I goofed, looks like I've blown the low band mixer in my 8596E. A couple of questions:

There's a quite a few dual mixers to be had in the same housing but with different part numbers. Does anyone know to what extent they are interchangeable?

Looking at stuff online, the mixer appears to be a simple shunt diode. It's only 2.9GHz max. and there's loads of diodes readily available which can easily work up to that. I can't believe the beam lead package is essential and package sizes of 1.6mm (.06") or smaller are commonplace. BAT2402 comes in at 0.6mm (.023") which might be a challenge to handle. Anyone got any experience of using an alternative part for the mixer?

Anyone got a 5086-7952 to sell?

Thanks

Steve

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Hello,

not commercially affiliated. But Helmut Singer is going out of business...Id shoot them an email, and be like *fart*.

And see what happens...they are said to sit on tons of shit...

Thanks Jos, Tam. I contacted Singer, they don't have anything and also Luis, who can do the repair. He fixed a dead YIG oscillator for me a few years ago.

Steve

A postcript to this. Turns out I didn't kill the mixer but, as part of a plan to keep the analyser going while the original went away for repair, I bought a cheap mixer with blown low band.

The diode was shorted - a common result reported by others. The dead diode came off easily with a flick of a scalpel blade. I installed a Skyworks SMS7630-079LF as replacement (cathode to ground), fixing it in place with dabs of silver conductive paint (Electrolube SCP). This dries to form a reasonably secure connection, I planned to add a bit of epoxy for permanence.

It works! I haven't tested exhaustively as I realised the mixer wasn't the problem (see my other post re SYTF), but feeding signals directly to the low band input, the frequency response looks flat 10MHz - 1.8GHz and I've no reason to think it won't be fine over the full band 0 range.

Cost - ?2 for 5x diodes and ?10 for the SCP (both from Farnell). Got to be worth a try if you have a dead mixer and limited funds. Also, it doesn't mean you can't get a 'proper' repair later, the dried paint washes off with acetone to leave a clean surface for bonding.

If you do try it, be careful with the amount of paint; it can wick under the body of the diode and short it out.

Steve