On 3/4/2014 9:15 AM, wrote:
OK, at this point I am wondering just what kind of FETs to use for this thing. I'm sure y'all are alot more familiar with what kind of MOSFETS are out there than I am. Some of youse iz real injunears, I am just a half decent hack. As such I am not all that familiar with what is available.

Max limits are pretty obvious and not taxing. Just with some quick mental math I see Pd as being easy, maybe 3 W if that. Max Id is not even an ampere and Vds about 100 V. The problem is getting the frequency response. Even the gain should not be all that critical because there is a 1 K resistor from gate to drain. The problem is that offhand I just don't know of an otherwise suitable MOSFET for use up to 275 Mhz. Even a video output in a high end CRT monitor would not handle it I think.

Because of the massive level of feedback, maybe I could get away with a 100 or 150 Mhz device no ? I doubt it would be a good idea to go below 150 Mhz here, in fact I would like to have 300 Mhz.

So what will amplify that high linearly ? I think a TO 220 case would be nice, in fact a plastic TO 220 would be alot better as I won't have to insulate the tabs and there would be less radiation. Altogether much more desirable I would say.

I haven't had much luck at Digikey. I select my parameters and mostly the thing comes back with no matches. I really want TO 220 plastic but when I dropped that from the parameters I got some in a funky RF type cass, round but with a football kinda shaped clamp like portion. I would really rather not use that case style, especially if the drain is internally tied to the case. It just looks like a PITA and/or it might make a bit too good of an antenna. Probably intended for grounded drain operation or perhaps to run in a metal box. I dunno, I just prefer a plastic TO 220 type, unless someone around here has a better idea.

Another thing I haven't done in a very long time, and don't even know if you can anymore, is to call a manufacturer and talk to one of their reps about it and maybe even get them to send me a couple of free samples. Do they even do that anymore ?

Of course I have no qualms about paying for them, but then again I don't need 5 KW transmitter finals either here. It's a nice scope but not that nice.

Any suggestions ? I am in a quite suggestable mood here.

Thank you.




I can't seem to get a post to the newsgroup this morning.


I think posting is working now, here goes!



Check this,


https://groups.yahoo.com/neo/groups/...s/topics/24109

2pcs MOS-FETs(D16NE) and 3pcs resistors
which I soldered on a FR4 small board.

You might send him a letter, he is asking about his frequency response.

About 8 pictures down is schematic drawing, (shows internal IC parts),
note: a possible bad resistor.

http://www.amplifier.cd/Test_Equipme...her/1725A.html

This guy did a lot of work on his.

I suspect you have the schematic, but here it is,
http://elektrotanya.com/files/forum/2013/07/Y_amp.pdf




Mikek