Tell me more ×
Electrical Engineering Stack Exchange is a question and answer site for electronics and electrical engineering professionals, students, and enthusiasts. It's 100% free, no registration required.
up vote 0 down vote favorite
1

I am relatively new to the world of electronic components, but I've been trying to learn for a while now and I understand most of the logic behind simpler designs.

Now I'm trying to build a filter.

I need to isolate everything between 380-385 Mhz, and from what I can tell, getting my hands on a SAW filter (Crystal filter/Quartz filter?) is the best way to do it. However, I don't know where to look for one of those.

Any idea where I can get a hold of a SAW filter with that specific range?

Or what values (and formulas) I need for my components in a band-pass filter such as one of these:

enter image description here

This image describes a peak of ~250Hz and a range from 100-450Hz

share|improve this question
1  
If you don't know whether you need a SAW or a discrete component filter, you'd be better off starting out by asking that question. What are you actually trying to accomplish and what are the requirements for your filter? – The Photon Apr 10 '12 at 15:28
1  
You show an audio filter in the 250 Hz range and then ask about a SAW filter in the 380- MHz = 380,000,000 range. Which is wanted? Also, you say you need to isolate everything in the 380-385 MHz range. Does this mean isolate and keep or isolate and reject? (You say bandpass in the heading but ...) Telling us what you want to achieve is a far better idea than telling us how you want to try to achieve an unknown object – Russell McMahon Apr 10 '12 at 16:43
Sorry for the confusion, as mentioned i'm quite new at this :) What i need, is a component that can isolate a radio frequency of 380-385 Mhz, it doesn't really matter what type of component it is as long as it gets the job done (and is not to big/bulky). I do NOT not want a band-stop filter which from what I've read filters away frequencies, i need to remove everything below 380 and above 385 and keep 380-385. again, i apologize for any confusion/ambiguity I've caused! – Torxed Apr 11 '12 at 12:15
2  
@Torxed Also, do you understand the issues in constructing a circuit at those frequencies? You'll have to construct the prototype circuit on a solid ground plane, and be aware of impedance matching issues between your source, load, and the circuit you're testing. Slapping something together on solderless breadboard will not work. If you've never constructed a filter before, I'd suggest you experiment with design in the audio or low radio frequency bands before attempting to build one at UHF. – Bitrex Apr 11 '12 at 20:24
@Bitrex there's nothing to argue with, i'll probably need to either start with some lower frequencys or have someone do the grunt work for me, didn't think the solderless breadboard would impact as much as it did, it's a fun project which i'll continue in a slower pase, back to the drawingboard :) – Torxed Jun 1 '12 at 8:09

closed as not a real question by The Photon, Dave Tweed, rawbrawb, Olin Lathrop, jippie Jan 24 at 20:30

It's difficult to tell what is being asked here. This question is ambiguous, vague, incomplete, overly broad, or rhetorical and cannot be reasonably answered in its current form. For help clarifying this question so that it can be reopened, see the FAQ.

2 Answers

up vote 0 down vote

Not sure how small-time these would go, but worth having a look: http://www.oscilent.com/catalog/Category/rf_saw_filter_freq.htm http://www.johansontechnology.com/ (see "Request a Sample" link)

share|improve this answer
Worth a look for sure, thank you! Project is moving along slowly but this might do it :) – Torxed Jan 23 at 8:32
up vote -1 down vote

These devices can be purchased, but also are lossy, so you must drive them at proper levels and compensate for loss and appropriate impedances. with minimal ripple in passband to be defined and acceptable return lost to be defined also. How many did you want to buy? ;) I'm sure you can find a supplier for educational purposes, but you need a budget and a good spec to buy one.

share|improve this answer
At the moment i just need 2 or 3 to test things out and if i can get this thing to work i'll probably order a bundle of 100-500 at each time, but it all depends on how this works out. I don't even know where to begin my searches for such a component since you can't really search for "greater then 380 but less then 385 Mhz" when searching places. This is the closest i can find: elfa.se/elfa3~se_sv/elfa/… – Torxed Apr 11 '12 at 12:12

Not the answer you're looking for? Browse other questions tagged or ask your own question.