finding the right tube

[kb3rdt]

ok how about this don't know this help or not but I can't beleave your passing up the viker 2 but here is a little amp only do bout 125 watt AM for a 813 i like 2 give you more if you need it always build bigger push pull amps are better then just one tube but that's all up to you!

http://www.raibeam.com/zl1axb/813_amp.html


                                                                                                                                 

[kb3ouk]

Hit rewind.

The issue was that the OP has a limited power audio amp that he wants to use for modulation? Did I get that right??

These days, if ur going to use a solid state amp with a reversed transformer for modulation, no reason to limit urself due to amp power. There are a ton of ultra powerful solid state amps out there at rather low prices. So no reason to limit oneself due to a specific amp that is on hand when ur going to do a homebrew transmitter that will take a lot of time and effort and possibly $$ to build. Imo.

                        _-_-bear

i have a 100w amp, so i just didnt want anyone to sugegest a tube or combination of tubes that put the plate input over 200w, which is the power level i'm looking at, between 120 and 180 watts. thats why i think i'll go with the single 813.

[kb3rdt]

but why you want 20 to 80 watts more there is no gain there! now your telline me your radio is putting out 100 watts so why you going for 180 watts! now i want to know you building an rf amp or a audio amp push pull 811A or want more 572B's more 813's!

[kb3ouk]

i have a 100w AUDIO amp, that i want to use to modulate a 120 to 180w RF amp, that i want to build using a single 813.

[KC4VWU]

He's wanting to roll his own and experiment, which is quite understandable.

Build the RF deck and the P/S on separate chassis. Plan the RF deck out so that later on, you could add a second 813, and also overbuild the P/S from the start so that it can deliver the necessary current for 2 tubes. Makes it easier to upgrade later on.

Whatever you choose to do, take your time and do it right, learn, and have fun.  


73, Phil

[WQ9E]

 i have a 100w amp, so i just didnt want anyone to sugegest a tube or combination of tubes that put the plate input over 200w, which is the power level i'm looking at, between 120 and 180 watts. thats why i think i'll go with the single 813.

You can run a 4-1000A at only 200 watts input, IF you want.  It is fine (within reason) to use a tube with more capability-just not one with less.  For example, the 813 you are considering is rated up to 200 watts input for grid modulated service and twice as much for traditional class C with high level modulation.  So in traditional terms it is a "400 watt tube".

If you have (or someone offers you a good deal) tubes that are capable of more input you are better off with more emission capacity (extended service at your required power level) and more plate dissipation (bad things do happen and that reserve capacity is a positive).

[kb3rdt]

put 1500 volts on per 813 will give same as a single put a variable power supply on it if you want more you'll have it but that is up to you if you don't you will be sorry!