The old mobile tube amps ?Broad Band? Tunning?

[ElectronTubesRule]

Ok so the ones that did not have tune and load controls how did they do it? How did they get read of the need for tune and load controls? I would like to try and to build one if I can work out a simple auto tuning circuit.


Obviously I do not want to be driving down the road and having to mess with tune and load controls. I know I could buy a solid state auto tuner and stuff it in their but I would prefer to do something cheaper with off the shelf parts if it can be done.

The power supply is not an issue that is the easy part really. I am figuring 300W SSB and 100-150W on all other modes.

 

[Atlasta]

Several of them - I'm thinking along the lines of the D&A Scorpion, or the old Courier or KRIS amps- did have tune and load controls, but they were adjustable via rear-panel screwdriver pots. Some of them had internal controls. Sort of a set it and forget it arrangement.

As I recall most of these amps were pretty much AM only, that is they had no provision for an SSB delay circuit.

Some of those old mobile amps had considerable size and heft to them. Of course that was back when vehicles were made of metal and they had a lot of under dash space!

The only mobile tube amp I ever had was a Lafayette HA 250. Cute little thing, good for about 100 watts on a good day.

 

[ElectronTubesRule]

I do not mind size. My Toyota Camry and Buick LeSaber both have large trunks. My trunks are empty or close to it 99% of the time....I keep a change of close, a jacket and few hand tools in my trunks nothing major no golf clubs, no dead bodies, so space in the trunk is normally not at a premium. I would not ever want to mount a tube amp in the passenger space because I almost always have to have space for myself and my 3 kids and at least one other adult or one other kid on a moments notice. So it has to be out of sight which precludes manual tuning every-time I change freq.

I do not drive and talk much well not since I gave up CB due to filthy language randomly coming out of the speaker. So I am not a heavy user. I am sure this will change once I take my test and become an amateur.

At the low power levels I am talking about could I use pre-built tuned inputs and use mica caps and toroidals to get the Q I need for each band and call that good enough? Each band is kind of narrow if I aim for the high enough Q in each individual tank circuit that might give me enough wiggle room to not need to do the tune and load dance! So if I made it a 3 band amp I would need to have 3 separate switched tank circuits but at low enough power it might be doable????

 

[Captain Kilowatt]

those old mobile tube amps were built back when the 11m band was only about 290 KHz. Fixed tuned circuits would handle that range fine. IMO mobile tube amps are ridiculous due to power supply requirements, cooling issues, and fragility of the tube elements. Leave tubes at home where they belong.

 

[ElectronTubesRule]

Fine Rain on my parade......LOL Transistor amps are easier to build and so much more friendly to wide bandwidth coverage.....LOL

I talked with someone that I would love to meet someday he a well established home brew Amateur. He suggested that if I had a Q of 4 or higher on each individual tank circuit I could in fact do what I want with out doing the tune and load Waltz.....Obviously still not the ideal.. So I will put this on the back burner and focus on my main goal.

Once I get some head way I will take photo as I go to document things. With band, religious ed, sports, work , looking for more work and being way too tight lately on funds things are going slowly!!! Sorry for the run on I know I see it too!LOL

I think I am going to make up my diode board, cut the secondary off one of my two MOT's and use it from my 12 volt power needs. Well 12-13.2 volt needs. I made one already as a proof of concept but at that time I did not have the ability to measure current directly. So I need to make sure it has the required current or upgrade my wire to allow for more current at that voltage.

So I am going to do what I can with what I have and build each section one at a time and set the finished sections or modules aside until I have them all done then start of the placement of the modules.

 

[Kamikaze]

Check out the Central Electronics 200V and see how they did it.

 

[Shockwave]

Those older mobile tube amps were fairly inefficient for the output power they make. By the time you deal with the DC to DC converter with its transformer being driven by a square wave and the tube filaments, they can draw twice the input power as a solid state amp for the same output power.