WHERE CAN I PURCHASE THESE??

[Shadetree Mechanic]

Is this x-bones that some of us bought the variable power boards from?

I believe so, he has a listing for that too.

 

[David Eden]

Rf

 

[David Eden]

Rf parts has those I believe

 

[David Eden]

Why don't you just make the boards yourself . It's actually quite easy . Especially something that simple. You can buy the board on eBay and you can use muratic acid to do the etching or you can buy the regular chemical for etching . But if you want them to look professional you need a laser printer and some transparency sheets you can buy almost anywhere , you use which ever program on your PC. Then you layout the board . Set your printer for the darkest setting then print to the transparency. Then use some alcohol clean the copper board really good , then get your clothes iron and put something between your iron and the transparency turn the iron hi position it on the board iron it and the toner will transfer to the copper. If there are any spots not covered real good you can use your sharpie permanent marker to fill the thin spots. With muratic acid you need to add some good peroxide to the acid it speeds it up. And submerge the board and watch the exposed copper vanish . Then once it's all gone rinse it with clean water . Then use some nail polish remover to take the toner off and you have a circuit board g

 

[brandon7861]

With muratic acid you need to add some good peroxide to the acid it speeds it up. And submerge the board and watch the exposed copper vanish .

A good variation of that is to use an aquarium bubbler instead of hydrogen peroxide, but it takes a day or two to prepare for the first time. But once you have it, it lasts forever. When the mixture becomes dark from use, just bubble more air through it until it becomes transparent green again. This way, the water in the peroxide is not diluting the solution down and you can repeatedly reuse it (it gets stronger and stronger instead of more watered down). I have been using the same captain morgan bottle of it for 7 years and have yet to add more muriatic acid to it, just air. Eventually, it may need more acid, but it takes a very long time. Just don't use an aquarium stone. As tempting as it is, they dissolve in the acid, lol. Just use a rubber hose and a cotton ball to keep it from splashing out from bubbling action. To however much muriatic you initially use, add enough copper to consume about half of it and bubble air through it until the copper is gone and the solution is transparent green. You don't want to add so much copper initially that the copper chloride precipitates out leaving no muriatic for reactivating later..

A quick diy etchant is vinegar, 3% hydrogen peroxide and table salt. It's just a little slower. The salt reacts with the vinegar to produce hydrochloric acid in situ (weaker version of muriatic). I never get tired of the copper surface exploding with bubbles when the salt settles on the copper.

Copper chloride is mildly toxic to humans and extremely toxic to aquatic life. If you decide you want to destroy it, just add aluminum foil. It will precipitate out the copper. Using my method above, you should never need to do that unless you make lots of it. The vinegar method also produces copper chloride, and it should be treated the same way, but I'm not the EPA lol. I do it because I don't want it in our well water, but most people simply flush it.

 

[Onelasttime]

Modification MRF477 -> MRF455

Good Image and a little bit of information for those wanting to make their own.


I would love to have an extra board since I have a 1998 President Lincoln with this board fromt he factory. Do we have a sorce? I do not have or use Facebook and have not for about 4 or 5 years.

Not long ago when the Chip-Switch was made available again this board was how I found out and how I gained contact information for the purchase. Been looking for a spare since about 2012.

 

[Onelasttime]

In fact even though my 1998 President Lincoln is going strong I picked up 3 high beta high gain MRF455's about 10-15 years ago with the idea of having some finals handy for my old girl. I also have a few NTE/ECG eqivalants since the MRF455 and the like are so common in little amps and such.

I wish I had stocked up on all the plain Jane stuff like 2SC1969's and 1701's and 2166's etc... I think I have 1 set of matched 2SC1969's and few Ele Flow knock offs. Hind sight being 20/20. So far I have not had to put a set of Mosfets in place of bipolars in a radio yet and I hope I never have to if it can be helped.

In a million years I never dreamed that bipolars would disapear and we would be left in an abyss of cheap garbage switching mosfets being used in RF circuits. I thought somone would eventualy come out with a quality dedicated durable RF Mosfet to replace transistors like the 2SC1969 and like.

 

[nomadradio]

That's what the RD16HHF1 is supposed to be. Mitsubishi's answer for the discontinued bipolar.

Nice try.

73

 

[brandon7861]

Dremel a blank PCB to fit and use acrylic fingernail paint to mask off the traces for etching. Its a simple design, so free-handing a few with a paint brush should be easy enough. There is no need for a fancy toner/dryfilm/UV etc procedure. Paint on the traces, let dry, etch in vinegar/peroxide/salt, then remove the fingernail paint with acetone after etching. That was my main method before getting UV film.