[ARDF] RX1 PLL MOD

[Gerald Boyd]

The Albuquerque transmitter hunting group has been using an add on board for the RX1 ARDF receiver for some time now.

The board is called OZMOD (see http://home.att.net/~wb8wfk/equipment.html#ozmod  ) our group now has artwork for version 3 of the design ready for FAB.

We are going to send the order to the board FAB shop soon. 

Because Ozmod makes the RX1 very stable this has allowed our group to make another modification to the RX1.  About a year ago we modified the high IF in the RX1 to use a narrow band crystal filter. This eliminated a problem that we were encountering from an active mountain top voice repeater and a local APRS repeater. The APRS repeater was about 2 miles from our ARDF site and 1.175 Mhz below our hunt frequency! The original RX1 uses a wide if filter (FM broadcast type?) in the high IF. No more APRS and long winded QSO QRM encountered during our ARDF sessions.

OZMOD also extends the operating time of the RX1. This is because OZMOD is using a DC to DC converter to generate the required operating voltage for the RX1 and the PLL controller from 4 AA 1.25V size nickel metal hydride cells. We can now operate several ARDF practice sessions on a single charge. If the receiver gets turned on during impound no problem.

OZMOD also provides two VFO's that can be selected at a push of a single button. One is for the FOX and the second is for the finish line transmitter. They can be reprogrammed in the field and saved to NV memory to accommodate your event. An on course timer, ARDF cycle timer and system voltage monitor is also provided on the LCD display.

Currently we have about 12 persons wanting boards, because of the NRE charge each board will cost around $30 each ( PCB board only) the more boards we can get on the order drives down the cost. 

The boards are high quality with solder mask and screen with plated through holes ( V2.0 OZMOD photo on web site URL). A majority of the parts are surface mount. Parts can be ordered from the internet from Digikey and Newark.


When I have the final head count for boards I will go get an estimate from the FAB shop which will determine the actual cost.


Jerry Boyd, WB8WFK