[hpsdr] observation: PowerSDR T/R TUNE == no delay

[Graham / KE9H]

Ken:

Is your relay arranged such that the transmitter is connected directly 
to the receiver?

Usually it switches the antenna between the transmitter and receiver, 
and cannot
connect to both at the same time, or ever connect the transmitter to the 
receiver.

The isolation through most relays is not enough to prevent from overloading
the receiver A->D during transmit.  Overloading it does not damage it, 
(provided that
you are not putting more than +7 dBm into the preamp), it just drives it 
non-linear
for the duration.

PowerSDR ignores the overload message from the A->D during transmit, and
what you are most likely seeing is the latency in USB communications 
allowing the
last overload message(s) from during transmit to be seen by the receive 
function in PowerSDR,
which does display the message.

In other words, probably not a real problem.

--- Graham / KE9H

==

Ken N9VV wrote:
> ***** High Performance Software Defined Radio Discussion List *****
>
> Hi, I have a PowerSDR observation and I wondered if anyone else has 
> seen it:
>
> When transmitting from the CW keyboard keyer or from paddles, there is 
> a very nice delay time that you can select to hold the T/R open 
> collector outputs in transmit before they drop to receive. This works 
> very well and is a welcome setting.
>
> However, when I use TUNE, the open collector does what it is supposed 
> to do and goes immediately into Tx mode. However when I release the 
> TUNE button, it is immediate, there is no delay. So what I see is *red 
> letters* at the bottom of the panadapter saying "ADC OVERLOAD" (scary).
>
> My guess is that I am transmitting into the Mercury Rx for a few 
> milliseconds and PowerSDR has switched instantly to Receive instead of 
> obeying the selected DELAY in either the Keyboard or on the front 
> window (next to the Break-In Enabled check box).
>
> I hope I am not damaging my Mercury with those few milliseconds of 
> 180mw TUNE signal?
>
> I am waiting for the T/R switch to come from Gerd and then I will 
> compare it to how things work with my temporary "erector set" T/R unit 
> that I am currently using.
>
> thanks for reading my email,
> 73 de Ken N9VV


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