Monday, October 26, 2015

FT-707 repair (11) un-converting from CB to 10m

One of the FT-707's that I aquired recently had the CB conversion on band 10A to 10D, that is the allowed CB band in most countries and also the pirates low's and highs spread accross the 10A to 10D band switch.

The hardest part here was finding the right Crystals, the few that Yaesu dealers still have in stock are extremaly expensive.

I had sorted that a regular 14.318 computer crystal would work on the 10m B position (oscillating at 42 .954), very near the 42.987 as standard on the radio.

Here's the local oscillator table for 10m

Now I acquired some less expensive crystals very near the factory frequency and can get coverage from 27.9Mhz to 30Mhz (less 79Khz in the end) on the four segments covering all the 10m band plan.

Low part on the 10A position:

High part on the 10D:

Now it's a true amateur radio, not a CB one.

Since the pin's on the new crystals were larger than the existing ones I made some terminal adaptation, that's why they are higher than the one in the 10mB place, second from the left.

I needed to put new coils (new cores and rewound) for 10mA and B, due to previous expert that touched the radio, that was covered in a previous post.

Crystals used were these ones:

10m A - 42.444 Mhz
10m B - 14.318 Mhz (on the overtone)
10m C - 43.444 Mhz
10m D - 43.888 Mhz

Have a nice week!

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