Hi, I recently got hold of a HP 5345A Automatic Frequency convertor plug-in for my HP5345A Counter. This plugin extends the range to 4Ghz. I got no manual etc with the plugin and it shows the following behaviour
When I input a signal upto around 500Mhz straight into the plugin the display shows correct, but when I put in a signal (from a 1.2Ghz ham radio, the highest frequency source I currently have) it shows 394.00000 when the input frequency is 1294.0000 Mhz
Any ideas if the plugin is fautly or do I have to interpolate the display somehow?