Audio level setup on TNC-X (MFJ-1270X)

Appropriate setup of audio drive of an AFSK APRS FM transmitter is important to ensuring that the signal can be copied by all receivers in range.

Excessive audio drive results in a signal that cannot be decoded by some receivers event though it may be very strong.

The TNC-X does not have any facilities for producing steady tones for adjusting the tx audio output for the desired deviation level, so alternate firmware was developed solely for this lineup function. The regular MCU chip is replaced by the adjustment chip for the lineup then the regular MCU chip is reinstalled. Note that this is not an augmented version of the regular firmware, it is for adjustment purposes only… do not overwrite the original chip. Continue reading Audio level setup on TNC-X (MFJ-1270X)

Review of APRSTRACKER v0.11firmware

I recently built a FoxDelta FOXTRAK APRS tracker.

IMG_1208

FoxDelta supply the FOXTRAK with firmware by DK7IN, but also recommend APRSTRACKER by PE1RXQ and PE1ICQ.

APRSTRACKER v0.11 was trialled as it offered promise of a better SmartBeaconing implementation and support for altitude, course and speed reporting. Continue reading Review of APRSTRACKER v0.11firmware

Review of Ceramica ceramic bearing fans

For some years I have used Ceramica muffin fans for low noise and long life. They use a ceramic bearing which is quieter than ball bearings, but longer life than sintered bronze bearings which dry out.

FanImpeller

In the last month, I have replaced three Ceramica fans that have failed, one with less than a year’s service and two with less than one month’s service. Continue reading Review of Ceramica ceramic bearing fans