KH6HME 1296 MHz beacon

1296.250 MHz, June 4, 2005

The beacon was originally built back in 1981 and was first installed on the Mauna Loa volcano on June 28, 1981. It had 25 watts of output power from an air cooled N6CA 7289 cavity amplifier. Paul would have to change the tube every couple of years to maintain output power. The 7289 was driven by the 1.2 watt transverter-beacon below. After 19 years it was still worked but changing tubes got to be a pain so N6XQ built up a beacon which has been running fine until an intermittant problem occured after five years of operation. It was then decided to rebuild the original beacon and upgrade the 1.2 watt amp with a 57762 power module. This upgrade delivers about 14 watts. The transverter capability was removed and it was repackaged to make it smaller. It needs +13.5 vdc at 3.5 amps.

 The original "antique" 1296 beacon. DBMs were hard to come by so rat-race mixers were used with PC mounted band pass filters, MRF571 transmit transistors and NE64535s in the receiver and U310 for IF amps.

 (Front to rear) Local oscillator board, transmit board, receiver board and 1.2 watt power amplifier. The 52601 transistor was made by WA6MEM.

 The new repackaged beacon.

 From the rear

 LO board, transmit board, IDer, keyer, 28 MHz oscillator, delay generator and 57762 power module

 The 57762 power module

 Isolator and band pass filter installed on beacon to protect it from generating any intermod products from the 950 MHz repeaters co-located at the site on the volcano. Insertion loss is about 0.65 db and rejection of the 950 signals is -55 dbc.

 looking towards antenna  looking from antenna to transmitter

 link to KH6HME page