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Test and Lab EquipmentTime and Frequency

HP 5061A Frequency Offset

by n8ur November 8, 2018
written by n8ur

I compared my old HP 5061A cesium standard against a much newer HP 5071A with high performance tube. Cesium standards are tweaked by adjust an electromagnet in the tube; this adjustment is called the “C Field.” In the 5061A you need to set the C Field manually, but the 5071A
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November 8, 2018 0 comment
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Test and Lab EquipmentTime and Frequency

OSA 8607-008 baseline frequency measurement

by n8ur November 8, 2018
written by n8ur

This is the first of several boring posts where I’m documenting the offset of a couple of my frequency standards so that I can come back later and determine aging rate.

This is my Oscilloquartz 8607-008 BVA quartz oscillator. I don’t know the last time it was adjusted, but when
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November 8, 2018 0 comment
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Ham Radio

IC-7300 Power Overshoot?

by n8ur October 4, 2018
written by n8ur

Many people use HF transceivers in situations where they back the power down significantly from full output. Examples are driving an amplifier that may require 20 or 30 watts for full output, or using a transverter that might want just a few milliwatts.

The method many modern HF transmitters use
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October 4, 2018 9 comments
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Rapsberry PiSDR

Add streaming audio to OP25 RPi scanner

by n8ur March 18, 2018
written by n8ur

Thanks to Graham Norbury, here is how to set up a Raspberry Pi OP25 scanner to stream audio to an icecast or other streaming server. I have updated my plug-and-play op25-rpi.img image at http://febo.com/os_images/ to include this capability (look for the 2018-03-18_op25_rpi.zip or later-dated file).

1. Copy the following
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March 18, 2018 5 comments
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Ham RadioRed PitayaSDRSolar EclipseTAPR Projects

Thoughts on a Wideband SDR Recording Tool

by n8ur February 16, 2018
written by n8ur

As part of the HamSci Solar Eclipse experiment, I recorded wideband data from my SDRs on the theory that capturing the data for later study might be more productive (and less stressful) than trying to do measurements in real time. I think that theory played out very well.

I
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February 16, 2018 1 comment
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SDR

Update on Update on P25 Scanner

by n8ur February 12, 2018
written by n8ur

Since my updated post on building a P25 trunking scanner with a Raspberry Pi and an RTL-SDR dongle, I’ve created a copy-and-play image file that gets you up and running in minutes.

I’ve put it (along with a couple of other RPi image files) at http://febo.com/pages/os_images/. The filenames
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February 12, 2018 31 comments
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Rapsberry Pi

Shrink/Expand Raspberry Pi Filesystem Images

by n8ur January 28, 2018
written by n8ur

This post documents a few tricks I found useful when making SD card images for Raspberry Pi projects, to minimize file size and download times while making full use of the SD card space. These instructions work for Raspbian Stretch images; not sure about older or newer versions.

The first
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January 28, 2018 0 comment
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Ham RadioSDRTest and Lab Equipment

RTL-SDR.com Dongle Measurements (Part 2 — Results)

by n8ur January 24, 2018
written by n8ur

In Part 1 I described some background about SDR dynamic range as an introduction to the measurements I did on a RTL-SDR.com v3 USB “dongle” SDR. Now for the results.

I wrote a Gnu Radio program to help measure the dongle. It tunes the dongle, sets its front-end gain,
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January 24, 2018 1 comment
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Ham RadioSDRTest and Lab Equipment

RTL-SDR.com Dongle Measurements (Part 1 — background)

by n8ur January 24, 2018
written by n8ur

I’m using several USB “dongle” SDR sticks from RTL-SDR.com. These nifty $20 devices can receive from 100 kHz to above 1700 MHz. They have a low noise amplifier in the front end that is adjustable from 0 to about 50 dB gain. I wanted to determine the impact of
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January 24, 2018 1 comment
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SDR

Update on P25 scanner — new version, and new installation instructions

by n8ur November 6, 2017
written by n8ur

Since I posted my original articles on configuring the Gnuradio-based op25 P25 trunking scanner, there’s been a lot of progress in the code. In particular, there is a new fork that changes the program to a command-line version, which saves a lot of CPU resources and also offers added features.
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November 6, 2017 8 comments
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