Dear all,
My HP 8562A (3040A5503, Rev: 891012) starts up without any error. However the amplitude calibration at the high end is not correct: the sa reads 10-15 dB low. The 300MHz cal osc reads correct (-10 dBm). Right now I do not suspect the mixer: it was ok some time ago and I am very carefull not to overload the input. So I ordered a TAM: HP85629A (Rev: 870218A). Alas, ignorance has its cost as I suspect this unit to be too old to be useful for my sa. I run the automatic fault isolation routine which stops at test 3: IF Log Check failure. Then I'm advised to dig into the instrument to check the internal 10,7 MHz cal osc. But before any surgery I'd like to know if my TAM is suitable at all for this purpose. I can only find info on the HP85629B, that I, obviously, do not have. Could the A be upgraded to a B?
Any advise is highly appreciated!
Thanks in advance,
Harke ,PA0HRK
My HP 8562A (3040A5503, Rev: 891012) starts up without any error. However the amplitude calibration at the high end is not correct: the sa reads 10-15 dB low. The 300MHz cal osc reads correct (-10 dBm). Right now I do not suspect the mixer: it was ok some time ago and I am very carefull not to overload the input. So I ordered a TAM: HP85629A (Rev: 870218A). Alas, ignorance has its cost as I suspect this unit to be too old to be useful for my sa. I run the automatic fault isolation routine which stops at test 3: IF Log Check failure. Then I'm advised to dig into the instrument to check the internal 10,7 MHz cal osc. But before any surgery I'd like to know if my TAM is suitable at all for this purpose. I can only find info on the HP85629B, that I, obviously, do not have. Could the A be upgraded to a B?
Any advise is highly appreciated!
Thanks in advance,
Harke ,PA0HRK
There were upgrade kits to upgrade an 85629A to an 85629B, however, these were discontinued many years ago. The feature you really need to use is RF Path Fault Isolation, which makes use of an external microwave signal generator tuned to 5, 10, 15, and 20 GHz (prompted by the TAM) to help diagnose problems at frequencies >2.9 GHz.
Have you tried performing a preselector peak (press INT, PRESEL AUTO PK) to see if that causes the signal amplitudes at the high end to return to normal? You can also try manually adjusting the preselector (press INT, PRESEL MAN ADJ) to see if that improves the response. If manually or auto peaking the preselector causes the amplitude response to be normal again, you might just need to perform the preselector adjustment and frequency response adjustment as described in the service manual.
Regards -