snyderw@pawl22.pawl.rpi.edu (Wilson P. Snyder II) (05/04/88)
I am a member of a club which uses Radio Shack headset walkie-talkies. We are having a problem with the range of these units, so I replaced the antenna with a longer, common wire which runs through several rooms. Now, the problem is that this decreased the antenna gain, so now I need to boost the power output of the radio. I assume that the radio was at the 100mw FCC limit (47 MHz), but since the antenna is now less eficient, boosting should be possible. So, what I am interested in is a small 9Vdc circut to boost the radiated antenna power. Thanks. ______________________________________________________________________ Wilson P. Snyder II snyderw@pawl.rpi.EDU 318 Crockett Hall, RPI 518-276-2764 Troy, NY 12180-3590 802-658-3799 in summer ______________________________________________________________________
sfq@bcd-dyn.UUCP (sfq) (05/05/88)
> We are having a problem with the range of these units, so I replaced the > antenna with a longer, common wire which runs through several rooms. > > So, what I am interested in is a small 9Vdc circut to boost the > radiated antenna power. Replacing the antenna was a no-no. ESPECIALLY replacing the antenna with one longer than 45 feet (actually, 15 meters). And now you want to add a footwarmer to it. There's a reason those radios have limited range--they're *supposed* to. What will nearby people who are trying to use their radios do when you've begun to block them out with high power? Well, they could put on an amplifier... -- Stanley F. Quayle UUCP: cbosgd!osu-cis!bcd-dyn!sfq (614) 424-4052 USPS: 505 King Ave., Columbus, OH 43201 N8SQ @ W8CQK Fido: Stanley Quayle, Node 1:226/610 My opinions are mine. What more of a disclaimer could you need?
johng@trwind.UUCP (John Greene) (05/06/88)
In article <845@imagine.PAWL.RPI.EDU> snyderw@pawl22.pawl.rpi.edu (Wilson P. Snyder II) writes: > > I am a member of a club which uses Radio Shack headset walkie-talkies. >We are having a problem with the range of these units, so I replaced the >antenna with a longer, common wire which runs through several rooms. Now, >the problem is that this decreased the antenna gain, so now I need to boost >the power output of the radio. I assume that the radio was at the 100mw >FCC limit (47 MHz), but since the antenna is now less eficient, boosting >should be possible. > So, what I am interested in is a small 9Vdc circut to boost the >radiated antenna power. Thanks. > > If the antenna is less efficient now than it was before, why change it??? I think your problem is not a less efficient antenna, but a terrible impedance mismatch you introduced with the long wire. The radio is designed to have maximum gain using a 50 ohm load at the antenna, anything else is going to result in standing waves which means more power dissipated in the radio than radiated to the air. There are several ways to increase the gain of an antenna by it constuction. The easiest to implement would be to make a dipole of the proper length for 47 MHz. This may be all that you need. I don't remember the correction factor for calculating the wavelength in air but I'm sure you can find it in the library or someone on the net may have it handy to post. A properly constructed antenna may be all that you need. -- John E. Greene "People are just like frankfurters....You have to decide if you're going to be a hot dog or just another wiener" DLR TRW Information Networks Division 23800 Hawthorne Blvd, Torrance CA 90505 ARPA: johng@trwind.ind.TRW.COM USENET: ..trwrb!trwind!johng
cgs@umd5.umd.edu (Chris Sylvain) (05/08/88)
In article <1019@bcd-dyn.UUCP> sfq@bcd-dyn.UUCP (sfq) writes: >> We are having a problem with the range of these units, so I replaced the >> antenna with a longer, common wire which runs through several rooms. > >Replacing the antenna was a no-no. ESPECIALLY replacing the antenna with >one longer than 45 feet (actually, 15 meters). > The FCC gives you two choices: (1) a fixed output power into an antenna of fixed size, or, (2) any output power into an antenna of any length, but the field-strength allowable at a fixed distance is fixed. The intent is to limit the ERP of the unlicensed transmitter. Would you like me to dig up the specs. so I can cite chapter and verse ? -- --==---==---==-- .. He chortled in his joy. .. ARPA: cgs@umd5.UMD.EDU BITNET: cgs%umd5@umd2 UUCP: ..!uunet!umd5.umd.edu!cgs