[ARC5] Solid State 6AL5

[Richard Knoppow]

    I am not sure which tubes this applies to. I think probably 
thoriated tungsten but not sure of indirectly heated coated 
cathodes. Note that the warm up time of most small rectifiers is 
very short. For instance in receivers with VR tubes I can see the 
VR start to glow before I see the rectifier heater glowing.
    Some engineering tome would probably answer this but it does 
not seem that the idea of HV stripping the cathode is considered 
very important in _most_ low power, i.e. receiver designs. 
Obviously, the radar test set is one where it is and I suspect 
transmitters are the same.

On 2/5/2018 4:43 PM, Bill Cromwell wrote:
> Hi Peter,
> 
> I think the filaments/heaters in those higher power amplifiers 
> have special coatings on them that require being hot *before* B+ 
> is applied. The tubes used by mere mortals like me are not so 
> finicky. We DO have to be aware that the parts downstream from 
> the solid state subs are going to see higher voltages and if they 
> are tubes they are going to see it, 'ready or not'. Most likely 
> to suffer are some of the capacitors that may have already been 
> operating close to their limits. Or resistors that were already 
> being abused.
> 
> Anybody is free to delay onset of B+ with appropriate means. 
> There are probably any number of ways to do it. Just like my 
> means of containment under an inverted washtub in cases that may 
> be catastrophic (see earlier comments in this thread). Things can 
> range from simple to exquisite, Rube Goldberg designs.
> 
> 73,
> 
> Bill  KU8H

-- 
Richard Knoppow
1oldlens1 at ix.netcom.com
WB6KBL