Modifications for the Yaesu
FT-7
19-07-1998 FT-7 modifications
made
- 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.
- 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
- 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.
- 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.
- Noise blanker improvement (see FT-7B circuit). An extra capacitor is
connected as for FT-7B.
- 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
- Key jack. a new 6.3mm stereo jack was installed (where remote vfo
connector was). PTT and key is connected.
- 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.
- 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.
- calibrator modified according to CQ-DL (or QRV?) note described for FT-250
to avoid intermodulation on 40m.
- 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