Modifications for the Yaesu FT-7



19-07-1998 FT-7 modifications made

  1. VFO temperature compensation, according to article in Radcom, this did not have desired effect, nor was it necessary, and I got a compensation problem and RIT did not operate satisfactorily so I removed this modification later.

  2. extra band segment on 10m uses FIX switch. RIT must be either constantly on or off. Later I heard that someone else made a modification to add full 10m coverage

  3. Transverter connection. BNC connectors for RX and TX, RX may not be used with external antenna. TX level without PA module is abt +6dBm/2mW.

  4. TX gain. First I used an extra negative bias for CW TX gain. only -1.2V needed. later I modified the transceiver according to FT-7B, this was later changed such that TX gain was used for either SSB/CW, mike gain was set by a trimpotmeter.

  5. Noise blanker improvement (see FT-7B circuit). An extra capacitor is connected as for FT-7B.

  6. Keying. Some experiments were carried out by LA9DL and LA8AK. It was experienced that the original keying transistor would not function satisfactorily, and a AC125/126 was used with a changed circuit. A high gain germanium PNP transistor is necessary. max 500 lpm worked for CW MS 1000LPM, very little key-clicks

  7. Key jack. a new 6.3mm stereo jack was installed (where remote vfo connector was). PTT and key is connected.

  8. Mike connection was made similar to that used by kenwood. Yaesu mikes showed advantageous to use in TS-700/TR-7010. Kenwood mikes may be modified with a 47nF series capacitor, but output will be limited.

  9. CW carrier xtal was changed such that CW is on same sideband as used on different bands, only 40m is now different. It is now possible to call a stn in CW and listen in cw mode - to LSB on 80, USB on the other bands. Unmodified the receiver in only in accordance for 40m LSB. This is now lost.

  10. calibrator modified according to CQ-DL (or QRV?) note described for FT-250 to avoid intermodulation on 40m.

  11. Squelch for CW/SSB for use on calling channel (432.200/144.300)
all these modifications was made in 1981-1983, so I cannot remember all

73 de jan-martin