I am working on rebuilding a home brew 4/572B amp now (new PS and a few T/R switching changes)
She will be full limit maybe a smidgen's less when finished (PS/3200v B+/no load) and she won't sag much either...
Hey QRN,
Can you get away with running the broadcast plate xfmr into a cap input filter for a few more volts? That might put it in the ballpark for a GS-35B or 2 instead of screwing around with all those sockets and filament power.
Yeah but I like the glow of glass tubes. : Like they say, glass has class.
The thing is, I have all the parts on hand to use 4-400's or 3-500Z's.I figured I would build it up using the 4-400's that I already have and get it working first and then maybe buy some 3-500Z's. It should just be a matter of readjusting the taps on the tank circuit.Four 3-500Z's have the same plate dissapation as a pair of 4-1000's and I would need to buy a socket and filament transformer and possibly a plate transformer for the 4-1000 not to mention the 4-1000's themselves.I can make up to 9000 volts but at only about 0.5 amps CCS and it would have to be a capacitor input supply. I already have the sockets as well as the chimnies and stacks for the 4-400/3-500Z's and a bunch of tubes along with the proper filament xmfr and a plate xmfr good for 1.2 amps CCS that will give me a 3100 volt good stiff PSU using choke input.In the b'cast TX the power supply was 3200 volts unloaded and only dropped to 3100 at a tad over 1 amp load,not too shabby for a HV supply.A pair of 4-1000's would be nice but a little too much cash for me right now. The amp is going into a standard Hammond 19 inch rack cabinet 42 inches high and will be built in separate levels making it easy to later change the RF deck if I so decide.
Yeah, I checked and double checked the heights of my chimneys and they will fit either tube. I also have the fiberglass stacks to fit on top of the chimneys to direct airflow straight up over the anode connection and out the top of the cabinet. I'm not too worried about the current rating of the transformer,it was meant for 100% continous duty forever with it's 1.2 amp CCS rating so peaks of 2 amps ICAS should not hurt it a bit.It weighs in at 85 pounds all by itself BTW. As for the tubes, they will be in GG service and should work resonably well 20m and down which is really what I am after. Anything above that is gravy.Yes,there are better ways to do some things but I am going to use what I have on hand and if/when a problem comes up I will deal with it in whatever manner it takes to solve it be it technical changes or monetary comittment. I may even just start off with a pair of tubes and see how things go.The RF deck I have from the old b'cast TX has four sockets installed below chassis level and a ready made airflow path under the chassis.It is a piece of cake to simple block two socket holes and just run a pair for starters.I am just in the process of cleaning out the basement and moving things out to the barn and with each large storage box I dig out I find yet more parts.After I get them all together I will have a better handle on just what I will do.