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A PIC-based audio source for locking a VHF oscillator
Several years ago I decided to build a weather satellite receiver from scratch. It is described here - link.I didn't really need a weather satellite receiver, and I could have easily bought a kit...
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The most sensitive repeater on Earth?
It first glance it would seem be the height of hubris to make a claim about "the most sensitive repeater, ever, on Earth" - but the title refers, instead, to a rather technical question: Just how...
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Gate current in a JFET! (The development of a very sensitive,...
Back in 2007-2008 I was working on a equipment "new" ham band - for me at least - the one that is now labeled as "...above 275 GHz" in the FCC rules. As you might expect the most accessible portion of...
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6 meter cycloid dipole for circular polarization
A 2-meter version of this type of antenna (the Cycloid Dipole) has been discussed here before - see the August 5, 2013 entry, "A Circularly-polarized 'Omnidirectional' antenna" - link.Way back in 2000...
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Adding FM to the mcHF SDR transceiver
This has been one of those "Rabbit Hole" features.In the past I have stated several times on the Yahoo Group that I would not be adding FM to the mcHF (a completely stand-alone QRP SDR HF transceiver)...
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Repairing the TUNE capacitor on the Heathkit HL2200 (SB-220) amplifier
Figure 1:The front panel of the HL-2200 amplifier - which is really just a slightlymodernized version of the SB-220.Click on the image for a larger version.Earlier this year I picked up a Heathkit...
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FM squelch and subaudible tone detection on the mcHF
In a previous installment ("Adding FM to the mcHF SDR Transceiver" - link) I described how the demodulation of FM signals was added to the mcHF SDR transceiver. Being able to receive FM implies the...
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Minimizing VHF (and HF) RFI from electronic ballasts and fluorescent tubes
Several years ago we started replacing the old, "iron" ballasts with T-12 fluorescent tubes at my work with T-8 tubes and electronic ballasts. The program to do this was along these lines:When a T-12...
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Adding FM transmit to the mcHF transceiver
In previous postings I wrote about how FM reception - including squelch and subaudible tone detection - was accomplished on the mcHF. As is often the case, it is usually more difficult to receive a...
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Homebrew Drake TR-3 power supply
Years ago, I was a teenager with a novice license, I got for a combination Christmas/Birthday present a "brand new"(to me) Drake TR-3 transceiver - but it had no power supply.What to do?Fortunately, I...
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Using "Ultracapacitors" as a power conditioner and ballast for transient...
The problem of "high impedance" power sources:The title serves to illustrate a problem frequently encountered when trying to power a device that operates with a high peak current: Your energy storage...
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The solar saga - part 1: Avoiding interference (Why I did not choose...
Back in November I decided to get some solar (photovoltaic) "grid tie" power generation installed at my house. I decided that the best place to install this was on the roof of my detached garage...
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Combatting scintillation effects on optical voice links
One interesting aspect of the amateur radio hobby that is rarely discussed is the use of the "Above 275 GHz" bands. While one might, at first, think that this might require some exotic "componentry"...
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Audio breakup on the JBL 4315B speaker
Over the past several weeks I noticed a problem with one of my JBL 4315B 4-way speakers: It sounded as though the woofer was "breaking up" - that is, there was occurring what sounded like some sort of...
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A 1:1 balun was the best choice for feeding the horizontal loop...
Years ago I bought a Heathkit SA-2060 (non "A" version) 2kW-rated antenna tuner at a local swap meet for a good price. While not as heavy-duty as some of the venerable Collins or Viking tuners, it had...
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Fixing the squealing auto-tuner motors in the Kenwood TS-450
This year I was setting up one of the club's Kenwood TS-450s in preparation for ARRL Field Day: We had already set up the tents the night before and I was now laying out the radios. Since it was...
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A low-voltage disconnect for 12 volt lead acid and lithium batteries
Figure 1:The as-built and working prototype constructed.Click on the image for a larger version.There are two things that you don't want to do with any rechargeable battery on a routine...
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The solar saga - part 2: Getting the system online
In part one (March 2, 2016) I wrote about why I chose to use a series string inverter system. (Hint: It was to prevent radio-frequency interference.) To read part one, click on the link here: The...
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Automatic volume tracking for a TV
A couple of years ago I was given a non-working 50" Philips flat-panel TV. As is often the case with these things, there was actually very little wrong with it and in this instance it was a pair of...
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On the winding of power chokes and transformers: Part 1 - Chokes
There are projects that homebrewers undertake that seem not to make sense when one considers the amount of time that it takes to do that thing - but then again, this is often the case when one builds...
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