Unanswered Questions

73 questions with no upvoted or accepted answers
8
votes
0answers
101 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 ...
6
votes
0answers
115 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 ...
6
votes
1answer
119 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 ...
6
votes
1answer
598 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
46 views

How to measuring ferrite core efficiency vs frequency

There is an unknown ferrite toroid. I would like to figure out whether it can be used in an audio transformer, or maybe in a 1:4 transformer on given HF frequency. The experiment I came up with is ...
4
votes
0answers
55 views

Dipole loading coil winding directions?

A single inductive loading coil in a vertical or a pair of loading coils in a dipole are commonly used to match a given total antenna length parameter to a given frequency wavelength (where the ratio ...
4
votes
0answers
58 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
53 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
0answers
207 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
26 views

How to simulate two antennas in 4nec2

I need to simulate 2 helix antennae placed side by side, and see the resultant radiation pattern. But after adding the second antenna with a separate and when I try to simulate 4nec2, only simulated ...
3
votes
0answers
39 views

Heathkit SB-102 Plate Current out of control

I bought a "technician special" Heathkit SB-102 transceiver. Everything seems to work well until I attach a dummy load and try to go through the "initial tune up" procedure in the manual. At the ...
3
votes
0answers
73 views

Where did the LP to BP transformation $ \frac{\omega ^{2}-\omega_0^{2}}{\omega\cdot BW} $ come from?

I'm not sure this question is appropriate for this site, but I feel that if anyone knows about a filter, a radio ham knows! And as a ham myself I feel I need to understand this important area better. ...
3
votes
0answers
81 views

GnuRadio RF transmission, legal and safety issues

I'm trying to run some transmit/receive RF examples that I found online using GNU Radio with USRP B200. I read and heard about some cautions in terms of transmitted frequencies here in the USA which ...
3
votes
0answers
148 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
733 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 ...

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