Travelling Wave Tube Amplifier

yeah this is an interesting device i thought it's worth having a look at it's a traveling wave tube amplifier and this is designed to amplify in the micro wave region the traveling wave tube uh doesn't work in the way of transistors and things it actually uses uh basically a linear accelerator or a cathode ray to do the amplification so good to have a look and see what's actually inside these are the waveguides uh in and out so uh it doesn't create the actual wavelength what it is taking it takes in a a weak signal and produces a larger signal so it can actually be used as a transmitter or a receiver as traveling wave tubes go this is quite a small device it's also quite low power it's only one watt output its midpoint is nine gigahertz and it's and the anode part is only running at 2.7 kv um the way that it's constructed is there's an electron gun inside here and that there's a beam then we'll travel up through a tube here and this point is where the anode is on the on the tube itself so we can have a little look inside um if we take parts off i've understood all the screws already this is our heatsink on our anode and take this part off you can see there's actually a center tube in here which is actually a lot of magnets along here the function of the magnets is to keep the beam collimated in our electron gun assembly is in this end of the tube in here and i have actually taken the the whole tube out of here already so unfortunately taking the actual electron tube out of this it kind of broke they they tend to be potted in with silicon and the likes like this one so it wasn't easy to remove um but basically it's it sits inside like inside this tube that way and this is the electron gun assembly here and we have a long tube here with a helix inside it and this is the target anode at this end you can see this was never really intended to be serviceable to the point there's not even a socket fitted onto the actual uh traveling wave tube itself here see where this heatsink was attached to the the anode here because the impact of the electrons here would be would generate some heat the voltages only 2.7 kv so it wouldn't produce x-rays but uh traveling wave guides running at 50 kilovolts and the likes will produce x-rays as well as the construction is that you can actually see these two waveguides come in and sit roughly about here on the um this little ex tube here this is like a graphite coating i'm not sure it might be for attenuation so the way it seems to be arranged that this works is you've got your electron beam traveling across here under the the field from the anode cathode you have your wave coming in and and coupling on to this helix here the wave obviously traveling faster than the electrons but it's slowed down with this helical coil here and therefore influenced by the electrons traveling across here to amplify it so have a little closer look at the sample this so if we just disconnect or take away the glass outer casing here you can see the little supports and the helical coil in there that is very fine so it's our anode end there and this is our coil here and our electron gun assembly is in here so very similar electron gun to a cathode ray tube so you can can see that the this material here which can sometimes be beryllium beryllium oxides uh it tends to be a lot whiter i don't think this is as big as ceramic this is something i suspect is maybe berlin oxide as a heat sink and uh that is is different so i don't think there's a risk on this this little thing here i think is attenuation for the for the actual wave guide itself or the amplified beam because you'll get reflections and this is an absorber to stop reflections coming back down to the inputs part of the waveguide you can just make out the helix spring in there there are a little few connections in here that are worth looking at um if i trace these through there there's actually a connection to the um the helix the coil here um which does go down onto one of the pins here and there's also another connection to this point here so there may be some focusing arrangement being done to the beam before it actually exits the the gun at this point um it's also interesting here's a little this is the the getter for the for conditioning the vacuum here and um it's actually looks rather normally these are inductively uh fired but this one actually looks like it's physically connected in a loop with the two connections that could fire just by passing a current through it okay and just finally as i pointed out these magnets here if we take the anode and apart so this is actually the connection to the anode and it's connected to the chassis um interestingly enough this is the waveguide okay exact so the uh the traveling wave tube sits inside here and it goes through the center of that and these are obviously shielding connections and the rest of the magnets are all in here as well only one last point uh obviously for setting up these you can adjust the tension on the actual magnet column there's adjustments here and there's also a screw here so you can obviously bend this to focus the beam and another thing that came across if you can make it out in focus it is this there's a little little magnet there's like a little shunt on top here so there's obviously some fine tune adjustment by placing the magnets along here too okay i hope you found that quite interesting

Channel: tuopeek

Views: 8,467

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Id: I-DlgOoz978

Length: 7min 44sec (464 seconds)

Published: Tue Oct 27 2020