As soon as I can get an area set up to do videos, I will be showing step by step how to build Tetrode amps along with how to build some of the necessary items of test equipment and how to get the most out of MOT's on my channel.
very istructive and easy way to understand how a valved amp works but its not really that easy .pay attention to High voltage risc .beginners may burn before seeing the neeedles raising . always shrt cut condensers before use ...they remember always their charge ...lol .tahk you so mach sir .best 73 .best wishes for all radio amateurs .CN8BHA .
Triquint make an RF transistor that runs linear from DC to a few dozen GHz, but they want roughly £680 each for them, and the USA legal limit or something respectable would take 12 or more. I looked at using this particular valve, when I obtained a pair of very old US Navy anode supply transformers that put out 6200 volts CT. Unfortunately the primaries are 105-120 volts AC 60 Hz. I have two of them, so running the primaries in series could work with 230 volts. I used MOSFETs on the primary to dial back the anode voltage. I am trying to use the UK terminology, for VK6CS's sake. I bought a USA made 8877 from an eBay seller in France, and that gave me a lovely output of 1500 watts peak effective power, with the plate voltage dialed back, or the drive power dialed back. Honestly, I am not 100% sure if the primaries on the anode transformers are 95-100-105-110, or how exactly those are wound, to be absolutely certain. I know the previous owner was running three 3-500ZG Chinese tubes. His power supply, was a rather spooky affair. Eventually his wife demanded he dismantle the thing and sell of the 3600-4000 volt anode supplies, lest he or one of his children get into it and light themselves up like the proverbial Christmas tree. I twisted up some coils using seamless extruded copper tubing, which I silver plated using a DC power supply, and some silver plating solution. You wind coils to rival mine! I made VHF jammers when I was back in primary school, and my classmates and I drove the local tele salesmen to madness at the local department stores with them. We would jam all the channels but two watch the salesmen run about changing channels, and then jam those channels. Then we would watch the frantic fun begin all over again. Or range was only about 15 maybe 20 meters. Great primer on making a linear amp! I have been considering buying some old Soviet valves! Now I see one being used! Superb, mate. CHEERS, 73 KI7AQJ Arizona.
Well,almost used. I keep telling myself I'll finish this thing and fire it up. I'll tell you what though... I think I would have been better off with a glass envelope tube or two to keep the blower noise down. Those transformers sound pretty useful, you could series the primaries and parallel the secondaries. You didn't mention the current rating of the secondary winding's but if someone was using them to run 3 x 3-500Gs there should be plenty there. You could put each transformer on a variac to confirm the primary voltage rating if you know what the secondary voltage is supposed to be. But I'm sure you know all that. Good luck with it, 73.
figure on 3800-4kv and 30-32v bias . at that voltage cathode impedance will be about 35-40 ohms . legal limit with ease .. not sure you are going to make it at 2800v . I built using pi input I have messed with a couple of them nice tube . like a super heavy duty 8877 . be sure to run them with filament and blower for 24 hours minimum as with any nos tube . have seen a couple that I couldn't get rid of gas and found there was rust inside
Thanks for the info. I just looked at the spec, it shows 3kV max anode voltage and a transformer that would give around that voltage became available. If it doesn't make 1500W it's no big deal as we're only allowed 400W PEP max. It would be good to get 1kW out of it though... nice round number. I had thought of using an L match circuit on the input just to keep it as simple as possible. I have run it with heater and blower only for 24 hours already, but thanks for the reminder. I'll have to get my backside in gear and get it finished.
VK6CS yes no problem alot of cold war ara russian tetrodes the specs were off . but in military use of that tube they often ran as high as 5kv .. first one i built was off of there specs was a dud never could get over 30% efficiency till i pushed hv up to 3700 loaded then i could achive 50% and thats when i really started askinf questions haha .... good stuff keep the videos coming
Crikey... sounds like I'll be asking lots of questions. If I ever do get it finished I'll certainly post a video or two showing how well/poorly it works. I have made the PA tube mounting/air-box section modular so if it's really poor I can substitute the GS-35 with another tube/tubes. I did wonder about using a glass tetrode or two, this would allow screen grid mod to be applied for AM. And glass tubes look more like real radio.
Lovely video. I understand a bit more about rf tube bias when explained well.
Thank you Sir, Very informative. They way of your presentation is also quite pretty. Hats off to your sir.
+Abdulla Therambathu Thank you for those very kind words Sir.
Thanks you for sharing > Great presentation OM, many 73's
+Nader Omer Thanks for the feedback OM, many 73's to you.
An excellent informative video thanks Steve !
VK6ZMS Hi Martin... thanks for the feedback. I'm glad you enjoyed it.
Oh Man very good, thanks Man...... i am have gs31b hf amplifier.
How connect a grid current meter ? Thank you.
As soon as I can get an area set up to do videos, I will be showing step by step
how to build Tetrode amps along with how to build some of the necessary
items of test equipment and how to get the most out of MOT's on my channel.
If i use 807 , is there any combining bethwen anode and catode?
very istructive and easy way to understand how a valved amp works but its not really that easy .pay attention to High voltage risc .beginners may burn before seeing the neeedles raising . always shrt cut condensers before use ...they remember always their charge ...lol .tahk you so mach sir .best 73 .best wishes for all radio amateurs .CN8BHA .
Thank you Sir... very good points, 73.
شكرا ⚘️كان عندي مشروع استبدال الصمامين طراز
3-500zg
وذلك في الوحدة
AL-82 amplifier
بالصمام gs35b
Triquint make an RF transistor that runs linear from DC to a few dozen GHz, but they want roughly £680 each for them, and the USA legal limit or something respectable would take 12 or more. I looked at using this particular valve, when I obtained a pair of very old US Navy anode supply transformers that put out 6200 volts CT. Unfortunately the primaries are 105-120 volts AC 60 Hz. I have two of them, so running the primaries in series could work with 230 volts. I used MOSFETs on the primary to dial back the anode voltage. I am trying to use the UK terminology, for VK6CS's sake. I bought a USA made 8877 from an eBay seller in France, and that gave me a lovely output of 1500 watts peak effective power, with the plate voltage dialed back, or the drive power dialed back. Honestly, I am not 100% sure if the primaries on the anode transformers are 95-100-105-110, or how exactly those are wound, to be absolutely certain. I know the previous owner was running three 3-500ZG Chinese tubes. His power supply, was a rather spooky affair. Eventually his wife demanded he dismantle the thing and sell of the 3600-4000 volt anode supplies, lest he or one of his children get into it and light themselves up like the proverbial Christmas tree. I twisted up some coils using seamless extruded copper tubing, which I silver plated using a DC power supply, and some silver plating solution. You wind coils to rival mine! I made VHF jammers when I was back in primary school, and my classmates and I drove the local tele salesmen to madness at the local department stores with them. We would jam all the channels but two watch the salesmen run about changing channels, and then jam those channels. Then we would watch the frantic fun begin all over again. Or range was only about 15 maybe 20 meters. Great primer on making a linear amp! I have been considering buying some old Soviet valves! Now I see one being used! Superb, mate. CHEERS, 73 KI7AQJ Arizona.
Well,almost used. I keep telling myself I'll finish this thing and fire it up. I'll tell you what though... I think I would have been better off with a glass envelope tube or two to keep the blower noise down.
Those transformers sound pretty useful, you could series the primaries and parallel the secondaries. You didn't mention the current rating of the secondary winding's but if someone was using them to run 3 x 3-500Gs there should be plenty there. You could put each transformer on a variac to confirm the primary voltage rating if you know what the secondary voltage is supposed to be. But I'm sure you know all that. Good luck with it, 73.
What about a 4CX5000A and forced air cooling.
I've got 1 of those valves, have yet to make an amp with it yet, but it looks promising. Have you made yours yet? if so, how does it perform?
figure on 3800-4kv and 30-32v bias . at that voltage cathode impedance will be about 35-40 ohms . legal limit with ease .. not sure you are going to make it at 2800v . I built using pi input I have messed with a couple of them nice tube . like a super heavy duty 8877 . be sure to run them with filament and blower for 24 hours minimum as with any nos tube . have seen a couple that I couldn't get rid of gas and found there was rust inside
Thanks for the info. I just looked at the spec, it shows 3kV max anode voltage and a transformer that would give around that voltage became available. If it doesn't make 1500W it's no big deal as we're only allowed 400W PEP max. It would be good to get 1kW out of it though... nice round number. I had thought of using an L match circuit on the input just to keep it as simple as possible. I have run it with heater and blower only for 24 hours already, but thanks for the reminder. I'll have to get my backside in gear and get it finished.
VK6CS yes no problem alot of cold war ara russian tetrodes the specs were off . but in military use of that tube they often ran as high as 5kv .. first one i built was off of there specs was a dud never could get over 30% efficiency till i pushed hv up to 3700 loaded then i could achive 50% and thats when i really started askinf questions haha .... good stuff keep the videos coming
Crikey... sounds like I'll be asking lots of questions. If I ever do get it finished I'll certainly post a video or two showing how well/poorly it works. I have made the PA tube mounting/air-box section modular so if it's really poor I can substitute the GS-35 with another tube/tubes. I did wonder about using a glass tetrode or two, this would allow screen grid mod to be applied for AM. And glass tubes look more like real radio.
good show
+Geronemo Bauer Thanks Geronimo.
My boyfriend just got a grounded grid amplifier schematic tattooed on his arm.
I am concerned that your bias diode needs to carry 700 mA at 15V. What diode number will handle that amount of current/power?
au.element14.com/solid-state/1n3313b/zener-diode-50w-14v-do-5/dp/1671488
That'll do it!
use a r'gulator 7815 v for that
What is this sorcery?
Something to do with electrickery...
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