Tag Archives: YTF

HP 8566B Spectrum Analyzer: 2 partial units and some spare parts

This story starts with a set of rather valuable 8566B parts that I received for free a litte while ago:
8566b spare parts

A partial unit, stripped of of most of its RF parts, and missing some boards, and missing the OCXO.
8566b partial unit1

For a long time, I have been looking for another partial unit that can provide the missing boards, the OCXO, and some bits of hardware to complete the instrument. Not worried about the 85662A display units, because I have a perfectly working spare unit around, or could use the unit of the 8568B.
Finally, a unit showed up, also missing some boards and parts, but luckily, not the boards that I needed -except, also no attenuator, and no OCXO here.
8566b partial unit 2
8566b partial unit2

That’s the start, the empty space that is going to hold the RF treasures:
8566b empty space

The YTO assy, missing the YTO, and other bits.
8566b yto loop incomplete

This part, the 5086-7226, to do it fully justice, one would have to talk about it for a few hours. It is a not only gold plated inside and out, but HP used two kinds of solds, of different melting point, to assemble the inner workings in subsequent steps, without melting the already assembled parts….
8566b 5086-7226 YTF

Some more pictures – the YTF driver.
8566b ytf driver front
8566b yig driver back

The 1st and 2nd converter assy, ready for the semi rigid lines to be attached.
8566b 1st and 2nd converter

A high quality input relais and a band pass filter.
8566b input relais and bp filter

Well, unfortunatly, don’t have a spare 8566B/8568B OCXO around, and they go on xbay for no less then USD 50, often, no less then USD 100, that’s ridiculous.
May this unit, which is very low phase noise, very stable, from a HP 3585A analyzer, can be made fit? Ovenaire OSC 73-52.
8566b spare ocxo 0960-0465 ovenaire osc 73-52 10 mhz

After a LOT of fiddly work:
8568b assembly progress

8568b testing

A first signal!! Amazing! Frequency is off by 80/300 MHz – the unit will need a proper alignment, but the PLLs are all locked, which is a great start.
8566b a signal

And, the noise – the effect of harmonic mixing can be clearly seen, so the input stage and mixers seem to be all working!
8566b noise

More to come!