Illegal Part 15 Mod.

[davidmc36]

I have seen in the past a few posts on the subject of how to make
things like wireless headsets have better range. So I tried a little
illegal mod. I opened up the transmitter and found a 1/4 wave antenna
attached to the board. I removed it and started with a full wave.
Performance was degraded. I cut it down to various lengths, had poor
results on all variations (5/8,1/2)until I was back to 1/4. It was by
far the best performance. When I found it it was curled around a bit to
fit inside the case. I put it back into the shape it was and
performance was down a bit. I stood it back up straight and performance
went back up, better for sure than original. So the end result will be
that I will drill a little hole in the case so it can stand straight
up. Mod complete.

 

[fineshot1]

I do not see how that translates to an "illegal mod". You did not change the design of the product or the radiating antenna. All you did was change the shape "so to speak" of the antenna.

Also - the reason you had poor results with the other wave lengths is that a 1/4 wave is a 50 ohm match to the transmitter and the others are not without a matching coil or matching mechanism of some sort.

 

[davidmc36]

I do not see how that translates to an "illegal mod". You did not change the design of the product or the radiating antenna. All you did was change the shape "so to speak" of the antenna.

Also - the reason you had poor results with the other wave lengths is that a 1/4 wave is a 50 ohm match to the transmitter and the others are not without a matching coil or matching mechanism of some sort.

The lengths OTHER than the original would be technically against regulations, no?

Quite true that anything other than the 1/4 that it was designed with would just not match impedence.

Just something fun to try to prove a point.

 

[DPD1]

You're not really changing the electrical length... You're just changing the form. The electrical length is staying the same. Either way, I doubt the radio police will be looking for you.

Dave
www.DPDProductions.com
Antennas & Accessories for the RF Professional & Radio Hobbyist

 

[fineshot1]

The lengths OTHER than the original would be technically against regulations, no?

Perhaps - but per you - you ended up back with the 1/4 wave length so a little experimentation is a good thing, and like DPD1 said I don't think the radio police would seek you out anyway.

 

[davidmc36]

Perhaps - but per you - you ended up back with the 1/4 wave length so a little experimentation is a good thing, and like DPD1 said I don't think the radio police would seek you out anyway.

lol yeah i'm not barricading the door just yet lol

 

[WouffHong]

Oh, Yeahhh..????

lol yeah i'm not barricading the door just yet lol

Oh. yeahh???

heh heh....

 

[smokeyjones666]

Heh, I tried something similar with my baby monitor. I was having trouble with reception in some areas of the house, so I opened up the case and found a 1/4 wave wire antenna wrapped around the inside of the back of the case. I bent it so it was straight up and down, drilled a small hole in the top of the case and reassembled it. The good thing is my range has slightly improved, the bad is I can now hear my kid yelling in places in the house that I couldn't before.

 

[blueangel-eric]

what kind of radio are we talking about? This thread is vague.

 

[davidmc36]

wireless headsets

Three switchable frequencies:
911.95
912.65
913.35