music, guitars & other obsessions


Shanghai XinJian Instrument & Equipment Co.


While doing research on the QT-2 curve tracer, I found some interesting tidbits on the factory that made these test gear (and many more).

Originally founded as the Shanghai No. 21 Radio Factory in 1951 by the Shanghai Municipal Governement, Shanghai XinJian Instrument & Equipment Co. (“SHXJ”), became known nationally with its successful development the GT-1 Tube Characteristic Curve Tracer in June 1960, the tracer was capable of measuring the dynamic parameters of vacuum tubes. Mass production began in 1962. [Never seen one in existence yet…]

In 1962, SHXJ launched the GS-5 Tube Parameter Tester, mass production began in September 1966. The tester made use of different punch card to measure the static parameters of many different types of vacuum tubes, both foreign and domestic made. The measurement error was ± 5%. From 1962 to 1990, a total of 34,292 units were produced. [The GS-5 is a direct copy of the LS3-3.]

The early 1960s, the development of semiconductor parameter measurement was in demand. In 1962, the SHXJ began development of an experimental prototype transistor parameter measurement instrument. In 1963, JZC-1 (630-type) Transistor Tester began its production run. Thereafter, the transistor parameter measurement instrument categories expanded rapidly to form the QC and QG series in the early 1970s. These products can measure the cutoff frequency of the small power transistor, including noise figure, power gain, automatic gain control characteristics, etc., but are also capable of measuring the FET’s transconductance, pinch-off voltage, the drain saturation current, the input capacitance, the feedback capacitance and other parameters. The units are capable of measurement frequency range from the low-frequency, high-frequency, UHF, to the microwave band. The JS-7-type transistor parameter tester sales, with an annual output of 18,507 units, accounting for more than half of the total production the entire semiconductor measuring instrument production.

In 1962, SHXJ began development of a dynamic transistor curve tracer. And in 1963, the JT-1 Transistor Characteristics Curve Tracer was put into production. The instrument was not only able of observing the dynamic responses of the transistor under the different conditions, but was also capable of observing the base source voltage for reliable, quantitative and rapid measurements under dynamic operating conditions. By 1978, SHXJ also introduced higher power transistor curve tracers. These products were popular from the mid-1970s to the 1980’s [and some are still in production today such as the QT-2.]

SHXJ also tried to develop testers for solid-state circuits and CRT color picture tubes. In 1970, it released the 905 Solid State Circuit Analyzer, however, the sales were too small, and only a small batch was produced, the production was discontinued after two years. In 1976, SHXJ did produce a color picture tube tester, but only 7 units were made.

Another important product category for SHXJ was the noise tester noise measurement device with the growing domestic demand from the aerospace, communications, radar, and other industries in the 1970s. The noise measurement of high-frequency transistors placed high demand on the proposed noise the coefficient magnitude unified requirements. 1978, SHXJ launch the XO11 Coaxial Thermal Noise Measurement Standard Device, with output stability of 0.003 db, resolution of 0.01 dB, the noise generator can be precisely and continuously adjustable in 0.003 dB increments, was a high-stability, high sensitivity, high precision, high-resolution instruments that compared favorably to international standard in 1979. Saturation diode noise source development began in 1982 and mass production began in 1984, the Q03 Transistor Noise Standard Generator was used by the national standardization board.

By the end of 1990, SHXJ produced 23 types of measurement instruments, with annual production volume of 1819 units

Prizes and Awards.

1964 – Ministry of Machinery Industry New Product Award , Fourth Prize for the GT-2 Tube Characteristics Curve Tracer [which is the direct copy of the venerable Tektronix 570].
1979 – National Metrology Scientific Research Center, Third Prize – XO11 Coaxial Thermal Noise Measurement Device.
1979 – Ministry of Machinery Industry New Product Award, First Prize for JT-1 Transistor Characteristics Curve Tracer [which is the copy of the Tektronix 575].
1980 – Major Scientific Research by Shanghai Factories Shanghai Government., First Prize.
1983 – Ministry of Electronics Industry, High Quality Product for JS-7B Transistor Parameters Tester.
1988 – Ministry of Machinery Industry National Quality Award, Silver Medal for the the XJ4810 Transistor Characteristics Curve Tracer.

Some classic products made by the company:

This slideshow requires JavaScript.

Water Disaster Again

My house seems to be possessed by some sort of water demon! Since we moved in, we have experienced numerous leaks, floods on every single floor of this 4-story townhouse, it is just un-believable! The latest leak started four days ago, after non-stop two day rain. We discovered that the roof deck had a leak around the ventilation pipes which were supposedly sealed just a few years ago when a similar leak occurred. Fudge…

After we repaired the leak, all was fine for a day, then the rain started again, this time, the water started to drip down from the electrical wires right into the electrical panel on the second as well as the basement – the water simply followed the wires down through the cracks in the wire as far as we can tell, our neighbor also suffered the same problem, so we suspect that there must be an unplugged hole (or holes) somewhere in the adjointing wall that we share. More repair will be done this weekend.

So far, all the walls on the front of the building have been soaked, they are soggy and need to be scraped off and repainted. There is significant damage done to Gaby’s wall cabinets, perhaps we will just rip them down and toss them out…

The electrical shorts burned out several power adapters and circuit breakers, and an Apple Macbook which was submerged in a puddle of water – just being at the wrong place at the wrong time… The repair bill came out to over RMB700 alone.

Have you ever seen sparks flying off the breakers because water was pouring right into the wire contacts?! Sparks, smoke followed by a burning smell, it is not a pretty sight.

Could not wait for all this ordeal to be over soon ;-(


Where My Damn Tools At?

While I managed to build the Fender kit and Fat Booster/Bastard without much difficulty, after going through the various DIY sites, it is pretty clear that I need more tools! The selection of tools available to the hobbyist is quite daunting, one can easily spend thousand Dollars not Yuan on these things. Of course, it is possible to do the job with your everyday handyman tools, which I already have, but to get decent results from them, one need to be very creative and/or very good with tools, which I am not, so the solution is to get “professional quality” tools to compensate for my own shortcomings.

Aside from the typical small tools like – table vice, metal/wood files, tweezers, center punch, metal shear, step drill bits, etc. I found that to fabricate PCBs and cutting holes in chassis, I really should have both a drill press and a high speed cutter/grinder a la Dremel tool, then there is whole business of drilling PCB holes, which I never knew required very high speed drill speed (60,000-over 100,000 rpm!)

Please bear in mind that people have done PCBs for years with nothing but Drumel tools, or even power/portable hand drills, so it can definitely be done. But these options just do not seem like the right way to me… I am definitely not going to attempt drilling holes in the PCBs free hand style… At the other end of the spectrum is a mini CNC machine, which has dropped in price over the years, and many are available for around 2,000-5000 yuan (~$350-800), which is well within the reach of the hobbyist, but there seems to be a pretty steep learning curve with all the CAD. CNC control software involved, so it may be worth a look in the future but not now. If I can find a shop that not only sells the CNC machines, but can also provide training and support, I will definitely get one, since not only I can eliminate the need for heat or UV image transfers to the PCBs, chemical etching (the worst part), manual hole drilling, it can also mill the elaborate designs for the stompboxes directly. The whole idea just really appeals to me.

Anyway, back to reality, I decided for now, just get the following:

1) a bench drill press (13mm),
2) high speed jewler drill/polish set and
3) drill press adapter for the high speed drill.

All three will cost me only about 500 yuan, so why not. I will also order some Tungsten Carbide drill bits to try them with the high speed drill, since the max rotation speed is only 30,000 rpm, these bits may or may not work (I have seen posts on both online), anyway they are cheap enough, so it is worth a try.

Here is the drill press that I plan to order (280 yuan or $43), it is darn cheap and has good specs, hopefully it won’t be a POS like many things Made In China.

Here is the high speed drill press adapter (70 yuan or $11), it looks pretty cheap, hope it doesn’t tip over when I work… But it looks like the Drumel drill press stand that I saw online.

Here is the high speed drill kit (76 yuan or $12), the max rotation speed is 30,000 rpm. It can be used with metal blades to cut PCBs as well. Of course, grinding and polishing the stompboxes, I think this should come in very handy.

So much for my planning, I ended up getting just a small table top drill press, and it works pretty well on the skinny metal, have not tried to drill the stompboxes with it yet, but aluminum is pretty soft, so hopefully it won’t be a problem…

Building A Parts Inventory – The Zen of Taobao

As I gear up for my amp and pedal board builds, the first task was to build up a parts inventory, well it turned out not so easy – in China, there is no Digi-key, Antique Radio Supplies, Angela Instrument, Mojo Amps, etc. to meet the demand of the DIY market, I am so jealous of the people in the US, who can just go to a few solid sources and get all the parts, here I had to resort to order from multiple vendors via Taobao over several weeks of searching – thus the name of this post.

First, I must say that Taobao is quite impressive, you can source almost anything through it, its root with Alibaba is clearly apparent, it is The Place to hawk your wares in China, even office workers, students have open stores on Taobao. Where is your Taobao store?!Overall, I think Taobao is even better than eBay, but then again I have not used eBay for quite sometime, so who knows… Unlike eBay, the site is not auction driven, so everything is available for “Buy It Now”. But like most of the Chinese websites, the Taobao site is tacky and hard to look at, the site is too busy and chaotic to the eyes of a “western eye” like me, may be I lived in the States for too long but I really can not stand the look and feel of the typical Chinese websites, I think there is definitely a culture reason to explain why that is so… Any, back to the topic at hand.

Anyway, it took me two solid weeks of Taobao-ing to gather the parts, some came easily, but some were surprisingly hard to track down, in nay event, I manged to get 90% of the parts that I needed, so some modifications to the designs will have to be made later, it could get interesting, being the lazy person that I am, I really just wanted to get all the parts as specified, but that is not to be…

The Zen of Taobao – be patient and use the search engine wisely, while I tried my best in translating everything from English to Chinese for the parts, but not knowing the actual or proper names of them in Chinese was frustrating, since electric parts are not common everyday terms that people use, I can’t just ask someone “how do you say xyz in Chinese”, so the process to determine the proper names for the parts turned to to be rather time-consuming and tedious…

Typically when you do a search on Taobao, hundreds of matching parts will pop up, or the opposite happens, either way, lots of fine-tuning in the search terms were needed, you will also see some vendors purposely put multiple parts under the same category or worse, just fraudsters low-balling the price to get traffic to their stores, so the first thing to do is to weed out those “fillers” and drill down to some real vendors with actual items of interest.

Once you get to the store, it will still take sometime to get the exact item that you want, but because all the vendors are using the same Taobao storefront engine, one can usually navigate through the store with ease, but I must warn you that it is very easy to get side-tracked – many foolish items were ordered because of this, even though I tried my hardest not to be temped by the “shop window”, I still ended up with a bunch of parts that I probably don’t really need.

Anyway, before you get to the shopping cart, you need to double-check the inventory with the vendor, usually via Alibaobao or QQ. Make sure that they have the parts in stock before you hit the check out button – you can of course cancel or change the order later, but it takes a bit of extra work, so best to just ask and make sure… As it is often the case, you will need to get the vendor to adjust the shipping rate, as a majority of them do not bother to use the Taobao program properly to group the orders together and figure out the proper shipping rate, instead you get charged for every single item that you order so it is possible to get a shipping rate larger than your actual order, really!? Why can’t shopkeepers spend sometime getting that basic thing right?!

For small orders, and there were many – I had to source some of the parts locally at Cai Ge Electronic Market, which is a topic for another day. The unit price there are usually 25-100% higher than those shown on Taobao, WTF, you say. For electronic parts, especially passive parts, it is quite common for the vendor to establish a minimum order like 100 or 1000 pieces, you can of course find vendors that are willing to sell a piece or two to you, but be prepare to pay top yuan for such orders. Every time I shop at Cai Ge, I felt like I was ripped off, because when the vendors know that you are just a hobbyist (your small order gives it away) – a small fry, they really have little incentive to treat you fairly, it is “get as much you can while you can” with them, bastards!

It turned out that sourcing components for the tube amps was relatively easy, first of all, the part count are much smaller than the pedal boxes and because there are many specialists that cater to the burgeoning tube DIY market in China, it makes ordering parts a pretty simple process. I will do a post on some of those stores later.

While it was relatively easy to source the parts for the tube amps, I still wasted a lot of time and wasted energy because I could not make up my mind to turret boards, epoxy boards with through holes, or just point-to-point? Each method requires its own special parts which take time to track down. In addition, like the cheap bastard that I am, I just wasn’t about to fork out top yuan to get the audiophile-quality parts, which were all readily available, so I have no one to blame in this case. I saved money but at what cost?! Even with my cheap-ass way of parts selection, I think out of everything, a surprising 20% may be even more were spent on the stupid hardware, i.e., the parts that do not even make any damn sound at all! Let’s not even get into whole issue with the chassis now, that is another can of worms, and will discussed in due course later.

But getting the parts for the pedals was another story altogether. Man! I really did not think it would be this difficult, for example, just for the transistors, I had to order them from half a dozen stores and I am still short of a couple of them… It was also difficult to track down a common part like the potentiometer, unless of course if you want to pay more than 8 yuan for one cheap carbon comp pot! May be I am just being too cheap as usual…

Even though a single pedal may just contain a few parts, given the large number of pedals that I want to try out (I set my sights high ;-), I still had to order a lot of parts, especially the transistors, resistors and capacitors, some of which turned out may be obsolete or very hard to get, especially with some of the older designs. Many a time, I thought for all the yuan I was spending, I could have bought all the pedals I ever need, why do I put up with all this bull shit?But then I think what is the fun in that? Did I not start this whole project with the intention to try out different pedal designs, and to learn/refresh my basic electronic knowledge which is unfortunately woefully lacking these days…

There are many takeaways from this saga so far, first, proper planning is a must, or as they say “measure twice, cut once”. Since there are so many plans available for the amp and pedal build, I probably bit off a bit more than I can chew by try to build so many different ones all at once, this may be partly justified by the fact that it is very inefficient to order parts in small quantity, if I do that I might as well just buy the finished amp or pedal, as there is not much difference in price after you factor in all the time, energy that goes into an exercise like this… I guess we will see if my “efficiency theory” will work out or not.

I did a quick calculation, so far, I have “invested” close to 10,000 yuan in the parts, some were no doubt impulse purchases, I mean do I really need to have hundreds of knobs, am I really going to use them all? How many pedals can I build or use?! But in the heat of reading, AX84, SEWatt, etc. it was very easy to got carried away and start ordering parts like a mad man, oh well, there is always the Salvation Army to haul my junk away later.

With the last of the parts coming in the next few days, I am finally ready to bread-board some amps and pedals, I am also relieved not to be spending hours and hours going through Taobao, looking for those damn parts, my eyes really could use a break!

Another side note, my experiences with the orders have been just great so far, most of the orders were delivered within two days, even on weekends. I didn’t have a single order screwed up because of the delivery company. Another finding was that, most of the orders were carefully packed, labeled, and stuffed into the boxes for shipping, good job I say!

This post is really getting too long, be back with more later…

Nice New Building in Tienjin

Can we please get some decent design buildings in Shanghai?

Paul Merton In China

Hope to see this soon via bittorrent…