Extended frequency range


The FT225RD was sold in some countries were the frequency range is 144-148MHz. To have a separate model for these countries is expensive and that's why it's very easy to do this fix.

I must point out that this could be illegal in some countries and you do this modification at your own risk!

The modification

The modification is so simple I don't understand why I have not seen this somewhere before. When I began to work with these pages I really did not thought about it, but since some people ask for it, here it is...
On the "LOCAL UNIT", PB-1805, there are some crystals. The crystals X03 and X04 have been bridged on all FT225RDs that I have seen. Just remove the bridges and you will have full coverage from 144-148MHz.
I also want to point out that the performance will not be as good in the 144-148MHz range as the 144,0-144,5MHz if you have removed the cap-diodes in the front end.

To do this modification legally

If you would like to do this modification legally you just have to place a relay with it's contacts at X03 and X04. Connect the relay-core so it's activated when the PTT is pressed. When the relay-contacts are closed the crystals are bridged. In this way it will not be possible to transmit on this illegal frequency band. The type of relays are not critical, but you must have two contact-closures - do not connect the two crystals to each other!
I have tested to remove the bridges, but since my receiver is optimised for 144,0-144,5MHz it's really not interesting for me and if I would like to listen on these frequencies I have a PCR1000.

Crystals for fixed frequency operation

On the "FIX UNIT", PB-1750, it's possible to have crystals for fixed frequencies. These crystals should be between 8,2-9,2MHz. I have tested with ordinary 27MHz crystals and many of them work! (Since these crystals often are using the third overtone.)
If your display is off, ie no frequency is displayed, then the crystal does not work in the FT225RD and the PLL can't lock. (This does not have to mean that the crystal is not working and the test will not destroy the crystal.)
I found some "large" crystals and they did not fit into the crystal-holder in the FT225RD. I soldered them in on the solder-side of the PCB. In this way I now have 144.050MHZ and 144.250MHz as fixed frequencies! This is very nice to have in contests and then be able to listen on beacons between calling CQ etc...
After mounting the crystal, fine-adjust the frequency with the trimmer-capacitor - individual for each crystal and located at every crystal-holder.