?? J201 - J202 N fets

[RLBJR65]

I found some J202 N fets and was wandering if they can be used in place of the J201's. Spec. sheet //www.fairchildsemi.com/ds/J2/J201.pdf

I used one in the ROG Fetzervalve and it works great, just had to re-adjust my trim pot a little to get the correct voltage.

I'm not an engineer and some of the info on spec sheets is beyond me so don't know if I'd have problems using them elseware.

These are the only differences I saw on the spec sheet.

Gate sorce cuttoff voltage is
-0.3 min and -1.5 max mA on the 201  
-0.8 min and -4.0 max mA on the 202

Zero gate voltage drain current
0.2 min and 1.0 max mA for the 201
0.9 min and 4.5 max mA for the 202

Also forward transfer admittance on the
201 is 500 umhos  
202 is 1000 umhos

I think they were only a quarter each and they had a few thousand, don't know if they still have them, but I'd like to buy a few more and post a link to my sorce if they'll work and there still in stock.

[brett]

AFAIK, in the majority of cases (99.9%) you will be able to do either a direct substitution, or a substitution with adjustment of the bias.  The difference in conductance *might* alter gain somewhat, giving a different "feel".

cheers

[RLBJR65]

Thanks, Brett

I kind of thought that would be the case. It sounded better (to me) in the Fetzer than the 201's and I had.

I didn't test any of them. I really need to stop building pedals and get some testing equipment projects done! Having to much fun though!

A quarter ea. seemed like a good price to me. I'll be by the supplier some time this week and will post a link to them if there still in stock.

Thanks again!

[RLBJR65]

Sorry, someone beat me to them, went in yesterday and they only had a dozen or so left. It was a surpluss store so who knows if they'll get anymore. Well, maybe next time!

I owe an apology to who ever PM'd me accidentaly deleted the message.
Sorry hope you read this.

Thanks again for the addvice!