hello can somebody help me where to find 3N187 dual mosfet, of i dont know how to make thnx

 

Welcome to AAC!

This showed up in the first search hit:
https://alltransistors.com/mosfet/c...ty=N&pd=0.33&uds=20&id=0.05&rds=150&caps=TO72

 

hello can somebody help me where to find 3N187 dual mosfet, of i dont know how to make thnx

If you mean dual gate MOSFET - its essentially 2 single gate units in casc-ode.

Motorola might still be doing similar parts with MFE prefix.

VHF and UHF DG MOSFETS were once very common in TV tuners - but I don't know about since DVB.

 

They were used as mixers in some H.F/VHF receivers, the equivalent list by D1243 should help, but I know that the 3n187 had special low capacitance protection diodes built in which may be an important feature in your application. Check out the equivalents carefully before substituting, also pin outs may be different.
Whenever I had to replace Mosfets like this, I used to use an anti static wrist earth strap, and push all four pins into a piece of aluminium cooking foil, solder the device into the circuit board, then carefully remove the foil with tweezers.
Static on these types may not completely destroy them but can cause changes in the characteristics that can lead you on a merry old dance if you are unlucky.
Also make sure the soldering iron is low leakage and suitable for static sensitive components.
You may well be aware of the above, but I mention it because others who read it may not be.

 

Welcome to AAC!

This showed up in the first search hit:
https://alltransistors.com/mosfet/c...ty=N&pd=0.33&uds=20&id=0.05&rds=150&caps=TO72

View attachment 142174

thank you, so now i have to make a model, i am new in ltspice, i dont understand little bit

 

They were used as mixers in some H.F/VHF receivers, the equivalent list by D1243 should help, but I know that the 3n187 had special low capacitance protection diodes built in which may be an important feature in your application. Check out the equivalents carefully before substituting, also pin outs may be different.
Whenever I had to replace Mosfets like this, I used to use an anti static wrist earth strap, and push all four pins into a piece of aluminium cooking foil, solder the device into the circuit board, then carefully remove the foil with tweezers.
Static on these types may not completely destroy them but can cause changes in the characteristics that can lead you on a merry old dance if you are unlucky.
Also make sure the soldering iron is low leakage and suitable for static sensitive components.
You may well be aware of the above, but I mention it because others who read it may not be.

What the TS mentioned probably pre dates protection diodes - most modern devices have them.

TV tuner DG MOSFETs have very low gate capacitance - especially the UHF ones.

AFAICR: the BF991 is good to nearly 1GHz and should have a spice model floating around somewhere.

The 991 is SMD, the 981 is pretty much the same spec in the old leaded pill type package. The 981 is hard to find unless you have a pile of old tuners stashed away.

 

What the TS mentioned probably pre dates protection diodes - most modern devices have them.

TV tuner DG MOSFETs have very low gate capacitance - especially the UHF ones.

AFAICR: the BF991 is good to nearly 1GHz and should have a spice model floating around somewhere.

The 991 is SMD, the 981 is pretty much the same spec in the old leaded pill type package. The 981 is hard to find unless you have a pile of old tuners stashed away.

I think that the 3n187 was one of the first to have the built in diodes, they where specified as being on the die and very low capacitance, Part of the advertising for them that was emphasised by the manufacturer. I can't be absolutely sure which transceiver we used to modify, may have been a Yaesu that used an unprotected dual gate mosfet as a mixer and rf amplifier that used to pop on a regular basis, fitting the 3n187 cured the problem.

 

I think that the 3n187 was one of the first to have the built in diodes, they where specified as being on the die and very low capacitance, Part of the advertising for them that was emphasised by the manufacturer. I can't be absolutely sure which transceiver we used to modify, may have been a Yaesu that used an unprotected dual gate mosfet as a mixer and rf amplifier that used to pop on a regular basis, fitting the 3n187 cured the problem.

The very famous 40673 goes back to one of the devices on the page - the part the TS has probably matches an RCA part too.

Probably long since obsolete, but as I mentioned elsewhere; Motorola more recently did MFE prefixes that were similar.

 

The very famous 40673 goes back to one of the devices on the page - the part the TS has probably matches an RCA part too.

Probably long since obsolete, but as I mentioned elsewhere; Motorola more recently did MFE prefixes that were similar.

I've still got some 40673's, probably never going to need them now though. When the T.S first posted, I went and had a look at my stock in case I had one but no luck.

 

What the TS mentioned probably pre dates protection diodes - most modern devices have them.

TV tuner DG MOSFETs have very low gate capacitance - especially the UHF ones.

AFAICR: the BF991 is good to nearly 1GHz and should have a spice model floating around somewhere.

The 991 is SMD, the 981 is pretty much the same spec in the old leaded pill type package. The 981 is hard to find unless you have a pile of old tuners stashed away.

hello i have that one, is similary to 3N187?

 

I have models DualGate:



Although this may be out of place. Perhaps you need to make repairs and do not need to calculate the circuit. But sometimes the calculation shows: is replacement permissible.

 

I have models DualGate:

View attachment 142218

Although this may be out of place. Perhaps you need to make repairs and do not need to calculate the circuit. But sometimes the calculation shows: is replacement permissible.

CAN YOU GIVE ME ;-;

 

If you use LTspice, then you can download my entire library.
https://forum.allaboutcircuits.com/...nents-models-of-ltspice-free-download.133690/
If not, then

 

If you use LTspice, then you can download my entire library.
https://forum.allaboutcircuits.com/...nents-models-of-ltspice-free-download.133690/
If not, then

i did it thank you very much have nice weken everybody, thanks

 

thank to everybody

 

hello i have that one, is similary to 3N187?

Its likely to be more superior than similar.

You should study things voltage and current rating etc and make a judgement call on whether you're likely to get away with it.

 

Its likely to be more superior than similar.

You should study things voltage and current rating etc and make a judgement call on whether you're likely to get away with it.

thnx man i am busy with study