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Old 15th Feb 2012, 12:22 am   #2
Sean Williams
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Join Date: Feb 2005
Location: St.Ippolyts, Hitchin, Hertfordshire QRA IO91UW
Posts: 3,517
Default Re: Valve Linear Amplifier project

Quote:
I will have to lay on the additional 10V 5A for the 'space' heater and voltage doublers for more anode volts. I will build the tank for all the Watts
This will be ok for heaters, and a doubler on the PSU might work - first area of concern will be "is the HV supply stiff enough to allow for good IMD performance?"

Building the "Tank" or anode circuitry for "all the watts" is fine in theory, I am guessing you will be going for a pi network as the output?

If this is the case you will almost certainly come a cropper

The anode impedance of the 807 amp will differ greatly from an 813 amp - your pi network will need to transform Rp to 50r or there abouts

Assuming 4x 807, in full abuse mode

80ma@700V per valve

320ma total anode current @700V

Rp will equal somewhere near 2200r

Single 813 1500v on anode - 180ma anode current

Rp will be somewhere near 8000r

Thats a massive difference, and will doubtlessly require a redesign for the anode circuitry.....

Sorry to be the bearer of bad tidings.....

Sean
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