Bias Diode Boards

[brandon7861]

My last post about this got quickly deleted when china emailed me stating they would have to charge me more for my parts. Apparently 12x8mm is too small for them and making them individual pieces was a bad idea. I tried to redo the parts using panelization, and probably screwed it up, but we will see.

They emailed me this time as well stating the V cuts would be difficult and that they needed more money for this version too, but at least it was not as expensive as my last attempt. If I run into problems again, I will have to hire someone that knows what they are doing to make me a gerber file. Hopefully then snap apart cleanly.

 

[brandon7861]

I ran this idea past chatgpt and it suggested the diode be slightly proud ( slightly past the surface of the board) to ensure the diode body presses against the heat sync and that I should use minimal solder to limit thermal mass so it tracks faster. As for how far the diode sticks out past the board, we decided on the thickness of a paper grocery bag.

I didn't even think of those two things so I am very happy I decided to sanity check the plan.

 

[nomadradio]

The original part was built on a very-thin copper laminate. Odds are the diode will track the temperature of the heat-sink surface rapidly enough.

73

 

[brandon7861]

I don't know how thick the copper is that they are putting on the board, but I had the cheapest option selected. 1 ounce. Not sure if thats finished or just the base layer, but I suspect it will be around 35um thick.

I also went with 0.8mm thickness boards rather than 1.6mm so the diode legs do not go into the cutout. I figured that problem out while trying to put one of my surface mount 4148's in a thicker board I cut last weekend. The diode legs got lost in the hole and soldering them required bridging the gap. That shouldn't be an issue with the thinner boards.

I am going to test these in my washington and compare them to the originals and post the video of the results on youtube. Hopefully they are a good match. Production is at 53% and mouser just printed the label so it will still be a week or so before I can test them.

 

[brandon7861]

Maybe you guys could help me out with something. Assuming these work as intended, I will need to make a fleabay ad. I know the 148 and the washington used these, but if I had a list of all the radios that used the MV1Y and MV13YH diodes, I could add them to the description. If you know of radios besides the washington and 148/2000 that used these, I would appreciate knowing which ones.

Thanks!!

 

[nomadradio]

Now there's a list. I'll see what I can come up with.

73

 

[brandon7861]

I suppose if there are that many radios that use it, I can just use the MV1Y and MV13YH in the description. Don't go out of your way doing this if its a big job.

 

[nomadradio]

Well, yeah. It's a long list. I'd guess the MV type numbers would serve to identify them just fine. This type series diode array appeared in a great many stereo amplifiers from the 70s/80s/90s. They were molded inside plastic with a slot at one end for a mount screw. I'll see if I can find some part numbers for those. Can't remember the part numbers, but there's a good chance we still have some in the inventory from those days. There's a trend to restoring those speaker amplifiers these days. Might be an additional market. I'll have a look at the stock for part numbers. They were made with two three, or even four diodes to bias complementary-symmetry speaker amps.

73

 

[brandon7861]

Thanks Nomad! I sure appreciate it!

Now I am regretting not getting the 4-diode version with 6 legs. I could have used them the same way, and they would have had more surface area for the heat sync.
If I ever burn through the 500 pieces I ordered, I will increase the hole size in the board and get the bigger diode arrays.

 

[brandon7861]

Boards arrived and I was very happy with the V-cut. They snap apart nice and clean and the diodes fit nicely. I am hoping to get them tested Wednesday.

 

[Cable Guy]

Boards arrived and I was very happy with the V-cut. They snap apart nice and clean and the diodes fit nicely. I am hoping to get them tested Wednesday.
View attachment 76652View attachment 76653
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Great job, that's a thing of beauty, and if they work well I want to buy a few dozen for sure.

 

[nomadradio]

Rock on! Those look excellent! Gotta master the art of the v-cut. Looks easier than my sheet-metal shear.

73

 

[brandon7861]

Rock on! Those look excellent! Gotta master the art of the v-cut. Looks easier than my sheet-metal shear.

73

Thanks!

In easyEDA, if you want to make many copies of one part on a big board, get one piece's layers finished, select everything, then go to tools>panellize and in there it will let you pick V-cut or stamp hole (or both) along with how many rows and columns (quantity).