Author Topic: EEVblog #1275 - Uniden UHF Walkie Talkie Teardowns  (Read 1277 times)

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EEVblog #1275 - Uniden UHF Walkie Talkie Teardowns
« on: January 02, 2020, 09:29:47 pm »
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.

 

Offline kcozens

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Re: EEVblog #1275 - Uniden UHF Walkie Talkie Teardowns
« Reply #1 on: January 02, 2020, 10:58:35 pm »
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.
« Last Edit: January 02, 2020, 11:02:55 pm by kcozens »
 

Offline johnlsenchak

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Re: EEVblog #1275 - Uniden UHF Walkie Talkie Teardowns
« Reply #2 on: January 02, 2020, 11:13:55 pm »

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

John Senchak "Daytona  Beach  Florida "
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Offline tarasv

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Re: EEVblog #1275 - Uniden UHF Walkie Talkie Teardowns
« Reply #3 on: January 03, 2020, 05:34:18 am »
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.
 

Offline CJay

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Re: EEVblog #1275 - Uniden UHF Walkie Talkie Teardowns
« Reply #4 on: January 03, 2020, 07:52:20 am »
As commented on the video...

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 micro looks like it could be an ARM Cortex M0 variant given the limited pinout I can deduce from the video, possibly one of the Silicon Labs variants like the  EFM32ZG222FXX?

If that's the case there could be factory programmed bootloader available using the TXD/RXD pads, even if I'm way wrong about the Cortex, there could still be a bootloader, for instance many of the Renesas chips used in radio gear have one.

So, where do I get one of them for $15AUD?
M0UAW
 

Offline tchicago

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Re: EEVblog #1275 - Uniden UHF Walkie Talkie Teardowns
« Reply #5 on: January 03, 2020, 07:46:48 pm »
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.
 

Offline aRGee

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Re: EEVblog #1275 - Uniden UHF Walkie Talkie Teardowns
« Reply #6 on: January 04, 2020, 11:05:58 am »
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.
 

Offline CJay

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Re: EEVblog #1275 - Uniden UHF Walkie Talkie Teardowns
« Reply #7 on: January 05, 2020, 10:19:37 pm »
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.

Not my first rodeo but thanks, yes the filter would need to be altered for 2M, you'd probably get away with it on 70CM and you would need to change the antenna hence 'hack' (I'm old school, hacking refers to the hardware as well) but the RDA1846 itself is designed specifically for dual band use so it'd be trivial to set up for 2M, the real trick is in discovering which processor it uses and reprogramming it or even replacing it.

It's far from good idea if money is the primary concern as you can buy the Baofeng and variants for not a lot more than the little Uniden but it would be fun.
M0UAW
 

Offline ali_asadzadeh

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Re: EEVblog #1275 - Uniden UHF Walkie Talkie Teardowns
« Reply #8 on: January 07, 2020, 12:48:14 pm »
Dave Please add the datasheets links :)
I'm a Digital Expert from 8-bits to 64-bits
 

Offline Lord of nothing

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Re: EEVblog #1275 - Uniden UHF Walkie Talkie Teardowns
« Reply #9 on: January 07, 2020, 03:35:38 pm »
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.  :-DD
Made in Japan, destroyed in Sulz im Wienerwald.
 

Offline DH2ID

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Re: EEVblog #1275 - Uniden UHF Walkie Talkie Teardowns
« Reply #10 on: January 07, 2020, 10:57:15 pm »
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
 


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