have one I acquired with an old BC-610 someone had hacked up trying to make an amplifier. Is there a way to test more than the filament other than putting it in a working amplifier? I'd kind of like to build something around it, but would hate to get it all complete only to find the tube was too weak or dead. Rick/K5IZ W5OMR/Geoff wrote: The transformer I had (which ultimatly went back to Ronnie/W5SUM when he got my 450TL's) was labled a Sola Constant Voltage Transformer. 90 ~ 150v input, 7.5v ouput @ 42amps. I remember hooking the thing up one time, to check some tubes (450's) and with just the primary connected, the durn thing was 'noisey'. Made noise, just sitting there, with no load. Noise didn't change with a load, either, but that transformer sure did lite up a pair of 450TL's... 7.5v @ 12amps, each. -- 73 = Best Regards, -Geoff/W5OMR A: Yes. Q: Are you sure? A: Because it reverses the logical flow of conversation. Q: Why is top posting annoying in email? __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb
Re: [AMRadio] Ferroresonant transformer revisited
Rick Brashear wrote: No doubt, they are noisy rascals, hot too. Geoff, I'm glad you mentioned 450TL. I have one I acquired with an old BC-610 someone had hacked up trying to make an amplifier. Is there a way to test more than the filament other than putting it in a working amplifier? I'd kind of like to build something around it, but would hate to get it all complete only to find the tube was too weak or dead. Rick/K5IZ Other than testing the filaments, no - I don't know of a way other than comparing it in an amp designed to use 'em. Speaking of which, Rick... I've got an amp that someone started to home-brew, designed around a 450T. Filament is 220v primary, at 7.5v big peice of copper tubing for a coil, tapped for 80, 40, 20 and 10m. And, I have a brighly glowing 450TL to go along with it. If you're interested, I'll send some pictures of it. -- 73 = Best Regards, -Geoff/W5OMR
Re: [AMRadio] Ferroresonant transformer revisited
I don't know if I can afford it, but I'd like to see some pictures. How far along is it and which parts are still needed? I'm assuming there is no HV supply, so what would it require about 2500 volts at half an amp? Rick/K5IZ W5OMR/Geoff wrote: Other than testing the filaments, no - I don't know of a way other than comparing it in an amp designed to use 'em. Speaking of which, Rick... I've got an amp that someone started to home-brew, designed around a 450T. Filament is 220v primary, at 7.5v big peice of copper tubing for a coil, tapped for 80, 40, 20 and 10m. And, I have a brighly glowing 450TL to go along with it. If you're interested, I'll send some pictures of it. -- 73 = Best Regards, -Geoff/W5OMR
Re: [AMRadio] Ferroresonant transformer revisited
W5OMR/Geoff wrote: Other than testing the filaments, no - I don't know of a way other than comparing it in an amp designed to use 'em. Speaking of which, Rick... I've got an amp that someone started to home-brew, designed around a 450T. Filament is 220v primary, at 7.5v big peice of copper tubing for a coil, tapped for 80, 40, 20 and 10m. And, I have a brighly glowing 450TL to go along with it. If you're interested, I'll send some pictures of it. I don't know if I can afford it, but I'd like to see some pictures. How far along is it and which parts are still needed? I'm assuming there is no HV supply, so what would it require about 2500 volts at half an amp? Except for the B+ supply, everything is there. The 450TH/L, according the spec sheet, will take up to 6kVDC on the plate. You'll likely need a bit more current... 450TH spec-sheet -- http://tinyurl.com/p5f85 -- 73 = Best Regards, -Geoff/W5OMR
Re: [AMRadio] Ferroresonant transformer revisited
I've got a nice plate transformer that will kick out 3800 volts, but I don't think the current rating is over half and amp. I'll look on the link you provided and se if it's feasible for me to even dream about this one. Rick/K5IZ W5OMR/Geoff wrote: Except for the B+ supply, everything is there. The 450TH/L, according the spec sheet, will take up to 6kVDC on the plate. You'll likely need a bit more current... 450TH spec-sheet -- http://tinyurl.com/p5f85 -- 73 = Best Regards, -Geoff/W5OMR
Re: [AMRadio] Ferroresonant transformer revisited
John E. Coleman (ARS WA5BXO) wrote: I'm sure you realize that a pair of those tubes is capable of up to 3600 watts plate input and 2700 watts output with a PEP of go knows where in class C. But with their 900 watts plate dissipation capability, they would make a cool linear. Just drive the grids with a 50 ohm load on it. If you do that instead of GG, I would still neutralize some how. John Wish I still had three of 'em, and that Sola CVT which was 7.5v @ 42 Amps. 3 of 'em, with 3kV DC on 'em, and raise the Q in the tank... a linear for -any- mode, at the 'legal limit'. problem with that is, winding a filament choke that big. -- 73 = Best Regards, -Geoff/W5OMR
RE: [AMRadio] Ferroresonant transformer revisited
The filament choke is why I said to just drive the grid direct or maybe put a 50 ohm load on the grid. John, WA5BXO
Re: [AMRadio] Ferroresonant transformer revisited
Yea right! You would still run 100 watts RF output to keep the neighbors happy! Hmmm, power input 150 watts + plus 315 watts filament for 100 watts output. Isn't that about 22% efficient? :-) Jim --- W5OMR/Geoff [EMAIL PROTECTED] wrote: John E. Coleman (ARS WA5BXO) wrote: I'm sure you realize that a pair of those tubes is capable of up to 3600 watts plate input and 2700 watts output with a PEP of go knows where in class C. But with their 900 watts plate dissipation capability, they would make a cool linear. Just drive the grids with a 50 ohm load on it. If you do that instead of GG, I would still neutralize some how. John Wish I still had three of 'em, and that Sola CVT which was 7.5v @ 42 Amps. 3 of 'em, with 3kV DC on 'em, and raise the Q in the tank... a linear for -any- mode, at the 'legal limit'. problem with that is, winding a filament choke that big. -- 73 = Best Regards, -Geoff/W5OMR __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb
RE: [AMRadio] Ferroresonant transformer revisited
Since peak to peak grid swing is a big item here, maybe have an imput 1:4 balun, and a 200 ohm resistor to ground instead of no balun and a 50 ohm resistor. That would double the P-P swing to the grid for a given amount of drive power. You could go for even higher ratios if drive power is limited. --- John E. Coleman (ARS WA5BXO) [EMAIL PROTECTED] wrote: The filament choke is why I said to just drive the grid direct or maybe put a 50 ohm load on the grid. John, WA5BXO __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb
Re: [AMRadio] Ferroresonant transformer revisited
John E. Coleman (ARS WA5BXO) wrote: BTW, ,John - those Transistors I got, and told you about (for the solid-state audio driving circuit) are 2SC3461's. They would probably be a good replacement for the ECG164's, for directly driving the grids of a Class B modulator. -- -Geoff/W5OMR 2SC3461NPN Triple Diffused Planar Type Silicon Transistor 800V/8A Switching Regulator ApplicationsSANYO NPN Triple Diffused Planar Type Silicon Transistor 2SC3461 800V/8A Switching Regulator Applications Features · High breakdown voltage and high reliability. · Fast switching speed (tf : 0.1µs typ). · Wide ASO. · Adoption of MBIT process. Package Dimensions unit:mm 2022A [2SC3461] Specifications Absolute Maximum Ratings at Ta = 25°C Parameter Collector-to-Base Voltage Collector-to-Emitter Voltage Emitter-to-Base Voltage Collector Current Collector Current (Pulse) Base Current Collector Dissipation Junction Temperature Storage Temperature Symbol VCBO VCEO VEBO IC ICP IB PC Tj Tstg Tc=25°C PW300µs, Duty Cycle10% 1 : Base 2 : Collector 3 : Emitter SANYO : TO-3PB Conditions Ratings 1100 800 7 8 25 4 140 150 55 to +150 Unit V V V A A A W °C °C Electrical Characteristics at Ta = 25°C Parameter Collector Cutoff Current Emitter Cutoff Current DC Current Gain Gain-Bandwidth Product Output Capacitance Symbol ICBO IEBO hFE1 hFE2 fT Cob VCB=800V, IE=0 VEB=5V, IC=0 VCE=5V, IC=0.6A VCE=5V, IC=3A VCE=10V, IC=0.6A VCB=10V, f=1MHz 10* 8 15 155 MHz pF Conditions Ratings min typ max 10 10 40* Unit µA µA * : The hFE1 of the 2SC3461 is classified as follows. When specifying the hFE1 rank, specify two ranks or more in principle. 10 K 20 15 L 30 20 M 40
RE: [AMRadio] Ferroresonant transformer revisited
Looks like a nice Xsistor Jeff. There may be some MOSFETS with 800 or so break down that would work as well. I plan on using the ones that Jim put me on to for the four 813s driver SOME DAY. I need to design a dynamic regulator of some sort for the screen supply of the 813s. (Needs 800V) As of now I waste 100 watts in a bleeder resistor to keep the screens steady. The screen current is low in comparison to the bleeder current so the voltage is pretty stiff. I have thought of a charge regulator for the input capacitor of the pi filter. And maybe one of those HV MOSFET would fit the bill. My theory is to use choke input with high capacitance on the output and then enable a charging capacitor at the input of the filter, turning it into a quasi pi section to keep the voltage up under heavy load. I have never done this but have thought about it for many years. The circuit would look like a pi type filter but the input capacitor would not go to ground. Instead the bottom of it would connect to a tube or MOSFET device that when biased on by a reduction of the controlling sample voltage would allow the input capacitor to charge. A diode place across the tube or MOSFET would allow for the capacitors discharge path. John, WA5BXO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of W5OMR/Geoff Sent: Wednesday, May 10, 2006 3:14 PM To: Discussion of AM Radio Subject: Re: [AMRadio] Ferroresonant transformer revisited John E. Coleman (ARS WA5BXO) wrote: BTW, ,John - those Transistors I got, and told you about (for the solid-state audio driving circuit) are 2SC3461's. They would probably be a good replacement for the ECG164's, for directly driving the grids of a Class B modulator. -- -Geoff/W5OMR 2SC3461NPN Triple Diffused Planar Type Silicon Transistor 800V/8A Switching Regulator ApplicationsSANYO NPN Triple Diffused Planar Type Silicon Transistor 2SC3461 800V/8A Switching Regulator Applications Features · High breakdown voltage and high reliability. · Fast switching speed (tf : 0.1µs typ). · Wide ASO. · Adoption of MBIT process. Package Dimensions unit:mm 2022A [2SC3461] Specifications Absolute Maximum Ratings at Ta = 25°C Parameter Collector-to-Base Voltage Collector-to-Emitter Voltage Emitter-to-Base Voltage Collector Current Collector Current (Pulse) Base Current Collector Dissipation Junction Temperature Storage Temperature Symbol VCBO VCEO VEBO IC ICP IB PC Tj Tstg Tc=25°C PW300µs, Duty Cycle10% 1 : Base 2 : Collector 3 : Emitter SANYO : TO-3PB Conditions Ratings 1100 800 7 8 25 4 140 150 55 to +150 Unit V V V A A A W °C °C Electrical Characteristics at Ta = 25°C Parameter Collector Cutoff Current Emitter Cutoff Current DC Current Gain Gain-Bandwidth Product Output Capacitance Symbol ICBO IEBO hFE1 hFE2 fT Cob VCB=800V, IE=0 VEB=5V, IC=0 VCE=5V, IC=0.6A VCE=5V, IC=3A VCE=10V, IC=0.6A VCB=10V, f=1MHz 10* 8 15 155 MHz pF Conditions Ratings min typ max 10 10 40* Unit µA µA * : The hFE1 of the 2SC3461 is classified as follows. When specifying the hFE1 rank, specify two ranks or more in principle. 10 K 20 15 L 30 20 M 40 __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb
Re: [AMRadio] Ferroresonant transformer revisited
Geoff... If you get a chance would you send along a picture or two of the 450T amplifier? I looked at the tube ratings and I have the iron to get about 3/4 way to the top of the scale. Thanks, Rick/K5IZ
Re: [AMRadio] Ferroresonant transformer revisited
oh, yeah, you betcha! I've seen a few Sola filament transformers at different hamfests. heavy duty comes to mind, as the best way to describe 'em. I have a very light duty one to run my 75A-4. Even a slight change in line voltage, 1v, will cause the PTO to drift frequency, due to the change in filament voltage (B+ is regulated). I found a Sola CVT rated at about 100 v-a at a hamfest. About the size of your fist and weighs maybe 3-4 lbs. It was a modern unit, designed to supply power to a PC. Unlike most of the older version, it is almost completely quiet; I have to really listen carefully to hear it. It does run hot, but that's normal for those transformers. My complaint has always been that they sound like a chainsaw running. With that little xfmr, the A4 is stable as a rock. I use a T-368 PTO as my main station vfo. I stabilised it by running the filaments off a regulated DC supply. Also use it to run mic preamp. Now have stable VFO and hum-free microphone preamp. I'm not sure why a small fraction of a percentage variation in filament voltage will cause such noticeable drift. Without the regulated filament voltage, neither the A4 nor the T-368 pto are stable enough to work 40m cw using a narrow filter. Don k4kyv ___ This message was typed using the DVORAK keyboard layout. Try it - you'll like it. http://www.mwbrooks.com/dvorak/ http://gigliwood.com/abcd/
RE: [AMRadio] Ferroresonant transformer revisited
From: Rick Brashear [EMAIL PROTECTED] A while back we had a lengthy discussion about ferroresonant transformers. I received a lot of excellent advice and help. I have finally been able to apply what I learned... This sounds similar to my experiences with a Sola constant voltage transformer. Is that what a ferroresonant transformer is? Don k4kyv
Re: [AMRadio] Ferroresonant transformer revisited
I believe they are one and the same, Don. Sola is a manufacturer of ferroresonant transformers. Rick/K5IZ Donald Chester wrote: This sounds similar to my experiences with a Sola constant voltage transformer. Is that what a ferroresonant transformer is? Don k4kyv
RE: [AMRadio] Ferroresonant transformer revisited
They are also called CVT (for Constant Voltage Transformer) I think or is there a slight difference that I am not aware of?? John, WA5BXO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Rick Brashear Sent: Tuesday, May 09, 2006 7:03 PM To: Discussion of AM Radio Subject: Re: [AMRadio] Ferroresonant transformer revisited I believe they are one and the same, Don. Sola is a manufacturer of ferroresonant transformers. Rick/K5IZ Donald Chester wrote: This sounds similar to my experiences with a Sola constant voltage transformer. Is that what a ferroresonant transformer is? Don k4kyv __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb
Re: [AMRadio] Ferroresonant transformer revisited
Rick, The ferroresonant transformer is not really resonant at all since the winding that feeds the capacitor is wrapped around a portion of the core that is a saturable reactor. Resonance and saturable reactors don't really go together, but in this case we do have circulating energy in a ferroresonant transformer which consumes about 20% of the VA rating of the device. So for a 1 KVA ferroresonant transformer the power draw when unloaded may be about 200 watts, and this is pretty much a constant. Therefore with a 1 KVA load, the power input would be 1.2 kva. Every line cycle runs the core into saturation, and this creates eddie core losses, heat, buzz, and a quasi square wave output. The output is not a sine wave unless yours has a harmonic filter. Therefore a true RMS meter is needed to accurately measure the AC voltage. These are really neat devices using very old technology. Jim JKO --- Rick Brashear [EMAIL PROTECTED] wrote: A while back we had a lengthy discussion about ferroresonant transformers. I received a lot of excellent advice and help. I have finally been able to apply what I learned to a large ferroresonant transformer that produces about 24 volts AC and when all is said and done the rectified and filtered voltage is about 33 vdc, but drops to an average of about 27 vdc when loaded with a 5 a amp load. The transformer itself is capable of 50 - 75 amps. It's a big one. It seems during the discussions someone made the statement that these transformers had a considerable buzz and I can verify that, it hums like crazy. It was also said that they run rather warm or even hot. That's what I'm curious about. How hot? I left it on for about an hour with no load at all and I can barely put my hand on the top of the core. Is this normal? Should I use a fan with it? It uses a 15 mfd @ 660 vac capacitor to attain resonance and it is new, so I don't suspect a problem there. It draws approximately .9 amp from the ac line when idling, so I don't feel that is excessive. Do they just run that hot? Thanks for wading through all of this. Rick/K5IZ __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb
Re: [AMRadio] Ferroresonant transformer revisited
My own experience with a ferroresonant transformer was with a simple battery charger probably 10A at 14V (140W). I don't recall that it got noticeably hot. If dissipation is about 20% of full load, that would have been about 28 watts - but the unit was bolted to a steel vehicle body, which took away a lot of heat. But this baby that Rick is talking about... 24V at 50 to 75 amps? Assuming 24V at 65 Amps, that's about 1500 watts, and 20% of that would be about 300 watts, which can make something very hot. If the unit was not bolted down to something that would take the heat away, then air convection would have to do it, and the thing could get pretty darn hot. Probably it was just on the floor, or on a wooden bench for this test. I would figure that the unit is designed to be mounted on some chassis and in some cabinet, which would act as a heat sink. If it gets too hot to comfortably hold, then put a fan on it. 300 watts dissipation... Rick, you said it drew about 0.9A unloaded, is that at 240V? That could still be as much as 200 watts dissipation, although I don't know about the phase angle / power factor. One thing to watch out for with a ferroresonant transformer is line frequency. The output voltage is approximately proportional to line frequency, so if you're on a generator, it could vary a bit. And don't expect good charge regulation on 50Hz if the transformer was designed for 60 Hz, and vice versa. I learned that the hard way - and I am glad that I wasn't the one who designed that system, because I might have made the same mistake. There I was looking at the system that had worked OK Fine in the USA, and it just didn't work overseas - and then I noticed that the musical pitch of the AC hum was wrong. Arrrgggh, 50 Hz!!! And the system was going to be used in some places that had 50 Hz power, and other places that had 60 Hz power... Fortunately there were switching battery chargers available at that time, and the project survived. Bacon, WA3WDR - Original Message - From: W5OMR/Geoff [EMAIL PROTECTED] To: Discussion of AM Radio amradio@mailman.qth.net Sent: Sunday, May 07, 2006 7:14 AM Subject: Re: [AMRadio] Ferroresonant transformer revisited Jim Candela wrote: Rick, The ferroresonant transformer is not really resonant at all since the winding that feeds the capacitor is wrapped around a portion of the core that is a saturable reactor. Resonance and saturable reactors don't really go together, but in this case we do have circulating energy in a ferroresonant transformer which consumes about 20% of the VA rating of the device. So for a 1 KVA ferroresonant transformer the power draw when unloaded may be about 200 watts, and this is pretty much a constant. Therefore with a 1 KVA load, the power input would be 1.2 kva. Every line cycle runs the core into saturation, and this creates eddie core losses, heat, buzz, and a quasi square wave output. The output is not a sine wave unless yours has a harmonic filter. Therefore a true RMS meter is needed to accurately measure the AC voltage. These are really neat devices using very old technology. which covers everything *except* what Rick asked, Jim (grinz). How hot is the darn thing -supposed- to get? I, too, wouldn't think that it's hot enough just sitting there, with no load, that you couldn't put your hand on it.. -- -Geoff/W5OMR __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb
RE: [AMRadio] Ferroresonant transformer revisited
Zenith, GE, and Sylvania TV (older tube versions) sets used the Ferro resonant transformer or Constant Voltage Transformer (CVT) that had a special winding with about a 1 to 4mf capacitor across it to saturate the core. This was there answer to the problems of picture shrinkage when people's air conditioner kicked on. They still needed a HV regulator to prevent blooming when the brightness was turned up. The CVT regulated the output voltage for input voltage changes but did not regulate much against load changes. These things are used by carpenters when they need to run a circular electric saw in an area where they need 100ft of extension cord to get power to the saw. When the saw bogs down in wood it draws more current and the extension cord would drop 20 volts or more. The CVT would be placed at the end of the extension cord and the saw plugged into the CVT. The current will drop on the extension cord to 90V but the CVT would hold the voltage up to 120 on the saw. I found these devices to be very useful in the shack to run the receiver and XMIT VFO. I always had to retune the receiver after transmitting and the VFO would drift slightly during XMIT because of the slight filament voltage drop. So I ran separate filament XFMR for the VFO and plugged it into the CVT and ran the receiver from the CVT as well. This ended both problems. I made my CVT from one of the old TV set transformers. One of the manufactures even put theirs on a separate chassis which made it easy for me. These XFMRS had cooling fins around the core and they did get hot. At the time, the US was not into the conservation mode. Here is a google link to a bunch of good info. www.google.com/search?hl=enlr=q=constant+voltage+transformerbtnG=Search SOLO was a major manufacturer of the ones used by carpenters. John, WA5BXO
Re: [AMRadio] Ferroresonant transformer revisited
Jim, Geoff, Bob, John and all who responded, thanks for the excellent information. I scoped the output of the transformer and it is without doubt NOT a sine wave, Jim. Like you said, it is almost a square wave. Bob, I think I have a couple of those old television transformers I pulled years ago when I was in the service business. I'd forgotten all about that, thanks for the memories. Geoff, I am inclined to agree with you about the heat of the transformer. I can touch it, but it would be very uncomfortable if not damaging to my hand to leave it on there more than a very few seconds. I think maybe one thing I should consider is Bob's thoughts on how it's mounted. I'm not sure what service it was in before I got it, but it was likely from a battery charger of maybe even a small arc welder. It was mounted on a heavy 13 X 19 X 1/4 aluminum plate which I'm sure helped dissipate the heat. I have it mounted on a 12 X 10 X 3 aluminum chassis which would not be nearly as effective. The output is very clean. I'm using 3 - 71,000 mfd @ 25 vdc capacitors in series, computing to about 23,600 mfd worth of filtering. There were four of the caps originally, but one went south before I got the piece. Jim, correct me on my math if I am heading the wrong direction. Since I don't have a true RMS voltmeter can't I take the square root of the power dissipated in a resistor across the output to find the actual RMS voltage? Thanks again to all for all of the great response and advice. Rick/K5IZ Jim Candela wrote: Rick, The ferroresonant transformer is not really resonant at all since the winding that feeds the capacitor is wrapped around
Re: [AMRadio] Ferroresonant transformer revisited
Geoff, If the idle power draw is about 20% of the rating, then I figure you can mull that around and conclude how much that is, and how hot that might get. These Ferros's are not noted for efficiency, but if they are loaded near capacity, 80% is doable. It's kind of like a car at 55 mph that might get 25 mpg, and when sitting at a long Texas red light the motor still gets hot, and yet the mpg is zero. Did I answer the question? :-) Jim JKO --- W5OMR/Geoff [EMAIL PROTECTED] wrote: Jim Candela wrote: Rick, The ferroresonant transformer is not really resonant at all since the winding that feeds the capacitor is wrapped around a portion of the core that is a saturable reactor. Resonance and saturable reactors don't really go together, but in this case we do have circulating energy in a ferroresonant transformer which consumes about 20% of the VA rating of the device. So for a 1 KVA ferroresonant transformer the power draw when unloaded may be about 200 watts, and this is pretty much a constant. Therefore with a 1 KVA load, the power input would be 1.2 kva. Every line cycle runs the core into saturation, and this creates eddie core losses, heat, buzz, and a quasi square wave output. The output is not a sine wave unless yours has a harmonic filter. Therefore a true RMS meter is needed to accurately measure the AC voltage. These are really neat devices using very old technology. which covers everything *except* what Rick asked, Jim (grinz). How hot is the darn thing -supposed- to get? I, too, wouldn't think that it's hot enough just sitting there, with no load, that you couldn't put your hand on it.. -- -Geoff/W5OMR __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb
Re: [AMRadio] Ferroresonant transformer revisited
Rick asks: Jim, correct me on my math if I am heading the wrong direction. Since I don't have a true RMS voltmeter can't I take the square root of the power dissipated in a resistor across the output to find the actual RMS voltage? My best answer: E^2=PR, so E = sq root (PR) Yes, but how do you measure P? Another idea: If you have an RF ammeter, this will measure rms current regardless of ac waveform or even dc, then I=E/R so E = IR. Pick a known resistor that will work with the voltage and ammeter you have, and do the calculation. The ammeter must be the thermoucouple type however to get the correct answer. One drawback of the quasi-sine-square wave from a Ferro transformer is that certain power supplies are designed to charge the capacitors to the peak value of the AC voltage, and the designers expect the peak to be 1.414 times the RMS value. With a square wave the peak and RMS are the same, and with a Ferro you might have a value of 1.2 or so. Certain equipment like a SSB linear with a full wave voltage doubler P/S will be way low on peak power when powered from a Ferro versus normal sine wave power. Some of the power inverters on the market that transorm say 12 volts DC to 115 vac do so with a peak voltage of about 150 volts to the load, and dead time either side of the 60 HZ half wave pulse to in effect maintain a workable RMS at 115, and yet peak to about 150 to satisfy capacitor input power supply needs. This can be done quite efficently, and is pretty clever. Regards, Jim JKO
Re: [AMRadio] Ferroresonant transformer revisited
How hot is the darn thing -supposed- to get? For your unit I don't know. I have used hundreds of SOLA Constant Voltage Transformers, of the 250, 500, 1000, and 3000 watt versions. They were of the CVH (harmonic neutralized..SQUARE WAVE) and the CVS (SINE wave type). The 250 watt is impossible to touch in service even with no load. They will remove skin but will work for over twenty years without fail. The 500 watters and the bigger ones being larger (having more mass) can be touched but still run warm. What these things were for was to take a voltage of 90 to 140 volts ac and maintain it at exactly 120 volts. We used them for lightning protection and they worked fine protecting what ever was plugged in; radio equipment and test equipment in the racks. They all draw current when not in use and therefor are a waste of electricity unless they are actually supplying something. Protecting a EIMAC high dollar tube filament would be a great use. We nailed them to concrete block walls vertically for convection cooling. I worked with these things 38 years and don't remember but one capacitor failing in one which was easily replaced and returned to service. Hope this non-answer helps. 73 Mike
Re: [AMRadio] Ferroresonant transformer revisited
Thanks Jim... I am deriving the power rating using a known resistance and the current drawn by that resistance when placed across the output of the supply. R = 8.57 ohms I = 2.9 amps P = I²R P = 8.41 x 8.57 P = 72.0737 E(rms) = square root of (P x R) E(rms) = 24.853 volts Oddly enough, I measured 24.7 vdc on my Fluke 189 multimeter. Rick Jim Candela wrote: My best answer: E^2=PR, so E = sq root (PR) Yes, but how do you measure P? Another idea: If you have an RF ammeter, this will measure rms current regardless of ac waveform or even dc, then I=E/R so E = IR. Pick a known resistor...
RE: [AMRadio] Ferroresonant transformer revisited
I worked with these things 38 years and don't remember but one capacitor failing in one which was easily replaced and returned to service. Hope this non-answer helps. 73 Mike Good input there Mike. Years ago I worked for a lighting company that made ballasts and fixtures for HID lighting in industrial applications such as factories, or airplane hangers. These ballasts were horribly inefficient, and ran hotter then heck. It is amusing because the lamps were very efficient types such as metal halide, or high pressure sodium. To cut costs, the ballast laminations were pretty thick, and then the gaps were closed by welding the core together. Needless to say, core loss from Eddie current loss was high. Then for every technical problem there is a marketing solution. These things were failing right and left. The engineers decided that the most cost effective solution was to use a higher temperature rated magnet wire. They chose class H insulation that could run at 100 C or higher without failure. At that time (1979) there was an old warehouse filled to the rafters with leaking PCB capacitors, and this was in a very environmentally fragile zone that feeds water into an Aquifer that is the main water supply for San Antonio I guess I'm wandering a bit.. Jim JKO -- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.1.392 / Virus Database: 268.5.3/331 - Release Date: 5/3/2006
RE: [AMRadio] Ferroresonant transformer revisited
Rick, what kind of ammeter did you use to measure the current? Jim -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of Rick Brashear Sent: Sunday, May 07, 2006 1:47 PM To: Discussion of AM Radio Subject: Re: [AMRadio] Ferroresonant transformer revisited Thanks Jim... I am deriving the power rating using a known resistance and the current drawn by that resistance when placed across the output of the supply. R = 8.57 ohms I = 2.9 amps P = I²R P = 8.41 x 8.57 P = 72.0737 E(rms) = square root of (P x R) E(rms) = 24.853 volts Oddly enough, I measured 24.7 vdc on my Fluke 189 multimeter. Rick Jim Candela wrote: My best answer: E^2=PR, so E = sq root (PR) Yes, but how do you measure P? Another idea: If you have an RF ammeter, this will measure rms current regardless of ac waveform or even dc, then I=E/R so E = IR. Pick a known resistor... -- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.1.392 / Virus Database: 268.5.3/331 - Release Date: 5/3/2006
Re: [AMRadio] Ferroresonant transformer revisited
Fluke 189. I thought I had an RF ammeter, but I guess I got rid of it or maybe it's lost in the shed... Jim candela wrote: Rick, what kind of ammeter did you use to measure the current? Jim
RE: [AMRadio] Ferroresonant transformer revisited
That's a great idea Jim, about using an RF amp meter for non sinusoidal wave forms or even DC. I've only had three or four of those but never saw two that read the same. I was beginning to think that a thermometer in the dummy load box might be calibrated just as well. HIHI Maybe I just don't have good ones. John, WA5BXO
