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FSR radios

— Posted by johnny 99 on 5:04 pm on Mar. 17, 2002

Anyone got any deas how to boost the range and power of an fsr radio? preferably something better than attatching a 1/4 or 1/2 wave dipole antenna. thanks!!

— Posted by Just0nePepsi on 5:11 pm on Mar. 17, 2002

I tried to do this but I found no way to do it. I really don’t think there is a way but I will look around and see if I find anything.

— Posted by johnny 99 on 5:54 pm on Mar. 17, 2002

Yea, There is a shitload of nfo on the net about CB & ham mods but the fsr is new enough that I haven’t found anything for them. could be i’m just not looking in the right places! thanks for the help!!

— Posted by Just0nePepsi on 5:56 pm on Mar. 17, 2002

Anytime. By the way, does you have a jack of an Antenna Ext. If it does I might be able to help you.

(Edited by Just0nePepsi at 5:57 pm on Mar. 17, 2002)

— Posted by johnny 99 on 6:00 pm on Mar. 17, 2002

No, but I could wire one in. Didnt bother because I didnt have very good luck with extending the length of the antenna. some improvement with a 1/2 wave hanging from a tree, but I wanted something portable  what did you have in mind?

(Edited by johnny 99 at 11:02 pm on Mar. 17, 2002)

— Posted by Just0nePepsi on 6:07 pm on Mar. 17, 2002

well i was thinking taping the wire someplace on your skin. Your body makes a wonderful antenna. Try it sometime.

— Posted by johnny 99 on 6:14 pm on Mar. 17, 2002

Yea thats not a bad Idea, I did that with a crystal 27 MH tracker I built into a belt once. But what I really want is to dramatically increase the power. Do you know howmuch over the rated voltage that you can run something like that without smoking it?

— Posted by Just0nePepsi on 6:18 pm on Mar. 17, 2002

hummmmmm im not really sure but i wouldn’t test it cause those things are expensive and like you said you don’t wanna smoke it.

— Posted by johnny 99 on 6:23 pm on Mar. 17, 2002

Well I’ve got several extras, I wouldn’t mind trying it , but I’m not shure that it would work at all. And I hate to wast ne for no reason at all. I’l bet that Z would know, maybe he’ll se this and help out. (hint, hint) Thanks !

— Posted by Zambosan on 12:11 pm on Mar. 19, 2002

Increasing operating voltage won’t increase the transmitting power in a useful manner.  The analog RF and IF gain/mixing stages are carefully designed to keep all of their components operating in linear mode.  If you changed the supply rails, you’d screw with all the bias points and cause clipping and quite likely fry some silicon (or GaAs, whatever the case may be :)).  If you want to increase reception, your best bet is to use a better antenna; one with a high quality (Q) factor that is optimized for your frequency range.  You want to maximize the bandwidth of interest, and minimize contributions from out-of-band signals.  I’m not sure what the frequency band is for family service radios off the top of my head, but you could look it up pretty easily (try FCC.gov mebbe).

— Posted by johnny 99 on 8:28 am on Mar. 20, 2002

I would actually, prefer to boost the output.

— Posted by Zambosan on 10:43 am on Mar. 20, 2002

Then your best bet would be to get an RF amplifier and a matched antenna, and tap the line-level Tx signal before it goes into the on-board antenna driving circuity.  You’ll want to disable the transmit from the handset itself to minimize interference at shorter ranges.  You don’t want to drive the existing antenna with a stronger signal than the system was designed for; the receive circuitry may not be able to handle the reflected power, and at a minimum it would have to deal with more near-end signal making it through the Rx filters.  This is most likely going to be useful for a fixed location, the resulting setup will probably be far from portable.

— Posted by johnny 99 on 7:55 pm on Mar. 20, 2002

OK!! thanks very much zan, that is just the sort of thing that I was trying t find out. I’l have to do some research and then see what happens . THANKS.

— Posted by johnny 99 on 1:57 am on Mar. 21, 2002

Well ZAN, I was thinking about what you said.  I have a 5 W handheld crystal driven CB, would it be possible to use the RF output from the fsr in place of the crystal ? that Idea appeals to me greatly, but I have no idea if it would work, or if not why? thank you for your help!

— Posted by Zambosan on 10:04 am on Mar. 21, 2002

No; the crystal is just a quartz crystal that is used as the resonant component of an oscillator.  This generates the carrier frequency, and the analog signal from the microphone is modulated with it by a multiplier (mixer) circuit.  This translates the voice information to frequencies that can be practically transmitted.

Why not just use the CB? 🙂  They can get decent range, depending on the area.  What exactly are you hoping to accomplish?

— Posted by johnny 99 on 10:35 am on Mar. 21, 2002

looking for range. my fsr will caarry about 3 kilometers at 10mw  , at a couple of watts I would think you could transmit a helluvu long way. Just screwing around mostly. thanks.

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