Re: transmit images with Rocky
- Thanks Tony,
I am using the J2 out jack on the break out box to feed I/Q into the
transmitter. I checked the cable and connections with an ohm-meter
and the I & Q inputs are not shorted together and all the cable jacks
and sockets are in good order.
I monitored the input on the R & L pads on the board with my Delta 44
set to -10 dB and with the 20m CW xtal selected, and found the output
power with one tone (Rocky transmit test) 0.65 watts.
With these settings I measure about 2.0 V P-P on C3 and C10. I
checked singal level by placing the scope probe on the top of R3 or R9
R6,R12, R8, & R14 are found all to be at just above 2 V P-P. The
same voltage appears on R5 and R11.
With the two tone test, power out went down to 0.275 watts
If I change the sound card settings to + 4 DB the one tone test gives
1.5 Watts out. If, on the Rocky transmit tab settings I reduce the
gain until the power out reads just under 1 Watt there are still
images. I think + 4dB is too high with the Delta 44 as I measure >7
On either sound card setting (-10 dB or +4 dB there are images).
There is probably some really simple explanation for all this -- but I
have not been able to find it. Further suggestions will be most
--- In firstname.lastname@example.org, "Tony Parks" <raparks@...> wrote:
> Hi Earl,
> Please check the TX I/O output setting. Make sure the TX output is
no more than one watt.
> Tony KB9YIG
> ----- Original Message -----
> From: tj_alberta
> To: email@example.com
> Sent: Friday, November 30, 2007 9:22 AM
> Subject: [softrock40] transmit images with Rocky
> 1) All of a sudden I am getting transmit images with rocky. Both in
> CW and BPSK. For example, if I am 10KHz above the center freq then
> there is an image every 10 KHz above and below center freq; if I am 15
> KHz from the centre freq the images are +/- 15 KHz. These images are
> real - I can hear them on a separate receiver. Sound card settings
> look alright. Help? I have worked over 15 countries on QRPp BPSK
> this week and would like to fix the bug asap.
> 2) With Power SDR I am only transmitting a CW signal on the center
> freq. and it is very weak - can't find a way to increase power out. I
> am getting full power out with Rocky. I remember I had this problem
> last year with the 40m RXTX but cannot remember the solution.
> Thanks in advance for your suggestions.
> Earl 4Z4TJ