Posts

TS-790 TCXO Adjustment

Image
 In the past year or so, I have noticed that the displayed frequency for both the 144 Mhz and 430 Mhz operations of the TS-790 have been considerably off. The frequency for both units is derived from the 144Mhz PLL unit.  It has a 10.24Mhz TCXO that is multiplied by 10 or 12 (depending on band) and mixed with various other frequencies to arrive at the final target frequency. The Service Manual suggests monitoring the x10 frequency of 102.4 Mhz at TP5 on the 144Mhz PLL Unit, and adjusting the TCXO there.   10.24 Mhz Probe Point   I have an HP5334 Counter that is tied to my external GPS locked 10 Mhz standard.  This is a very stable and accurate counter, but it is not able to count above 100Mhz without an option that I do not have installed. Still, it is the best option I have for setting the PLL frequency of the TS-790.  So rather than adjusting the PLL at the 102.4 Mhz test point, I adjusted it at the 10.24 Mhz output of the unit.   10.24 Mhz Oscillator Off Frequency   The unit was off

TS-790 9600 Baud Mod

Image
I was working on a 2-meter FM radio that I have recently acquired. It had a low deviation problem, which requires a method of measuring deviation in order to fix it and adjust it to specs. While I do not have a service monitor or other direct way of measuring deviation,  I happened to recall that I had made a 9600 baud modification to my old Kenwood TS-790 that I have had since the late '90s. The modification brought out connections that allow direct FM modulation (no pre/de-emphisis), and a direct discriminator output. If I could connect an instrument to the discriminator output, I could use my HP 8640b RF Generator to feed an FM signal to the radio at various deviation settings, and record AC voltage measurements of the audio output from the discriminator.  These could be plotted on a chart and used as a reference to measure the deviation of other radios when they transmit an FM signal. Digging through my old documentation, I found a schematic on which I noted the modification. F

JuncTek Battery Monitor MQTT Controller

Image
 I recently installed some 48 volt Lithium Iron Phosphate battery packs at the Ranch to replace the 9 year old Lead-Acid batteries that had started to fail.   eg4-lifepower4-battery-48v-100ah   These are rack-mount battery packs that are intended for powering computer servers.  They are reported to work very well in an off-grid power system.  The Problem I had a problem to solve before the upgrade, in that the old 48 volt inverter I had been using in our solar power system required a programming interface to change its operating parameters to match the new battery specifications.  Unfortunately, the manufacturer wants over $400 for the required interface to make these changes.  I am unwilling to pay this extortion money for a simple device that should cost less than $100. The communications protocol and interface is proprietary, so it would take a considerable effort to hack the interface. There are two sets of parameters in dealing with the inverter/battery connections: 1. The chargin

Kenpro KR-5400 Repair

Image
We did a balloon launch at the Maricopa Hamfest just before Halloween this year. My job, as usual, was to ready the video payload, and track the balloon in order to get a live feed of the video from the balloon. I always pull out my tracking system and assemble it in the days before an event, to make sure that I have everything I need, and it is all working.  When I set everything up and did a full test run on Monday, everything worked fine. On the day of the flight, we set up the system as normal, and initial tests of moving the antennas up and down, and through their full range of motion indicated that we were ready to go. But when the balloon went up, Murphy hit.  My elevation rotor was not getting a good indication on either the meter of the control box, nor my tracking software.  This was intermittent, as sometimes toggling the controls seemed to make it work for a while.   I muddled through by manually controlling the antenna, sometimes needing to search for the balloon video dow

APRS I-Gate

Image
  APRS I-Gate Filed in Microcontrollers on Jan.05, 2022 Introduction In early 2021, I was approached to build a small, easy to use version of an APRS I-Gate. This device listens for APRS packets from your radio receiver, and forwards them to the internet to be displayed at the aprs.fi website. In this post I will detail the steps used to build and program this APRS IGate that runs on a Raspberry Pi Zero-W. The goal is to have a headless device (when desired) which automatically boots up the necessary programs and runs them when powered up. It will connect to a preferred network to forward the packets to the internet. Also included is a simple one-button shutdown routine, so there is no need for a keyboard in day-to-day operation. This process is documented on a Linux Mint machine. Utilities and details may differ for other architectures Here are links to PDF documents with build/configuration instructions… RaspberryPi_Zero_W_OS_Setup Rasp

IC-2720 Installation in 2012 Ram-1500

Image
  IC-2720 Installation in 2012 Ram-1500 Filed in IC-2720 on Jan.02, 2022 I was reviewing my photos folder today, and ran across this project from 2016 that I never made a blog post on. Here is a brief overview of that installation. I’m not providing many details, as this was done several years ago, and I can’t remember many of them. Maybe it will be useful for others with this vintage of Dodge Ram pickups. I had been using magnetic mount antennas on my 2012 Dodge Ram pickup since the time I had bought it new. I was concerned with running RF coax near any airbags that might be in the side panels of the truck. It had some badges on the side panels indicating there might be some. After owning the truck for four years, I decided to take a chance on making my antenna connections more permanent. I started by removing the dome light from the roof. I don’t remember now if I had to remove screws or not to do this.   Remove Dome Light I used a Unibit to dril