I recently took apart an old spectrum analyzer Advantest R4131D.

xy598646744

I recently took apart an old spectrum analyzer Advantest R4131D. [Copy link]

 

 

I recently got an old spectrum analyzer Advantest R4131D. The frequency is accurate, but the power is inaccurate. I disassembled it to see if there is any hope of repairing it. For the convenience of debugging, I installed the power board and digital board. I didn't take a photo.

okhxyyo

Ha, waiting to see the OP share the repair situation~~ I hope it can be repaired~~

dcexpert

The board has a history, and some chips may have been discontinued.

xy598646744

dcexpert posted on 2020-6-10 08:54 The board has a history, and some chips may have been discontinued.

As a product of 1988, it is still of reference value.

xy598646744

okhxyyo posted on 2020-6-10 07:57 Ha, waiting to see the OP share the repair status~~ Hope it can be fixed~~

You need a multimeter to fix this. If you have enough resources, you can get a spectrum analyzer. An oscilloscope can't help with the high-frequency part. The frequency is too high and the low-pass filter inside the oscilloscope filters it out. A multimeter directly measures the effective value of power.

wsmysyn

It is indeed very old. Advantest’s most powerful product now is ATE equipment. I wonder if they also make other instruments.

xy598646744

After a lot of hard work, the result was a fool. I was wrong to say that it was a cavity oscillator. Let me correct it. It was a dielectric oscillator. To be honest, I didn't even open the cover of that thing. After a lot of trouble (because I don't have a spectrum analyzer that can measure the high frequency part, I can only judge based on the multimeter, signal source, and oscilloscope, which is a bit troublesome). The preliminary judgment is that there is a problem with the frequency converter of 0736. The 30m local oscillator of the mixer mixes with the 26.4m to get a 3.5m signal. The output power is abnormal. I haven't verified it. It is estimated that it is likely to be a problem. There is no way to repair it now. This thing is antique and there is no place to buy components. Oh, it's very tangled.

宋元浩

xy598646744 posted on 2020-7-7 19:27 The operation was as fierce as a tiger, but the result was idiot. I said it was a cavity oscillator before, which was wrong. Let me correct it. It was a dielectric oscillator. To be honest, that's a joke...

It's a pity, but the host's disassembly is also worthy of praise

freebsder

How much did you charge?

xy598646744

freebsder posted on 2020-7-8 19:27 How much did you charge?

I bought it for 1,000 yuan, and the boss said there would be no dismantling or repairs. But when I got it back, I found that many places had been moved.

xy598646744

freebsder posted on 2020-7-8 19:27 How much did you charge?

My friend, you can buy a good one at this price. My suggestion: if you buy it, be sure to check it out, and don't just accept it because there is no connector.

xy598646744

I recently studied this mixer. This is a double-balanced mixer. The electrical schematic diagram of this mixer is as follows

Because this mixer requires a relatively high amplitude of the local oscillator (to ensure that the diode works in a switching state, i.e. nonlinear), I dismantled the original mixer and tested it, and found that the internal diode was scrapped. I am still trying to figure out how to save it. . .

wsmysyn

xy598646744 posted on 2020-7-11 11:38 I bought it for 1,000 yuan, and the boss said that he would not dismantle or repair it. But when I got it back, I found that many places had been moved.

Second-hand products are not to be trusted. If there is no reliable channel, it is a scam. Our former manager knew a second-hand instrument dealer. If they received a product with some defects or problems and could not be sold, they would send it directly to Guangdong for refurbishment and repair, and then sell it at a higher price. Most people may not be able to see the tricks inside. . . . .

freebsder

freebsder posted on 2020-7-8 19:27 How much did you charge?

1000 is not expensive, and it is not cheap to collect such a big thing, haha. Of course, collecting is something that only people who are "well fed" do.

xy598646744

I can only tinker with it occasionally after get off work, and the progress is always very slow. I can make a full-bridge flying lead with the ready-made Schottky, but I use SS34, and the reverse current of about 10ma is a bit large according to the manual, and the noise caused by the reverse current is also a bit large. If it is replaced with a higher performance one, it should be more perfect. I simply bought an ADE-1MH-4+ mixer online (second-hand disassembled machine, please note that the pins 2 and 3 of this model and ADE-1MH+ are reversed. I replaced the latter pins and the problem still exists, which made me doubt whether I made a wrong judgment), and directly replaced it with flying leads. There is no big problem after testing, and it is fixed with fine-tuning.

苯宝宝正辛酸

Just adjust the amptd cal on the instrument panel.

苯宝宝正辛酸

The potentiometer next to the power switch that you need to insert a screwdriver to adjust has the words "amptd cal" underneath it. That is for calibrating the signal amplitude.

苯宝宝正辛酸

It turned out to be the one who got scammed on the crystal radio forum.

wb8899

Does the host's machine come with a built-in signal source? What frequency and power does the built-in signal source have? I also want to buy one on Xianyu

xy598646744

wb8899 posted on 2020-8-7 22:32 Does the host's machine have its own signal source? What frequency and power does the built-in signal source have? I also want to buy one on Xianyu

This machine comes with a calibration source that can only output 200M -30db (that is, the intermediate frequency mixing local oscillator signal inside the machine).

Note: No signal source or tracking source is included.