Thursday, July 5, 2012

July 4: Time for radio

Todays USA holiday was used as a chance to catch up on some radio projects.

First I tried out the 6GHz TWT and power supplies which failed during last weekends activities. Miraculously both now worked, one pair produced 27W the other, a bit more temperamental,  only 15W so they were put aside for operations this weekend

While having coffee at around 1700z heard the WF9XRU beacon from Virginia on 70.005 at 529.Antenna is Dipole at 20' feeding a microwave modules converter into the K3

Next the KX3 was interfaced to the Ipad to use the ISDR app as a panadaptor. An IMIC is connected to the IPAD through the Apple USB "camera adaptor". A 3.5mm stereo to 2.5mm cable was made to connect the IMIC to  I/Q output of the KX3.  Note the demodulated audio comes out of the "out" connector of the IMIC, NOT the Ipads speaker, so this was fed to some amplified speakers I have that are normally used for the HPSDR. It worked well but it took me ages to find how to set the vertical signal axis. I eventually found the answer on the ISDR yahoo group. This setting is not controlled from within the ISDR programme but is set from within the "settings" "ISDR" of the Ipad itself. Initially I had to reverse the I/Q settings in ISDR but eventually I crossed over the tip and sleeve connections on the 3.5mm connector and set the menu entry to "normal". The following is a screen capture of 20m from the Ipad

Next it was time to make some audio cables to allow the KX3 to be used on digital modes. Unlike the K3 the KX3 does not have isolated audio inputs and outputs which in the past I have found essential to avoid ground loops. Luckily I had previously made a box containing 2 audio transformers to isolate the audio paths for my now sold FT847. receive and transmit audio paths so matching cables just had to be made. The audio comes out of the KX3 from the 3 pole 3.5mm speaker connector. The transmit audio input to the KX3 and the PTT signal  were input to the KX3 via the 4 pole 3.5mm MIC connector using a resistive divider. the speaker output Voltage from the computer is far too high for the KX3 mic input. To try it out I used JT-65HF to have a few QSOs with success. It also drives the new version of Argo used as a QRSS grabber fine.

Finally I installed the Hetrodyne App for the HPSDR on my ipad.This provides a panadaptor display and can decode various modes (USB, LSB,CW etc). The LAN port of the Metis card is connected to a Netgear WNCE2001 configured as an access point which the Ipad can see from anywhere in the house. Now I am glad I upgraded to a 802.11n WIFI router. The following is a screen capture from the Ipad

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