BillO wrote:
Well, here it is and it's not very promising.
This trace is using the 2N2222. The input signal (yellow) is 27MHz @ 5V p-p and the output is 2.5v p-p into 47 ohms. Base is being driven through 360 ohms.
Attachment:
MAP001.png
This trace is using a 2N3904. A tad better with an output of 3V p-p.
Attachment:
MAP002.png
A better transistor will be needed to get closer to your goal.
I honestly don't know how to read that properly. To me, it seems like it's delayed by 5ns with both of them. So I throw an 25 MHz signal into it, it has a propagation delay of 5ns, and so my color signal is delayed 5ns behind what I previously would have had. Monitors are flexible in where the 'start' and 'end' are, so if I started 5ns behind, it would actually think that is where I am starting!
But if you are saying there would be signal loss at 25 MHz, then indeed I would need a better transistor. I am sure I can handle delay, but I cannot handle signal loss.
Generally faster transistors will give you less delay as well. But you could run all the VGA signals through a similar device to make sure there is no phase shift between them.
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