19632Re: [GenesisRadio] RE: TX image supression failure
- Feb 21, 2014
Some testing results:
1. I have HP-Envy 17” laptop with embedded Beats Audio sound card and Windows 8.1. Claims 24 bits 192 KHz, works 24 bits 96 KHz. External soundcards like E-MU 0204 USB don’t work well under Windows 8.1, showing many issues with noise, big delays, unstable in use. ASIO driver completely unusable due to noise bursts and luck of adjustments in software.
2. To make hardware adjustment for TX Image Rejection (TX IR) I need to go to Beats Audio control panel, choose “Listening experience” and bring slider “dialog clarity” all way up to 100%. Any other option does not affect TX IR. “Dialog clarity” should be at 100%. I can adjust by trim pot TX IR down to 20dB max below Main signal (Carrier).
3. Software TX IR adjustment little bit tricky, I have to jump back and force between gain and phase sliders. Maximum adjustment at one time by one slider no more than 3-5dB. After 10-15 adjustments I can completely suppress Image with only Carrier presenting on FTdx-3000 panadapter.
4. TX IR adjustment (hardware and software) works only with “TX IF shift” unchecked.
5. TX IR works only for set of frequencies defined during test. Let me explain: I set LO for 14.066 MHz and VFO_A for 14.076 MHz (my primary mode is JT-65A due to antenna restriction in apartment complex). After TX IR adjustment I have only Carrier at 14.076 MHz and Image appears for first 2-3 seconds of transmission and slowly sinks into noise floor. When I change LO frequency or VFO_A frequency even by 500 Hz Image appears with the same amplitude as a Carrier (hardware and software TX IR now don’t work at all). When I change LO or VFO_A frequency during transmission, image does not show up (TX IR works), after switching again to RX and back to TX mode Image appears again (frequency did not match difference of 10 KHz between LO and VFO_A at the beginning of the transmission). This behavior makes G-11 completely unusable on TX side: when I transmit JT-65 signal on 14.076 MHz and LO set to 14.066 MHz I can see Carrier and Image because real TX frequency will be little off. The same for other digital modes and voice, too.
6. I cannot uninstall Beats Audio software; it is a part of package. Without it sound card won’t work (it has been in some HP topics for a while). I cannot downgrade OS to Windows 7; I will lose manufacturer warranty on laptop. I have all HAM software (old and new) working on my laptop without any problem. I do have second computer with Windows 7 (desktop) and will try next week G-11 on that machine. I hope that my findings will help someone in a future to avoid all frustrations and difficulties with adjusting G-11. Can we start “list of incompatible devices” for G-11? This might help other users of G-11.
Oleg Gorelov KF5QCO.
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