deputy
Joined: 04 Sep 2007
Posts: 1
|
 Posted:
Tue Sep 04, 2007 2:02 pm Post subject:
Cushman CE-15 Spectrum Analyzer |
|
|
I have a Cushman CE-15 Spectrum Analyzer that was working and  recently I noticed signals very weak. When measured they are 30dB down. I have checked the Diodes in the RF attenuator and they check good. I noticed the schematic I got off the repeater builders WEB page that the ref level switch does not correspond to what I measure on the 4 lines going to the RF attenuator. The Cushman I have is black in color on the face.
The switch going to the IF switchable gain and BW check out ok.
I have also checked the 2.1-3.1G oscillator and it seems good level along with the 1900 mhz oscillator and 200mhz. The 189.3 mhz out of the RF attenuator is -30dB like it should be.
I tried to measure the 10.7 out of the RF attenuator with another spectrum analyzer but could not see it. Using a scope and setting the CE-15 to the ref signal at 4 mhz I do see the RF and can check it thru the cards. That all seems ok. I am concerned abou the YIG driver. not sure how to make sure it is delivering teh correct currents to the YIG oscillator.
Any idea where else to look for the 30dB loss? Anyone have a good
service manual on this spectrum analyzer? No RF was transmitted into the Cushman.
_________________
Thanks;
David |
|
FAQ
Memberlist
Register
Profile
Log in to check your private messages
Log in
