In Belgium and don't have the rest of the homebrew shack with me but needed a dummy load and ability to measure the RF levels so knocked this one together.
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Tuesday, October 30, 2012
Quick and cheap dummy load for QRSS/QRP TX
In Belgium and don't have the rest of the homebrew shack with me but needed a dummy load and ability to measure the RF levels so knocked this one together.
Sunday, October 28, 2012
TNT Uncovered - Flea-Power (QRP) Telegraph Transmitter in the Pilot Radio's "Radio Design" magazine, 1930's
I found this article in the Lloyds Dipsy Dumpster - site, where you can find a lot of rare vintage radio articles, manuals and data sheets.
It is remarkable, that "Pilot Radio & Tube Corporation", well known as a manufacturer of the great Super-Wasp receivers, was a publisher of a Ham-Radio literature, handbooks and magazines, as well as many of early radio manufacturing companies. As for me, I like that sort of advertising much more, than modern spam in my mailbox and if it would be possible, it should be a nice choice to make this QRP transmitter using a native Pilot's parts only.
Anyway, when I've read this article, one interesting fact has drawn my attention - I can recognize the TNT when I see a TNT design, but in the text this transmitter has been described as a TPTG.. Moreover, there is a grid capacitor on the assembles view, but with a opposite description below: "condenser is not needed". So, in the article we can see that mysterious moment, when as the chrysalis becomes the butterfly, TPTG transmitter was transformed into a trendy TNT.
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Thursday, October 11, 2012
More 80 Meter Vertical
I'm finally to the point of pruning it to frequency. Along the way I've fashioned a hinged base out of a large gate hinge and two conduit hangers, I've added 40 meter capability and I've made the bottom 24' a four wire vertical cage. Top loading is provided by two 6' elements forming the top ends of two of the guys, a coil wound out of 14 gauge insulated wire on a piece of 4" thin wall PVC sewer pile and a vertical 6' element. 40 meter coverage is provided by a 9' stub (connected directly to the top of the 24' vertical cage) that makes up the top of the third guy. Additional support is provided by tying the mast to my deck railing at approximately the 9' level.
Normally this will be a winter installation. I plan to paint the mast white.
Actual on the air reports will need to wait until I finish tuning it to 3560KHz.
QRSS HB Build
Tuesday, October 9, 2012
Cable-TV Amplifier with 5 Outlets

The CATV distribution amplifier circuit is built on a piece of double sided circuit board with one trace cut out with a sharp hobby knife. It is housed in a standard metal housing, that holds the 6 F-connectors for the HF. A 7805 is used to stabilise the electrical power.
The electrical power (8..30 VDC - 50mA) enters the housing via a (1n) feedthrough-Capacitor. A single diode protects the circuit from reverse polarity voltage. A 7805 soldered to the housing (GND) stabilises the voltage at 5 Volt. Two 100nF capacitors prevent the generation of spurious signals and noise by the 7805
The HF signal enters via a F-connector. An optional attenuator (0,75 - 20 dB) gives the ability to decrease the signal strength in case you should experience interference by intermodulation products. In my situation, I ended up adjusting the attenuator at the maximum level…
After the attenuator, the signal passes through a 1nF capacitor to block DC voltages and goes into the MAR-6. The input to the MAR-6 is indicated by a dot on the body and a chamfer to the input leg.
Power is supplied to the output of the MAR-6 through a 100 Ohm resistor and a 6 hole ferrite choke (1uH). DC current will be about 15mA (3,5 Volt DC at the output of the MAR-6). Another 1 nF capacitor blocks DC and only HF signal is sent to a passive resistor splitter, made from 51 ohm carbon film resistors. Input impedance is 50 Ohm for the MAR-6. Output impedance will be a little less than 75 Ohm. The splitter is build as a 'spider web' floating over the circuit board. Each output is has a female F-connector. All F-connectors are soldered directly to the housing.
After closing the lid of the housing, the circuit should be reasonably immune to the 5 x 1.5 kW Digitenne (DVB-T) transmitters built less than 3 kilometre from my house L
Safety ground
I placed the amplifier right where the cable enters our house, and routed coax to all outlets. The housing is connected to safety-ground with a copper wire.
CATV Amplifier Power supply
For power supply, I use a non stabilised adapter. Unloaded, the output is 8,5 Volt DC, just enough for the 7805 to do its job.
Source: Cable-TV distribution Ampplifier