JE990 Lives!

Not to rain on the parade, but on the Fair-rite issue, here's a bit of correspondence I had with them a little over a year ago:

>>I'm interested in an older shield bead that was Fair-rite part number 2673225111. Is that part still available, or is a comparable part still being made?

I don't recall exactly where I got that part number, but I'm pretty sure it was either from the 990 patent or possibly from a very old copy of the 990 paper that I have (I can probably find my source on that if anyone is interested).

The reply from Fair-rite:

>>The closest replacement part would be P/N 2673666611 - but this is non-standard and typically requires a $ 1000.00 minimum order.

At the time I was already coming to the conclusion that DIY for the 990 is barely cost-effective, even if you don't care about the cost of your time, expecially when I found some of the threads CJ mentioned and discovered that the JH990 is only about $50. Personally, I decided to save my limited DIY time for items without a readily available, inexpensive, and very high quality version already on the market. . .

The original paper by Deane says Fair-Rite 2673225111; IIRC I have seen a ferrite bead manufactured by Schaffner that seems to fit the application perfectly.

Samuel

At the time I was already coming to the conclusion that DIY for the 990 is barely cost-effective...

Click to expand...

You're right. But then, I don't DIY for cost-effectiveness. Ask my wife!

I still need to make the ground plane, so the board won't be finished until my next bout of insomnia.

There must have been someone working at one of the electronics stores here who was interested in the 990 too or else why would they carry six-hole ferrite beads? Do they have another common use? Baluns for RF?

My home-etch...just so you know I haven't dropped this - just waiting on parts. Got inspired by Samuel's dead copper thread and decided to do a ground plane on both sides not for any particular reason than I thought it looked good.

Bad news on the locally-available inductor core - I wound it as I thought it should be wound from the description in the AES paper. It didn't measure correctly. I've done a more conventional wind and will give it a try but it's pretty clear that the material isn't the right stuff. I tried looking around the Schaffner site but didn't find anything - got a link? Anyway, the dimensions are exactly right so my layout should accomodate the correct part (if we can find it).

Cool!!!!!!!!!!!!!!!!!!!!!!!!!!

:guinness:
Fabio

Ok, got most of the parts in yesterday. I tested the newly wound inductor but it only looks like 8uH :sad: Anyway, I'll stuff the rest of the parts and see if I haven't made any mistakes. If it all looks ok, I'll post the gerbers. I did a search and it looks like omeiko built one of the dale116dot7 ones, but just left out the inductors. Has anyone built it using and testing with a different inductor - something easier to find maybe?

I looked up the part no. for the inductor I had in my mind, it is:
Schaffner, 2943777741

This is the ferrite bead with the highest impedance I've found so far. No known source yet, unfortunately.

Samuel

dims?
Al number?
mH required?

The original core is a little under 1/4" and 3/8" long with six holes. AWG 30 wire passes through the holes making a single pass through each one. The value should be 0.02mH. Check the other thread.

OK.
2503's collecting dust.
Need address for 1176 compensatory factor.


0.02 Mh is only 20 uH, you sure about that number?

I have core here, 0.2 by 7/16 in.

7 turns gives 500 uH.
2 turns = 35 uH.
1 turn = 11 uH
Probably of no use.

Damn, you must have some spam filtering going on - sent you my addy ages ago. I'll do it again from Hotmail.

Yeah, 20uH but since you asked for mH I thought I'd state it that way. Remember that they aren't full turns - they get threaded in a funny sort of way - wonder if you can do this:

Just checked and I deleted your email addy - send again via PM...or just check your PMs!

got addy, stuff gone tomorrow

Yes, they make 6 small cores out of single core, but it is still 6 turns.
Keep looking. Tons of beads out there.

Bad to the bbbbbbbbbone, dude!

Yes, they make 6 small cores out of single core, but it is still 6 turns.
Keep looking. Tons of beads out there.

Click to expand...

Thanks CJ. I think I was posting while you were still winding and only saw the 500uH figure. And I forgot that you inductor guys call a wire going through a core one "turn" - there was an argument that lasted a few months over that point in our local electronics magazine.

Have you got an idea of what the permeability is of the core you tested?

Hey guys, when wiring such a small ferrite, is it important to put a kind of isolating varnish on the wire?

I haven't found that necessary - I used magnet wire.
You DO need to put an insulator around the ferrite if it can contact the metal transistor case, such as heat shrink.

dmp said:

I haven't found that necessary - I used magnet wire.
You DO need to put an insulator around the ferrite if it can contact the metal transistor case, such as heat shrink.

Click to expand...

Magnet wire is isolated right?
Which thickness?