Electronics > Repair
E4407B Tracking Generator Repair
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analogRF:

--- Quote from: KE5FX on September 25, 2020, 11:26:48 pm ---That looks like a big inductor, usually something you'd see in an HP switching supply.  0410-2110 is the HP part #.  Odd that it has polarity markings, though.

--- End quote ---

that's why it is not an inductor. and it has 4 terminals by the way not three, two of them go to ground.

it should be easy to trace the pins and see where they are connected to and where the supply lines are
smgvbest:
Oh. I missed that center one.  Thanks for pointing that out
suj:
The element marked LF3 is probably 850 MHz LPF from Mini-Circuits (LFTC-850). One of the possibilities is then to multiplicate x6 frequency behind the LPF (maybe x2 + x3 - is the black element in front of the interdigital filter a diode?). If we assume that the MC ADE-2ASK mixer has a maximum frequency 1 GHz, the BPF should be 653.56 MHz (if the multiplication is x6). Then this signal would be created by mixing 600 MHz and a free-running (!!!) 53.56 MHz oscillator. If the multiplication behind LF3 is x7 (rather cumbersome), the BPF is 560.2 MHz and the oscillator is 39.8 MHz. Strange...
analogRF:
Sandra, can you post close up pictures of the designated components in this photo? their markings are not readable
analogRF:
the RLC Elec. filter P/N 9135-0389 is a 783MHz bandpass filter. 784 x 5=3.92GHz  :-+
so there must be a multiplication by 5 (picking up 5th harmonic) before reaching the main golden mixer


however, the mystery remains how this frequency is locked if at all. In all low frequency TGs that I have repaired before (HP and Anritsu and Advantest) there is always a VCO generating a fixed frequency which is the start frequency of LO and it is always locked to a stable reference.


i was thinking that maybe they used that ADE-2 mixer as a phase detector (hard driving of RF and LO ports) but with above information, it is not possible....
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