Homebrew PCBs

Hi John

I don't know about the ballast question, in my old commercial but 
un-branded box which I got from a rally it matches the tubes.

Mine has 2 x 8W 29cm tubes which are fine for exposing the size of 
boards I make. The clear glass area is 15 x 25cm and the tubes are 
spaced 9cm apart. There's a flat foil reflector behind the tubes. 
Exposure time with Mega pre-sensitised board is about 3 minutes.

Curious what you are going to do for a timer? Mine doesn't have one and 
fitting one is on the list of things to do in the shack.

Regards

Paul G4DCV

On 01/08/2012 07:50, v321uk wrote:
>
> When buying an HF ballast and fluorescent tube does the ballast 
> wattage have to match the tube wattage?
>
> Is it allowable to use an hf ballast of higher wattage that that of 
> the tube e.g. hf ballast 40W tube 12W ?
>
> Can you parallel tubes to an hf ballast intended for a single tube so 
> long as ballast wattage is sufficient ?
>
> I am building a uv-a light box for sensitised PCB exposure and am not 
> sure how many tubes to use.
> I am thinking get a higher wattage than needed hf ballast and say two 
> 8 or 12W tubes so if there is insufficient light I could get one or 
> two more tubes and parallel them.
>
> I usually use the sun for exposure but there has not been much of it 
> here over the last few weeks and I need to make a PCB.
>
> Thanks
> John G3UGY
>
> 
>
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