Many UV-3Rs users experience a very low power output on the VHF HAM band in “low” setting.
It has been measured to be at around 100mW at 145 MHz instead of the advertised 1W. This
behavior is normal.
SP3SWJ has found a hardware fix for this - replace inductor L19 with 220nH. This will then give
1.3w on low power on VHF. See:
http://sp-hm.pl/attachment.php?aid=3755
http://groups.yahoo.com/group/UV-3R/message/3795
After the modification the 2nd harmonic is at a lower level, and the output waveform looks like a
true sinewave.
How to increase output power?
There are no known modifications to increase the output power. Besides, there would probably
be too little heatsink to dissipate the excess heat (making it a good “pocket warmer”) and
surrounding components and PCB traces might not be designed for the excess current drain
(turning the UV-3R into a smoke signals transmitter). Let alone a much shorter battery life.
Remember: one S-point is 6dB; doubling the power just adds 3dB to your output. So with an
increase from 2W to 4W you would only gain half an S-unit.
If you need more power:
●
buy a more powerful transceiver
●
buy an external power amplifier
●
use a better antenna
How to disassemble UV-3R?
Taken from message #342
(http://groups.yahoo.com/group/UV-3R/message/342)
by Clint:.
- Set down a piece of cloth on the workbench to capture screws and prevent the
front panel and display from being scratched.
- Remove belt clip
- Remove antenna
- Remove battery cover and battery
- Remove screw on the knob and pull off knob from the rotary encoder.
- Remove orange silicone washer from around antenna connector.
- Remove the two screws in the battery compartment. Note if they differ from
each other and which one went where!
- Lift out the rubber flap that covers the DC and Mic/Speaker connection.
- Lift the bottom of the radio out of the case very carefully. It should go
straight up until it clears the case and at that point the portion with the
PTT/alarm/light buttons on the side should clear the case. At this point, slide
out the radio chassis from the top hole that has the knob.
- Note that the speaker connects with springs to the circuit board. If they are
bent noticeably, remember to (gently) straighten them before reassembly.
UV-3R FAQ v. 2012-01-27
Page 24
