Tag Archives: 4352b

Agilent 4352B VCO/PLL Signal Analyzer: working!

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.

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

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.