[App_rpt-users] URIx versus URIb

[Kevin Custer]

Lu,

DMK is aware of the situation and will be shipping the URIxB with 
different resistors in the fixed attenuator between pin 21 and the 
CM119B.  Resistors R5 and R7 formed a resistive divider that for the 
CM119B is too aggressive.  R5 was a 470k for URI's with the CM108 and 
CM119A chipset.  For the URIxB, R5 changes to a 39k.  R7 remains a 68k, 
its original value.  This change fixes the low-level problem as you 
discovered.  A fix is to either replace R5 with a lower value resistor, 
solder another resistor over top of it that results in approximately 
39k.  Another is to utilize pin 9 with a outboard coupling capacitor and 
a voltage divider that suits your attenuation needs.

Going forward, all URIxB's will be supplied with an EEPROM to hold some 
settings that aren't currently command-able from ASL software.  The 
CM119B chip has two additional features which affect how the radio 
adapter works.  One is a microphone high-pass filter.  This filters 
intention is to eliminate popping of P's or other words/syllables 
similarly spoken.  For ASL, this feature serves no real purpose, and if 
allowed to be turned on, will cause reduction of CTCSS detection below 
100 Hz, especially if the signal is noisy when using the usbradio 
channel driver.  Another feature is a selectable boost amount of 12 or 
22 dB.  The older CM108 and CM119A only have the 12 dB boost amount.  
Obviously, to be compatible with older URI's this needs set to 12 dB.  
And - it appears if this is set to 22 dB, the radio adapter stops 
working. These settings are held in EEPROM and DMK will be shipping 
URIxB's with these set properly.

If you consider the CM119B has no crystal (its design eliminates the 
need for it as a cheap USB audio adapter), you have to wonder if the 
temperature stability will be sufficient for reliable CTCSS detection.  
I suppose a variance of a few cycles of audio frequency shift would have 
no effect on voice transmissions, but a few cycles of shift of CTCSS 
could mean unreliable PL detection or possibly decoding your neighbors 
PL tone.  In my opinion, the CM119B based radio adapters should only be 
used for simpleusb deployments.  Some radio adapter manufacturers have 
purchased thousands of genuine CM119A's and will continue to supply that 
chipset by default in their radio adapters.

Kevin W3KKC

On 5/10/2019 10:26 PM, Lu V wrote:
> It’s been about 10 or 12 years since I ordered a URI and I just ordered one as I ran out of them and it came as a URIb version.
> I didn’t even notice it until I started investigating while I was having trouble with reaching sufficient discriminator level and pin 21. I’m using Kenwood next edge repeaters and I have several of them. I’m finally getting around in adding a node to my Marathon Florida repeater and discovered the hard way that the URIB will not work properly I called and found out that they change the chipset and it is not as sensitive. Just wanting if anyone else had experienced this and what the resolution might be?
> I tried testing a URIb on a gm300 and found that it just barely had enough level. It actually warns you but it does work.
> There needs to be an alternative or they need to fix this because I can see this being a showstopper for a lot of people.
>
> Lu Vencl
> KA4EPS
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