good method... if it doesn't misbehave with 2-3 kv on the plate, you're golden. you can see where there was an anode strap around the tube...so used but good. Nice score. If my svetlana 4cx1600B ever dies.. I will have to look for something like this.
good find,Eimac dealer Richardson electronic sell them for around 1900 dollars,even RF parts sell them for premium price....you are lucky man....so i am ,i have 8 of them new in box,and 3 pull outs ,used but good...one SK800 socket with G2 capacitor ,and few socket used without G2 capacitor...for use ,like example where is G2 grounded,for better stability,so cathode is not any more on ground ,but floating,and minus from high volt supply ,screen and grid terminated on cathode....so in that arrangement tube or valve can work even on VHF 144-146 Mhz with very good stability....for HF to 30 Mhz,you can decoupling G2 with ceramic disc ,1nf and 10 nf...6 of each in parallel to lower inductance....also on HF you can use passive grid input....minus voltage supply came via 50 ohms 50 watts non inductive resistor to G1...so amplifier will be stable ,and input SWR are good...you also can implement so called negative feedback resistor from cathode to ground,to improve stability more...around 5 ohms....greetings from Croatia
i forget to say that this valve is one of the best linear tube ever made,maybe the best one....even when working in class B,IMD 3 is around minus 55 db....so in AB1 is even better...there is no cleaner or linear tube than this....4CX350 is close,but not in that power range...regards
@@dynoguy you welcome....in passive grid input,you will have 17db gain...input need around 38volts RMS RF--55volts peak,that correspond to 30w drive to achieve 1500W out....when grid is -55volts,screen 330 volts..plate 3000v .ALPHA 8406 US made use that tube,passive grid and have this voltages and characteristics,they use 6 ohms negative feedback resistor,cathode to ground....so linear need little more drive,around 50w....i didn't use it ,and amp is stable...due to swamping effect of 50 ohm resistor,grid is not few kilo ohms input impedance but 50 ohm,so you have stable amp....that way you lower gain from 30 to 35 db to 17 db,so isolation from input and output is bigger,so no neutralization is needed...and no need to tune input,it is broadband with good SWR.. .i use GM3SEK tetrode board,and there is all voltages you need,automatic over-current protection for all ,grid,screen...,and reset switch..and extremely stable voltages,essential for best linearity....Ian made this board bullet proof-best there is....regards
I have built a HF amp using GI6B triode and very cost effective will give 1000 watts DC output but this is beyond their safe rating I am using 2 GI6B one tube rated at 350 watts plate dissipation they and cost about £20 each plus postage. interesting how you test the tube. The Gi6b needs the heater pins to be cooled .
Very interesting, got me thinking what I should do with some new Eimac 4CX250Bs I have. Good find with the 4CX1500B though, gosh they are a large tube compared to the little 4CX250B... Subscribed.. vk2ccr
Thanks, much appreciated.... Well,...that 1.5kW plate dissipation needs cooling, so it's got to be bigger .... Got plenty of 4CX250/350 too, just not enough time to make something of it ....
@@dynoguy 4cx250b have bad linearity...you can improve that with cathode negative feedback resistor....but 4CX350 have excellent linearity,made strictly for single side band modulation....
@@dynoguy if you turn the machine on, they pop if you turn the machine off they pop. No joke man, these things are pretty garbage and the URT's they are in are a dumpsterfire. The only organization that could feasibly own a URT would be one that cares nothing about cost due to the insane maintenance requirements and parts replacement. Aka the US Navy
Yes, sometime it's just luck, that one came from ebay for just a few £, the seller obviously did not know what he's selling. Never seen transmitting tubes at a car boot, but last summer i bought a Racal 9009 modulation meter for almost nothing
That's a good one, need to remember that. .... However, at your end of the world you might just fry one or two kangaroos, over here we have weird people calling for a decontamination squad when they just think they've seen an antenna, because of all this deadly radiation coming out of it......but sadly it does not solve my rabbit plague, no matter how much power i apply,...:-) ...does anyone know the resonance frequency of wild rabbits ? ...
We use to be able to sit in the back yard and pop off the rabbits with the .22, now we have to go to the country and do it, we don't seem to have the propagation police issues here, my mates are the radio inspectors so now I can't refer to them as my mates anymore.
@@dynoguy is not working I did try about 5 times. I have a question ; what about the current that is flowing trough the grid and screen ? is there a problem to destroy those elements if the anode takes 1 A or so ?
good method... if it doesn't misbehave with 2-3 kv on the plate, you're golden. you can see where there was an anode strap around the tube...so used but good. Nice score. If my svetlana 4cx1600B ever dies.. I will have to look for something like this.
good find,Eimac dealer Richardson electronic sell them for around 1900 dollars,even RF parts sell them for premium price....you are lucky man....so i am ,i have 8 of them new in box,and 3 pull outs ,used but good...one SK800 socket with G2 capacitor ,and few socket used without G2 capacitor...for use ,like example where is G2 grounded,for better stability,so cathode is not any more on ground ,but floating,and minus from high volt supply ,screen and grid terminated on cathode....so in that arrangement tube or valve can work even on VHF 144-146 Mhz with very good stability....for HF to 30 Mhz,you can decoupling G2 with ceramic disc ,1nf and 10 nf...6 of each in parallel to lower inductance....also on HF you can use passive grid input....minus voltage supply came via 50 ohms 50 watts non inductive resistor to G1...so amplifier will be stable ,and input SWR are good...you also can implement so called negative feedback resistor from cathode to ground,to improve stability more...around 5 ohms....greetings from Croatia
i forget to say that this valve is one of the best linear tube ever made,maybe the best one....even when working in class B,IMD 3 is around minus 55 db....so in AB1 is even better...there is no cleaner or linear tube than this....4CX350 is close,but not in that power range...regards
Good info,...thank you
@@dynoguy you welcome....in passive grid input,you will have 17db gain...input need around 38volts RMS RF--55volts peak,that correspond to 30w drive to achieve 1500W out....when grid is -55volts,screen 330 volts..plate 3000v .ALPHA 8406 US made use that tube,passive grid and have this voltages and characteristics,they use 6 ohms negative feedback resistor,cathode to ground....so linear need little more drive,around 50w....i didn't use it ,and amp is stable...due to swamping effect of 50 ohm resistor,grid is not few kilo ohms input impedance but 50 ohm,so you have stable amp....that way you lower gain from 30 to 35 db to 17 db,so isolation from input and output is bigger,so no neutralization is needed...and no need to tune input,it is broadband with good SWR.. .i use GM3SEK tetrode board,and there is all voltages you need,automatic over-current protection for all ,grid,screen...,and reset switch..and extremely stable voltages,essential for best linearity....Ian made this board bullet proof-best there is....regards
I have built a HF amp using GI6B triode and very cost effective will give 1000 watts DC output but this is beyond their safe rating I am using 2 GI6B one tube rated at 350 watts plate dissipation they and cost about £20 each plus postage.
interesting how you test the tube. The Gi6b needs the heater pins to be cooled .
What a find👍
yeah,...looks like a good bargain, how's the mill doing ?
Very interesting, got me thinking what I should do with some new Eimac 4CX250Bs I have. Good find with the 4CX1500B though, gosh they are a large tube compared to the little 4CX250B... Subscribed.. vk2ccr
Thanks, much appreciated.... Well,...that 1.5kW plate dissipation needs cooling, so it's got to be bigger .... Got plenty of 4CX250/350 too, just not enough time to make something of it ....
@@dynoguy 4cx250b have bad linearity...you can improve that with cathode negative feedback resistor....but 4CX350 have excellent linearity,made strictly for single side band modulation....
4cx250b need 25 ohms negative feedback resistor ,cathode to ground to improve linearity much ,from --22 to --38 db....IMD3
The navy still uses these, I just installed 6 in the HF transmitters on a destroyer
It is still a rather cost effective option if you want high power outputs and if you treat them well they last a very long time
@@dynoguy if you turn the machine on, they pop if you turn the machine off they pop. No joke man, these things are pretty garbage and the URT's they are in are a dumpsterfire. The only organization that could feasibly own a URT would be one that cares nothing about cost due to the insane maintenance requirements and parts replacement. Aka the US Navy
LOL,... well, i think that's rather a design problem of the PA, these tubes don't go pop just by design.
@@dynoguy no I know, I'm just venting. These are my job and I hate them.
That's interesting they are still used. It must be in an older destroyer with a URT-23.
great vid though iv no clue at all lmao .your door stop i can hear it talking,saying come see whats inside me ;) use a sawsall....... lol
Thanks, ...good idea, perhaps i should take it apart, and film it of course ...:-)
i bought on of these unused for one English pound from a car boot sale . it was rather a funny story getting it lol
Yes, sometime it's just luck, that one came from ebay for just a few £, the seller obviously did not know what he's selling. Never seen transmitting tubes at a car boot, but last summer i bought a Racal 9009 modulation meter for almost nothing
Have you considered a project for this tube yet?
No i did not,....as said somewhere in the video, it's a bit pointless with our 400W power limit, which to my knowledge is the same as your's.
We run legal limit in vk, we just don't refer to which countries limit it is.
That's a good one, need to remember that. .... However, at your end of the world you might just fry one or two kangaroos, over here we have weird people calling for a decontamination squad when they just think they've seen an antenna, because of all this deadly radiation coming out of it......but sadly it does not solve my rabbit plague, no matter how much power i apply,...:-) ...does anyone know the resonance frequency of wild rabbits ? ...
We use to be able to sit in the back yard and pop off the rabbits with the .22, now we have to go to the country and do it, we don't seem to have the propagation police issues here, my mates are the radio inspectors so now I can't refer to them as my mates anymore.
Should make good build seen a 1500a7 pump out 5000 kw but the plate current 4500
Hello I need some info, can I send you a personal mail ? thanks
You certainly can,.. email is in the about section of my channel and at the end of later videos
@@dynoguy is not working I did try about 5 times.
I have a question ; what about the current that is flowing trough the grid and screen ? is there a problem to destroy those elements if the anode takes 1 A or so ?
Di jual.berapa
English, please