|Programming the Freq-Mite for a Ten Tec 1330 radio:
Installing a Freq-Mite in a Ten Tec model 1330 QRP radio can be a little confusing when it comes to programming the Freq-Mite so it works correctly. Unlike the 80 meter, 40 meter and 20 meter models, the 30 meter model 1330 has an unusual I.F. frequency of 14.31818 MHz.
The manual for the Freq-Mite is very good and informative but misses making two key points:
– Always round-off the I.F. frequency to the “thousands” place – or 3 numbers to the right of the decimal point such as 7.123.
– Find the programming matrix numbers that have the fewest jumpers.
Since the 1330 has an I.F. of 14.31818, I just dropped the last two numbers and used the I.F. value of 14.318. As I found out the hard way – this is WAY wrong. The reason is that I had to program the Freq-Mite for that “318” number as per the Freq-Mite manual. The mathematics worked out to be:
318 = 256 + 32 + 16 + 8 + 4 + 2 (for a total of six (6) jumpers)
Programming the Freq-Mite in this manner resulted in an audio frequency readout that was NOWHERE close to accurate. As with so many things in life, mathematically it should work but it does not. Perhaps the number of jumpers was too much for the PIC chip to process but I’m just guessing.
The solution is to “round-up” the 14.318 MHz figure to 14.320 MHz. The mathematics for this figure works out to be:
320 = 256 + 64 (for a total of two (2) jumpers)
Programming the Freq-Mite this way makes everything work correctly and accuracy is still within the 1 KHz specified in the Freq-Mite manual. NOTE: The Freq-Mite needs to be set for “INVERTED” mode – pressing the push button when “I ??” is sent – every time the radio is turned on since the VFO essentially tunes backwards.
Installation Notes: As others have noted on the Internet – such as the fine presentation on the N5ESE web site http://www.n5ese.com/tt13xx_mods.htm#freqmite – the “RF IN” orange wire is connected to C69 at the output of the VFO second buffer amp. The “AF OUT” green wire is connected to the high side of the AF gain pot R6. I found that I did not need to use any dropping resistor with the AF OUT line. As such, the volume of the Freq-Mite output was not too loud and is clearly heard above the background band noise. Using a 220K dropping resistor made the Freq-Mite output too low to be heard against background band noise. Your mileage may vary as they say.
Also, since I didn’t have that many slide-on jumpers for my first attempt – ok, I lost them – I simply put a solder bridge between the pins on the bottom side of the Freq-Mite board. This is very easy to do AND very easy to undo with a solder sucker. Works great.
The Freq-Mite is a genius device and my thanks to the Four State QRP Group for continuing to offer it at such a great price.