NO3M

Amateur Radio

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New 630M Tuner

December 11, 2015 / / 0 Comments

A new matching network has been installed at the base of the 630M antenna.  A 410 uH coil (6 in. diameter, #12 copper) in series with a 1000 pF vacuum variable tune the vertical to resonance.  A 10uH roller inductor is configured as an autotransformer for impedance matching, one end grounded, the other end connected to the vacuum variable, and the roller connected to the coax center conductor.

630m-tuner(click to enlarge)

The current controller in the shack (Arduino based) reads data from the LP-100A wattmeter and adjusts the remote tuner accordingly.  Currently only the SWR is monitored and one motor driven (resonance tuning).  However, the plan is to re-implement the controller to use the impedance and phase measurements from the LP-100A and adjust both the series and shunt elements in the tuner to obtain the proper matching.

HRO-5 on 630M WSPR

November 18, 2015 / / 0 Comments

I recently modified a spare “F” HRO-5 coilset (500-960 kc) to bandspread the 630M band, providing 10 divisions per kilohertz now.

hro-5ta1

There is some frequency drifting on the order of +/- 20 Hz, but I wanted to see how well the receiver would hold up decoding WSPR stations on the band. Continue reading …..

MOPA Transmitter in Stew Perry (TBDC) Warmup

October 18, 2015 / / 0 Comments

Running a newly built 1930s style MOPA transmitter in the Stew Perry (TBDC) Warmup this evening.  The transmitter is running a 89 Clapp oscillator, 802 buffer, 811 final; one of my favorite tube / circuit lineups.  Output power is approximately 75W.  The rig is keyed with a 1962 Vibroplex Champion.

160m-mopa

Thanks to everyone that answered my CQs!

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