EEVblog #1275 - Uniden UHF Walkie Talkie Teardowns

[EEVblog]

How much has UHF technology progressed in 20 years?
A teardown of a 2000 vintage Uniden 500mW UH040 UHF Walkie Talkie to a modern kids 500mW version at half the size and 1/10th the cost!
Bonus UH750 5W teardown.

[kcozens]

The AT1846S is an SDR based device based on the block diagram. You can see the 90 degree phase shift in the receive path followed by blocks that mention I and Q. The extra tranny in the receive path may be used along with the RSSI output from the AT1846S for squelch. I was waiting for Dave to have a poke at the serial interface to see what messages it outputs when it is turned on.

[johnlsenchak]

Hey Outback Dave

Wouldn't those custom  ASIC  chips also  contain   "quartz  lock  loop"  circuitry   for   channel selections, since it also   drives the display  .  You real didn't say  if  those
units  where multi-channel


In  the  early  eighties I use  to lust over the Radio  Shack  walkie  talkies  that  where 40 channels  and put out  1 watt

[tarasv]

Just to compare with 10 years of progress. I opened my 10 years old Motorola walkie talkie. Same toy size as kids Uniden. But lot of discrete components, trimmers, three crystal oscillators etc and only 55 CAD for three of them and charger.




 Interesting, did Motorola any profit on them.

[tchicago]

That RDA1846 is the chip used in the Baofeng UV-5R, which means the radio is *far* more capable than just the Australian UHF CB allocation, it'd be hackable for 70CM ham use too, hell it may even be possible to get it to work dual band on 2M as well.

The sequence of analog filters between power amplifier and antenna is tuned to the specific band. I.e. even if you hack the chip to output a frequency outside that band, it will be suppressed by that filter. Same applies to the receive path. Antenna is also made for the specific band and will significantly less effective outside that band.

[aRGee]

As mentioned by another poster : the Baofeng uv-5r .
Dual band radio, VHF and UHF, 8 watt, recharchable battery for around 21 euro including delivery from China. Even more value for the money then the Uniden. I read a few things about them, most people were very happy with this porto, but  it's of course not perfect. I remember buying my first porto for around 350 euro's around 25 years ago, a single band radio...It's incredible.

[ali_asadzadeh]

Dave Please add the datasheets links

[Lord of nothing]

Well we in Europe have some Similar called PMR446 with 8 / 16 Analogue and Digital Channel depend on the Country.
Here it relay depend on the Radio Quality from with side the Company come. There are this crap cheap Radio poor design and the Radio who are "just" reduced power to 0,5W and a little bit of Software Trickery.

I would NEVER recommend to anyone who use them for Business use an Analogue one. Here Supermarked use them. Its funny when I have Time I annoy there Employees with Questions. 

[DH2ID]

Hi Dave,
about the wire badly soldered in your "professional" WT:
It is important to reconnect it to the shielding and it should
be resoldered (taking the surplus amount off).
I'm more into hamradio and emergency radios, repairing
them as far as I can :-)
As I volunteer for our Civil Protection Service and the
Red Cross, my thoughts and prayers are with you Aussies
facing the terrible fires.
Alex DH2ID