4
$\begingroup$

So I recently bought a pair of Wouxun KG-UV6D. We don't have the license required to operate outside of PMR frequencies, but that's fine, as we will be using these for airsoft. The programming of 8 standard PMR frequencies used is pretty straight forward, but for some reason, I am experiencing "spillover". The channels I am programming into them are these:

  • PMR 1:446,00625
  • PMR 2:446,01875
  • PMR 3:446,03125
  • PMR 4:446,04375
  • PMR 5:446,05625
  • PMR 6:446,06875
  • PMR 7:446,08125
  • PMR 8:446,09375

But when I have one set to 446,00625 and the other to 446,01875, if I send with the 446,01875-radio, the other radio will pick up a lot of static noise. So far, I have tried setting squelch level to the least tolerant level, and channged the bandwidth from wide to narrow, but it is still picking up the static. Aside from that, the static seems to interfere with my laptop, randomly interacting with my media keys (fan boost, bluetooth etc.). I have set the step to 6.25K, and I will not be using this radio to access any repeaters. Also, I need to send with a TXP of 0.5, but seeing as the radio only has HIGH (4W) and LOW (1W), I stick to the low setting.

I am programming manually, and I am very, very green to radios. What am I doing wrong?

Edit: I made a short demonstrational video of what this interference sounds like: https://www.youtube.com/watch?v=TE7MekFMx-o - Take note that I am on the wrong frequencies in this video: I misread 446.- for 466.-

Improve this question
$\endgroup$
9
  • $\begingroup$ What country/region are you in? Please add to your question. The use of these radios is likely illegal for these personal mobile radio frequencies. The main reason why is that they are not designed for or tested for compliance to the standards set for those channels. In north america our "FRS" and "GMRS" services are similar - you are only allowed to use equipment explicitly designed for and tested for this service. Without knowing what country you are in, I will guess that similar rules apply to PMR. $\endgroup$ – BenSwayne May 11 '14 at 0:31
  • $\begingroup$ You might still be able to get it to "work", but the canonically "correct" reply to this question may (depending on your laws) very well be be that you shouldn't, as disappointing as that may be personally. $\endgroup$ – BenSwayne May 11 '14 at 0:34
  • 1
    $\begingroup$ This question appears to be off-topic because it is about PMR, which is not part of the amateur radio service as defined by the ITU. $\endgroup$ – Phil Frost - W8II May 11 '14 at 11:35
  • 2
    $\begingroup$ The frequencies may be legal and license free, but you should check your local laws as it is likely that using these radios for those frequencies is not. It is certainly the case than in the UK, you must only use radios specifically designed for PMR446. This is what all the other replies are trying to tell you. One of the main reasons for this is that you can easy transmit where you are not allowed to - which you actually demonstrate doing in your video. You should look into walkie talkies designed specifically from PMR446. $\endgroup$ – Andy Smith VA7YK May 12 '14 at 20:48
  • 2
    $\begingroup$ Before voting to close this as off topic because it's not amateur radio, please see ham meta: Are non Amateur Radio discussions allowed?. $\endgroup$ – user May 13 '14 at 8:58
2
$\begingroup$

The filtering for nearby frequencies in any radio is finite. According to the UV6D Specifications, the 12.5 kHz selectivity is 60 dB. The 0.8uV squelch threshold specification is -109 dBm. 1 Watt is 30 dBm.

You're getting less than 30 dB isolation from transmitter to receiver in those tests based on the very short separation, so you're feeding about 0 dBm into the receiver from the transmitter, and the specified 12.5kHz selectivity is about 60 dB, with a squelch threshold of -109dBm, tallying up to:

0 dBm - 60 dB = -60 dBm >> -109 dBm ==> Static noise when transmitting on channels 12.5 kHz apart in the same room.

Neglecting the legality issues other answers discussed, a solution is to use the most widely separated (in frequency) channels when radios not wanting to communicate to each other are in close proximity. For example, if you have a golf course, put the caddies on channel 1 and the host staff on channel 8, and so on.

Improve this answer
$\endgroup$
1
  • $\begingroup$ Welcome to ham.stackexchange.com, and thanks for taking the tour! 73! $\endgroup$ – rclocher3 Mar 10 '17 at 21:52
1
$\begingroup$

The issue is natural, and specific to cheaper grade radios. Changing the squelch tolerence and putting a small distance between the radios (6-8 meters) nullifies the interference.

Improve this answer
$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.