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increased up to 27K or 33K. For the tone beeps path R10 (100K) can be replaced by
220K or greater.
However, the 1750Hz tone, which is used for accessing repeaters, is sent via the loudspeaker
and picked up by the microphone. If R10 is increased too much the level of this access tone
sent by the mic to the repeater will be too low.
The solution by DD5XL is to reduce R10 to 660k (2 x 330k), add a 100nf capacitor across the
unused PCB pads of C47, and add a 220k resistor across the unused pads of R46. This now
directly feeds the 1750Hz tone into the modulation input of the RDA1846 chip - an added benefit
is that the 1750Hz tone is sent even with the earpiece plugged in.
Note that the 1846 chip with the 4MHz master oscillator cannot deliver 1750Hz exactly, it's
actually 1736Hz so some repeaters may baulk at this.... (GTP)
TX lock on VHF using the supplied earpiece.
This appears to be due to RF being picked up on the cord. Get one of the larger ferrite choke
sleeves from Radio Shack or the equivalent in your country. Take two turns of the earpiece cord
through the core right next to the plug. It isn't pretty, but it works. Others have suggested a SMT
bypass capacitor of about 100pF internally on the PTT line.
On my UV-3R Mk.II I cannot change the UHF step-size
With the UV-3R Mk.II trying to change the step-size from the menu in UHF mode does not work.
The tuning step-size can only be set from the menu when in VHF mode. When the step-size is
set in VHF mode that step-size is used on both VHF and UHF.
It appears that after Serial # 311072nnnn (or thereabouts according to the Database) there is
independent VHF/UHF settings for step size on Mk II models.
My VHF/UHF receiver does not work.
The only known (through the Yahoo Group mailing list) out-of-the-box problem on a VHF
receiver was experienced by IK1ZYW on a UV-3R bought in July 2011. The problem has been
traced down to a cold solder joint in the switching diodes. The problem has been fixed with a
hot-air (re)soldering station which brought back the RTX to 100% full functionality.
Procedure to identify cold solder joints:
● work on a non-conductive surface (wood and plastic are OK)
● identify, with another receiver, a constant signal source in the band you experience the
fault
● leave the other receiver on the active frequency
UV-3R FAQ v. 2012-01-27
Page 26
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