[App_rpt-users] TK-820 Config Question (answered)

REDBUTTON_CTRL jrorke at cogeco.ca
Mon May 22 06:36:26 EDT 2017

Scott and others, just an FYI. Some people get caught by the active low 
signalling on the URI.

What I mean by that is the URI input lines like to see a signal that 
goes to ground. It doesn't care for input voltage applied but does care 
if the inputs are grounded.

This is true for active hi signals (signals that are normally ground 
then go hi when a signal is present) or active low (signal is hi then 
goes to ground when signal is present).

The COR and PL inputs are internaaly pulled hi and have dc blocking 
diodes to prevent over voltage damage.

So in some cases the voltage swing from the connected radio doesn't pull 
the lines to ground but does source a dc voltage change.

So depending on how the logic is set the URI may not see the change or 
may think the radio is receiving all the time and time out the node.

So for active low the "Corfrom" should be set for "usbinvert". For 
active hi signals the "corfrom" is set for "usb".

If it looks like the radio cant pull the COR to ground then an NPN  
transistor can be employed to pull the line low.
It the transistor is used then the logic set for cor from should be 
changed to the opposite from above as the transistor inverts the logic.

hope this helps.

Jon vA3RQ

On 5/22/2017 6:30 AM, Scott Westerman wrote:
> I was able to get the 820 up and running with this configuration.
> Name is:         usb
> Rx Level:        500
> Rx no-delay:     0
> Rx audio-delay:  0
> Tx A Level:      500
> Tx B Level:      500
> preemphasis:     no
> deemphasis:      yes
> plfilter:        no
> rxboost:         yes
> PTT:             Active LOW
> PTT status:      Un-Keyed
> CTCSS (input):   CM108/CM119 Active HIGH
> COS (input):     CM108/CM119 Active LOW
> COS (test):      Un-Keyed
> COS (composite): Un-Keyed
> Hope this is helpful for those who may need the info.
> Scott W. - W9WSW
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