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donjonson
Post subject: Building a 16Mhz radio for Senior design project. have Q's Posted: Wed Sep 19, 2007 7:23 pm

Lieutenant


Joined: Wed Sep 19, 2007 6:58 pm
Posts: 3
Hello Very Happy This is my first post on this forum. I am building a 16Mhz radio for my senior design project and Have a few questions. I have been working in PSPICE and am ready to start building and testing.


1)What kind of capacitors should I use in my tuned amplifiers, oscillators, and filters? I have been looking online and there are so many to choose from. I think I should be using something with a small temp coefficient but what material should I use etc..

2)Does anyone know of a place online with low shipping costs and a good selection of components? I have been looking at mouser it seems to be pretty good any other suggestions?

3)In my transmit oscillator I am using an NFET to switch in and out a cap. I am having a difficult time trying to Find one in a TO-92 package with a good enough Ft. Does anyone know where I could go to get this? or perhaps suggest a better device for me to use than an NFET.

thank you for taking the time to read and answer my questions.

I posted this in the amateur radio forum first but I noticed it is pretty much a dead forum so I reposted it here. If a moderator wants to delete one of them please delete the other one.


Top

IR
Post subject: Posted: Sat Sep 22, 2007 2:51 am

Site Admin


Joined: Mon Jun 27, 2005 2:02 pm
Posts: 373
Location: Germany
Hello donjonson,

First of all, welcome to our forum!

To answer some of your questions:

Quote:
1)What kind of capacitors should I use in my tuned amplifiers, oscillators, and filters? I have been looking online and there are so many to choose from. I think I should be using something with a small temp coefficient but what material should I use etc..


In principle, you should use high Q capacitors. As for the material you are right there are materials with large temperature coefficient like Y5V. You should use X7R or X5R capacitros which have a low temperature coefficient.

Quote:
2)Does anyone know of a place online with low shipping costs and a good selection of components? I have been looking at mouser it seems to be pretty good any other suggestions?


You can try: Digikey www.digikey.com

Quote:
3)In my transmit oscillator I am using an NFET to switch in and out a cap. I am having a difficult time trying to Find one in a TO-92 package with a good enough Ft. Does anyone know where I could go to get this? or perhaps suggest a better device for me to use than an NFET.


While NFET is a good choice I would not limit myself to a specific type of package to allow more flexibility. Thre are many types of packages available besides TO-92.

Here are number of TO-92 NFET transistors from Vishay-Siliconix:

http://www.vishay.com/docs/70237/70237.pdf

Quote:
I posted this in the amateur radio forum first but I noticed it is pretty much a dead forum so I reposted it here. If a moderator wants to delete one of them please delete the other one.


posts with topics which are relevant to the Forum are not deleted.

I am moderating this forum for almost 2 years now and have met here people with reach knowledge from whom you can only learn.

Good luck

-IR







Posted  11/12/2012
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