Tag Archives: 4352b

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Agilent 4352B VCO/PLL Signal Analyzer: see you again, after 5 years

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After some years, again on the bench, a trusty 4352B VCO/PLL Signal Analyzer. A rather specialized instrument, but hard to replace with any more recent instrument, unless you are shopping in the 50 kEUR+ category.

he earlier repair: Agilent 4352B VCO/PLL Signal Analyzer: working! – I left a mark inside the cover, as I typically do after performing significant repairs.

Over time, the display has aged and unfortunately became unreadable. Not a big issue, because there is a connector for an external monitor, but still not very practical to use.

The polarizer can be pulled off, but the glue stinks and is very sticky, would be a big effort to do a polarizer repair.

The LCD, a Sharp LQ9D340H is still available, but the cost is high, even when sourcing from China, about 200 EUR a piece. Note: don’t mix up the LQ9D340 with the LQ9D340H – these are not necessarily compatible according to the datasheets.

After some study, I found a good offer for a used LQ084V1DG21 8.4″ 640×480 Sharp LCD panel. These are compatible with the 340H.

Offer of a German IT used parts seller:

The used panel had a special adapter – not compatible with the Agilent flat ribbon adapter of the 4352B – removed the screw and the adapter with no problem at all.

The installation went without any trouble.

The new LQ084 is a little thicker than the 340H, but it all fits into the LCD compartment.

The backlight driver and even the backlight cable position are compatible – just needed to plug the new LCD in.

Finally, not too much to do further – close the case, insert the screws, a quick test run.

Flawlessly working – starting up like before – and, I didn’t even have to remove the inner cover or any boards – just the front panel and LCD compartment.

Various

Agilent 4352B VCO/PLL Signal Analyzer: working!

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After a short xmas vacation, several spare parts arrived, including, 10 amp solder-in fuses, and thermal glue (704 silicon glue).

The glue is needed to mount the defective/blown thermal fuse to the power resistor. This resistor usually stays cool but will heat up in case of a power supply failure.

The fuse protects the primary of the switchmode transformer, it is a 10 Amp fuse, and it took a while to find it – it is located in a hidden place underneath the transformer.

Now, with the fuse installed, the thermal fuse glued to the resistor, and the two drive mostfets replaced, the Artsyn 24 Volts supply is starting up just fine. All self-tests passed!

Next step, let’s update the firmware, and do some tests.

The firmware version 2.11 is the latest one available, but it needs to be loaded from a 3.5 inch floppy – I have a USB floppy drive here, and one single disc which I purchased from Sri Lanka. Took a few attempts to convince the 4352B to read the disc and load the firmware. But finally, success!

Many tests could be done, here just a simple test with a 15 MHz signal from a 3585A vs. a 8642B generator. Seems to work well, and easy to use.

Now we can close the case, and use the device for VCO characterization, phase noise measurement, etc.

General

Agilent 4352B VCO/PLL Signal Analyzer: a great find (hopefully!)

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I found a great deal on a “totally faulty” 4352B, well, it is a bit a cat in a sack, as we say in Germany, you never know what you get. It shipped from Manila, even better! List price, I think it was close to USD 50k!

It’s a clean unit, except for about 100 stickers and seals!

All heavily shielded, many kinds of screws and metal plates to keep to good waves in, and the bad waves out.

The brain of the machine – quite sophisticated – Japanese engineering (this unit has been manufactured by HP Japan!).

After some study and test, it is clear, it is dead because there just isn’t any power. The power supply is a two-stage supply, first stage, a switchmode universal voltage to 24 Volt (190 Watt) supply, bz maker Artesyn, then a really top quality 2nd stage, made by Agilent. And guess what, the 24 Volt supply is faultly!

This supply uses power factor correction, and two IRFBE30 MOSFETs to drive the transformer – one of them is shorted shot. Otherwise, no damage to be found on the board so far, except the thermal fuse, which must have cut out immediately (even the primary fuse is OK – so there is hope that this will be an easy repair of the 24 V supply).

Ordered some spare thermal fuses and MOSFETs, quite common IRFBE30 type – low cost. Let’s see if this will let us get the power back, if not, worst case, we can always install a new 24 V 200 W supply – there is enough space in the case.

In any case, these VCO analyzers are a great deal – there is a 26.5 GHz (!! APC 3.5 !!) power splitter inside, value, still available today, EUR 1350, and a 13 GHz detector, value, 450 EUR. But let’s keep fingers crossed that this won’t become a parts unit anytime soon.