Glad the vacuum cap isn’t too expensive. Probably be a bit much with shipping. Im in over my head. Maybe i can do a fixed frequency. I have just the frequency in mind too. A guy that jams up the airwaves 24/7. He’s really far away. Itd be so cool to finally make contact. Local doesn’t count to me.
I love this old tech. I have a 5C/450A which is similar but even larger. I haven't tested it, I must one day. I also have a beautiful 4212E triode, but sadly when I tested it, it had very low emission.
We have built an amplifier what using a pair GU-81M, it works great even on 10 mters, it can output 2200W+ on 10 meters, the output capatance it is not problem, you can use a roller inductor ,
Sweet dude! I just bought 4! Didn’t expect id need vacuum caps and vacuum isolators. And the regulated 2kv caught me kinda off guard. I want to avoid silicon as much as possible for emp reasons
I built a HF amp using 2 x 813's they needed 10 volts @ 10amps and difficult to get them to work on 10 meters. about 600 watts. My latest project was reverse engineering a Heathkit SB200which was using 572B tubes to Russian pulse radar ceramic UHF tubes, GI6B x2 or I could have used GI7B's . the heater is 12 volts @ 2 amps each and with 2.4kv and about 20 watts of drive will give 800 watts of carrier on 10 meters where as 813 x2 and 100 watts only gave 600 watts. the GI6B's are very cheap just make a hole in the chassis 36mm and clamp with a cap clip. They are triodes
use roller inductor replace the fixed inductor and replace variable capacitor (plate tune) use fixed capacitor on higher band(21MHz or higher) no extra fixed capacitor. I'm sure you will get same power in 10m as low band
In my experience, the 813 can work well at 10 meters. It can still work even at 6m. The problem is that the minimum capacitance of the plate capacitance of the PI network we use is too large. This is not a problem for vacuum tubes with relatively small output capacitance, but it is a big trouble for vacuum tubes with large output capacitance such as 813, GK-71, and GU-81M. They will drop sharply in the output power of the band of 21MHz or above, the plate is red...., our solution is to use rolling inductor tuning, just like Henry's power amplifier, the plate tuning capacitor uses a fixed capacitor below 21MHz, and above 21MHz directly uses the output capacitor of the tube to act as a role, in fact, there is no real independent plate tuning capacitor in the slot. Here's how we worked. The results are very good. Also, I'm not interested in any pulsed emission tubes, the main thing is bad linearity. That's why any commercial amplifier doesn't use this type of tube. Their only advantage is that they are cheap
It's a shame to have to decommission them. 😮 I note that Perian Marcel YO6PMX, used a 4:1 balun for the input impedance to bring the tube impedance down from 2k Ohm to 500 Ohm.
I wanna build one with the only one GU i have: but indeed all points to consider....... and what a nice Delta power supply that is, from our Dutch hams in Zeeland! 73 pe1jas
i have an amplifier with a pair of gu81m the amp was amazing (cost me only 400€) yeah it's has some disadvantages like high heater current...also need relatively complex in/output π network for work....but still worth it....provide 3100W PeP on 160meter and 1900W in 10 meter ...and the biggest advantage's is about this capable to run like 24/7 in full power....i using a 10KVA 3 phase HV trafo....no multiplier or else straight 2 way rectifier and a huge cap on anode side.... and all voltage has an individual linear regulator on them....works well but few issues the amp is big currently living in the rack cabinet.... luckily the amp is relatively quite.... currently i building an HF amp with 2 GU78B i interested for the result....thx the video anyway
I would not use vacuum relays for band switching. The lead length within the Pi circuitry of that amplifier is far to long for eficient use on the high bands,
@@thewtfwould love to see the schematic of it, obviously if possible, I've got a pair of these beasts a friend of mine got when escaping from Russia and I would love to see how much winding I would need to do to get an output transformer for these ahah
Im thinking of making and selling tube amps like this. With how incredibly expensive transistors are and for some reason large tubes, i got these. Dont care about efficiency much, mainly power output
A beast of a valve and the power supply. Very interesting video thanks for sharing Justin...David M0DAD
Glad the vacuum cap isn’t too expensive. Probably be a bit much with shipping. Im in over my head. Maybe i can do a fixed frequency. I have just the frequency in mind too. A guy that jams up the airwaves 24/7. He’s really far away. Itd be so cool to finally make contact. Local doesn’t count to me.
Not using vacuum relays. Looked em up and it hurt LOL. They are beautiful tho. I hope I get to play with them one day.
I love this old tech. I have a 5C/450A which is similar but even larger. I haven't tested it, I must one day. I also have a beautiful 4212E triode, but sadly when I tested it, it had very low emission.
Another reason to stick with grounded grid, especially for a newbie amp builder...
1.5KW!!! Bro! Im happy to get 500! For the price of amps! I just want CB.
Can we make a HV regulator with tubes? I don’t want to use silicon if I can avoid it.
We have built an amplifier what using a pair GU-81M, it works great even on 10 mters, it can output 2200W+ on 10 meters, the output capatance it is not problem, you can use a roller inductor ,
Sweet dude! I just bought 4! Didn’t expect id need vacuum caps and vacuum isolators. And the regulated 2kv caught me kinda off guard. I want to avoid silicon as much as possible for emp reasons
I built a HF amp using 2 x 813's they needed 10 volts @ 10amps and difficult to get them to work on 10 meters. about 600 watts.
My latest project was reverse engineering a Heathkit SB200which was using 572B tubes to Russian pulse radar ceramic UHF tubes, GI6B x2 or I could have used GI7B's . the heater is 12 volts @ 2 amps each and with 2.4kv and about 20 watts of drive will give 800 watts of carrier on 10 meters where as 813 x2 and 100 watts only gave 600 watts.
the GI6B's are very cheap just make a hole in the chassis 36mm and clamp with a cap clip.
They are triodes
Did you make your GI6B amp grounded grid?
use roller inductor replace the fixed inductor and replace variable capacitor (plate tune) use fixed capacitor on higher band(21MHz or higher) no extra fixed capacitor. I'm sure you will get same power in 10m as low band
In my experience, the 813 can work well at 10 meters. It can still work even at 6m. The problem is that the minimum capacitance of the plate capacitance of the PI network we use is too large. This is not a problem for vacuum tubes with relatively small output capacitance, but it is a big trouble for vacuum tubes with large output capacitance such as 813, GK-71, and GU-81M. They will drop sharply in the output power of the band of 21MHz or above, the plate is red...., our solution is to use rolling inductor tuning, just like Henry's power amplifier, the plate tuning capacitor uses a fixed capacitor below 21MHz, and above 21MHz directly uses the output capacitor of the tube to act as a role, in fact, there is no real independent plate tuning capacitor in the slot. Here's how we worked. The results are very good. Also, I'm not interested in any pulsed emission tubes, the main thing is bad linearity. That's why any commercial amplifier doesn't use this type of tube. Their only advantage is that they are cheap
Beautiful. Such a shame to tear down.
It's a shame to have to decommission them. 😮 I note that Perian Marcel YO6PMX, used a 4:1 balun for the input impedance to bring the tube impedance down from 2k Ohm to 500 Ohm.
I wanna build one with the only one GU i have: but indeed all points to consider....... and what a nice Delta power supply that is, from our Dutch hams in Zeeland! 73 pe1jas
He should sell you that amp before it is pulled apart.
i have an amplifier with a pair of gu81m the amp was amazing (cost me only 400€) yeah it's has some disadvantages like high heater current...also need relatively complex in/output π network for work....but still worth it....provide 3100W PeP on 160meter and 1900W in 10 meter ...and the biggest advantage's is about this capable to run like 24/7 in full power....i using a 10KVA 3 phase HV trafo....no multiplier or else straight 2 way rectifier and a huge cap on anode side.... and all voltage has an individual linear regulator on them....works well but few issues the amp is big currently living in the rack cabinet.... luckily the amp is relatively quite.... currently i building an HF amp with 2 GU78B i interested for the result....thx the video anyway
If you can optimize the pi network as I said above, you will get at least 2800+ W in 10m
I would not use vacuum relays for band switching. The lead length within the Pi circuitry of that amplifier is far to long for eficient use on the high bands,
Yes, some of them are a bit long
Thanks 😁
Sell the GU81 amplifier your friend built. People would want it. Don't destroy it. No sense in that mate.
Dont worry I did not scrap it the end! Kept it and got it working nicely! Works very well
@@thewtfwould love to see the schematic of it, obviously if possible, I've got a pair of these beasts a friend of mine got when escaping from Russia and I would love to see how much winding I would need to do to get an output transformer for these ahah
Im thinking of making and selling tube amps like this. With how incredibly expensive transistors are and for some reason large tubes, i got these. Dont care about efficiency much, mainly power output
А почему ? Линейность оставляет желать лучшего ? Вы просто не умеете их готовить
ebay sell the project to free up space
Not the best but cheap easy and robust. I spent 230 bucks to get four. I wanna make a nasty powerful amp
Stick with the tubes made in the country only capable of bombing wedding parties!