Unanswered Questions
52 questions with no upvoted or accepted answers
7
votes
0answers
91 views
UHF FM power amplifier design without expensive software
I'm designing a small UHF data transceiver for the 70cm band, based on a Silicon Labs EZRadioPro Si4463 IC. Modulation is FM, 12.5kHz channel step. The concept is similar to SiLabs' AN656 application ...
5
votes
0answers
103 views
Beyond Maximum Stable Gain of a transistor
I was plotting constant-gain circles on the Smith chart the other day for a potentially unstable RF transistor.
I recently read on-line that for a potentially unstable transistor the maximum gain ...
5
votes
1answer
583 views
Doppler Shift Compensation in Inter Satellite Communication
I am currently doing a project in the area of optical inter-satellite communication (GEO-LEO).
I am using a optical carrier of 281 THz, and the Doppler shift corresponding to it is ±7 GHz. I ...
4
votes
0answers
52 views
Is it practical to use a magnetic amplifier as an AM modulator in a transmitter?
If I'm building a vacuum tube HF transmitter (say, 40 m band), obviously the simplest mode to build is CW; it's common to key the oscillator input to the final (in order to keep the oscillator running ...
4
votes
1answer
48 views
High-resolution GIS datasets of groundwave conductivity of the United States, besides the FCC?
The FCC publishes a map of estimated groundwave conductivity of the United States, but the resolution is quite low:
Are there any GIS datasets that include groundwave conductivity at a higher ...
4
votes
1answer
109 views
SNR measurement for a BPSK/QPSK signal
I have created a software (gnuradio) that performs modulation/demodulation and supports a number of modulation schemes and error correcting codes. I'm in the process of evaluating the BER vs SNR for ...
4
votes
0answers
193 views
ISS APRS Digipeater with Kam XL and ICOM IC-910H
I am trying to use the ISS APRS digipeater which transmits at 437.55MHz.
Hardware setup consists of the following
ICOM IC-910H.
The transceiver has been connected to a Windows PC running a HAM ...
3
votes
0answers
128 views
Kenwood TS-50 and USB to Serial
I paired my old Kenwood TS-50 with serial, by using FTDI TTL-232-5V-AJ USB to serial converter.
I used ideas from here:
http://steeman.be:8080/posts/TS-50%20USB%20Interface/
and here
http://i.imgur....
3
votes
0answers
692 views
OFDM spectrum, HACKRF, and GNUradio companion
I am trying to analyze the spectrum of wifi spectrum.
I getting a good OFDM spectrum with my HackRF at 2.412 GHz (from my first QTGUI Sink).
But I get nothing out of OFDM Receiver. I was wondering ...
3
votes
0answers
973 views
TS-590 Antenna Tuner Protocol
I'm looking for the protocol used by Kenwood's TS-590S antenna tuner port. I've worked as far as I can with Kenwood's tech support. They know what the pins are labeled, but don't have any information ...
3
votes
0answers
67 views
CML FX919B Forward Error Correcting
I would like to decode de-interleaved demodulated 4FSK symbols that were transmitted using the CML FX919B chip.
The datasheet only gives the following information:
Forward Error Correction In ...
2
votes
1answer
26 views
Feeding a folded dipole
Can I feed a folded dipole constructed of hollow tubing by threading coax through the element to create both an impedance transformation and balun? I have fed coax through the tubing of the dipole ...
2
votes
0answers
17 views
Grounding a chimney mounted antenna
I'm installing a new antenna mast to hold one or more antennas. The new mast will be strapped on to a chimney near the center of my house. Coax will run down the mast, across the roof, down the side, ...
2
votes
0answers
83 views
Yaesu FT-891: power drops to 50% when TNR is ON and SWR is 1.5:1
I noticed a weird behavior of my Yaesu FT-891 transceiver. I'm using it with an external autotuner mAT-30 (120W SSB/CW, 30W PSK31), which is compatible with Yaesu FC-50.
When I connect a 100W 50 Ohm ...
2
votes
0answers
90 views
GnuRadio alternative for Selector Block
Hi I want to switch between tx and rx in a flow graph with my HackRF.
I found this video that shows how it could be done.
The key component is the Selector block which is now deprecated.
Is there a ...
