homebrew – Page 3

Tag: homebrew (page 3 of 3)

630M AMRAD transverter retired

The AMRAD transverter has been retired. In it’s place is a new transverter design by VK3XDK: see here.

Previous Transverter

Three AMRAD based converters are used for frequency conversion using a 10 MHz LO derived from a GPS disciplined reference oscillator (modified Trimble Thunderbolt). An Elecraft K3 is used in conjuction with the transverter for dual receive and transmit capabilities, also disciplined using the 10 MHz reference (K3EXREF option).

For transmit, a W8DIZ 10W linear amplifier follows one of the AMRAD converters (down conversion) and feeds a modified (KN8AZN) Communications Concept EB-63A 100W amplifier. Maximum power is about 110W.

Open Wire Transmission line

August 15, 2010 / admin / 0 Comments

I recently started experimenting with a couple Lazy-H antennas for 10 and 15 meters. Dipole lengths are a little under 1 wavelength so as to maintain half-power points at approximately +/- 30 degrees (60 deg beamwidth). This maximizes gain while allowing a pair of them aimed 60 degrees apart to cover all of the contiguous US (180 – 300 degrees from WPA).

The Lazy-Hs are fed with ladderline in a distributed feed manner, ie. a length of ladderline is used to connect the upper and lower “dipoles” with NO TWIST, and the main ladderline feeder is connected exactly midway along the phasing ladderline. This maintains equal phasing vs. other feed methods which require attention to element lengths and spacing, and moreover are relatively single frequency methods.