A presentation about 630m antennas at the 2018 Dayton Hamvention Antenna Forum on Friday, May 18, at 2:45 PM EDT. The material covers both transmit and receive antennas. Hopefully it will inspire more operators to put 630m stations on the air. Thanks to K3LR for the invitation.
Slide Deck (PDF) – click image below to open/download:
Presentation Video:
The original PP 814 transmitter used for Field Day this year has been rebuilt into a 6ft wooden rack with new power supplies and some changes to the RF sections. The amplifier’s HV supply now uses a recently acquired UTC S-48 transformer (refinished in gloss black with a wrinkled top plate) with taps for 1kV, 1.25kV, and 1.5kV. These taps can be selected via banana jacks/plugs on a strip of bakelite between the transformer and the 866 mercury vapor rectifiers.
There are additional supplies for the filaments (6.3VAC and 10 VAC), the oscillator and doubler (75V and 225V regulated), buffer (600V using 816 mercury vapor rectifiers), amplifier screen (300V using 816s), and amplifier bias (-90V regulated with a 874), all of which, including the HV supply, populate the lower four decks.
The exciter was modified from it’s FD configuration, now using an 89 ECO oscillator choke coupled to a 42 Class A buffer (plate tuned to second harmonic of ECO grid) followed by an 802 buffer/driver. Operation is much more stable than with the original two-stage circuit.
The amplifier now uses a pair of 814s in push-pull, providing more output power than the original PP 804s.
The antenna tuner is also being physically reconfigured, putting the RF current meter in the center of the panel and the tuning capacitors on either side, similar to many period tuners. The circuit itself is unchanged.
The plan is to operate it Field Day style from the back porch in the PA QSO Party (SOLP CW only – Crawford Co.) and well as on 630M Sunday night (0000Z Monday), which is the first day of Amateur operations on the band for most stations.
This was my first NA Sprint win! Conditions and activity were down, but slugged it out with decent first and third hour rates. Always an honor to compete with the sharpest group of CW contest ops in the country.
Top Ten Scores Call Score BndChgs Qs Lost 00Z 01Z 02Z 03Z NO3M 13,545 148 4 107 73 87 48 N9RV 13,288 132 1 108 62 72 60 K4RO 13,112 142 5 94 73 79 52 N5KO 12,728 94 4 99 70 66 61 N4AF 12,716 132 8 101 73 66 49 W9RE 12,470 118 5 96 69 78 47 N3BB 12,384 88 3 100 66 68 54 K0RF 12,364 76 7 81 71 74 55 AA3B 11,792 121 2 91 61 68 48 N6TV 11,726 72 0 101 69 63 53
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