Gordon,
The Startech USB dongles with the C-Media
soundcard are pretty good quality, and low noise floor.
$14 at Newegg:
Regards,
Rod
On 05/03/2018 08:05 AM, Gordon Gibby
wrote:
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?I should try that with the cheap $5 dongles we use locally for
sound cards for HF and packet.....I bet they aren't near as
nice....
gordon
Hi All,
Some time ago I was curious about the
quality of embedded sound cards in my old
Dell laptops, so I connected two of them together with
audio cables, and ran
FLDIGI on both of them,? in PSK31 mode.That mode shows IP3 information.
I simply used
audio-to-audio connections, with no intervening TX and
RX.?
I was stunned to see that IP3 was in the
-80 dB region! I was impressed
with the quality of the built-in soundcards.
That means it is possible to get a coarse
IP3 measurement on a uBITX
using a laptop and a reasonable quality auxiliary
receiver, listening to PSK31 from the uBITX.
The measurement would certainly be good
enough to give IP3 indications
when adjusting TX RF drive levels, and mic gain, and
soundcard output levels.
Be careful not to overload the aux
receiver, and turn off the AGC.
Another possibility is to use an audio
spectrum analyzer program on the receiving
PC to see the IP3 and IP5 peaks.
Free test equipment!
Rod KM6SN
