Electronics > Repair
INSTEK spectrum analyzer GSP-827 -6 dBm down than the real value
Adal:
Now I have the demodulation option. ??? Lesson earned, don't acquire "high performance" used test equipment without support or technical information. Maybe Agilent/HP
Best regards
Adal:
Hi.
Some news.
Recently I found the service manual for my machine:
http://www.melchioni.it/moduli/assistenza/ricercaRiservatoDownload/1/?&page=2
For calibration or activate the options, I need a "service password" only available by Instek. :--
So I inquiry for that an Instek Mexican distributor, I´m still waiting for a quote. :-//
Best regards.
G0HZU:
--- Quote ---The signal then gets +16dB gain from U18, an NBB400 MMIC. Looking at this components solder seems to suggest it has been the subject of some attention before!. I plan to isolate it, power it and feed a signal into it and check how much gain it is giving.
--- End quote ---
Looking at the various images of the RF front end I'd guess that the first RF amplifier U18 (marked N4) is an old Stanford Microdevices GaAs HBT part. The logo looks right for the NGA-486 but it's many years since I did any design work with these devices as they went obsolete a long time ago.
RFMD did take over Sirenza a few years ago so the NBB400/NLB400 may be descended from the same technology. The NGA-486 was quite a fragile part and required careful attention to thermal management and also they can be easily damaged from minor overload and transients. I've seen a lot of dead NGA-486 parts in my time :)
xmicron:
Hi Andrew,
Have you managed to solve this issue?
It looks like I am having the same problem!
Regards,
Frank
whipaway:
Sorry to awaken this old thread, but here's the service manual.
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