Hi,
I have a 8753D VNA with Option 006. Unfortunately it stopped working and shows "No IF found: Check R Input Level". The problem is only at 3 to 3.8 GHz output frequency range.
I did all the tests according to the service manual "Source Troubleshooting" and found that:
- Service Menu Test "48" fails
- Source Tune Mode: There is no output signal from the YTO at the low end around 3 and 3.8 GHz
As I already found in other group topics it is a known problem that these YTOs fails at the low end. I tried to buy a replacement one and found one at alltest instruments. I bought it for 700 USD.
Unfortunately if I change the YTO to the "new" one, there is absolutely no output signal over the whole frequency range. If I put my defective YTO back in the VNA it works except the known problem from 3 to 3.8 GHz, off course.
I think the replacement one from alltest is a bad device. Is there anything I can check to confirm this?
best regards
Alex
