AnsweredAssumed Answered

HP 1980B modification?

Question asked by dtbradio on May 8, 2009
Latest reply on Jun 2, 2011 by algoss
I'm not sure if this is the correct forum section in which to post this, but here goes....

I have an old HP 1980B 'scope used in an RF testing environment (frequencies up to about 30mhz).  I am currently using a BNC splitter on one vertical input channel, from which I derive a signal for a frequency counter, but the counter loads the 'scope input channel and slightly "colors", the 'scope display. I would like to know if there is a semi-easy way to modify the 1980B and add a vertical channel output jack (similar to what is found on the rear panel of the ancient HP 1725A 'scopes), or is there a simple circuit I can build to derive both an un-colored 'scope signal and a counter signal from the original test signal. I am toying with the idea of building an op-amp buffer to place between the "T" and the counter input, but I have no RF design experience, and I've not found anything suitable online thus far. My temporary fix is a 1-meg resistor in series with the input of the counter, with a bypass switch. It seems to do the trick, but I want to eliminate the counter mod in favor of something more universal that can be used at the 'scope input. Of course, if there is a way to add the vertical output jack mentioned earlier, I'd be in great shape.

Thanks in advance for any ideas.