[Amps] filament instant heating query / simple remedy

[Roger (K8RI)]

On 6/17/2012 10:22 AM, Jim W7RY wrote:
> -Has anyone tried an approach like Carel, PC5M, with a microprocessor
> -controlled soft start for the filament.  The microprocessor controls an
> -optical triac driver  The triac is turned on and off over an increasing
> -portion of the line AC cycle until full on is reached. His
> -microprocessor program does this in 100 sec.  It is designed only for
> -soft start and does not do any regulation of the filament voltage after
> -full output is reached.

You don't need a microprocessor to control the triac. Just an RC network 
plus a diac.
They are noisy as all get out while ramping up and you only need about 4 
seconds for amateur HV supplies and even the Kalifornia KW QRO filaments.

>
> -David
> -KW4DH
>
> Oh PLEASE!
>
> Just put a resistor in line switched with a relay!  This is not rocket
> science!

  No contacts to clean, simple, and cheap!  Emtron amps use the Triac to 
ramp up the voltage for the whole amp and it works very well.

73

Roger (K8RI)