TEST WITH UNMODIFIED FL-110 (5 W drive and 13.8 VDC)
13.8 VDC
160 m
80 m
40 m
30 m
(20m LPF)
20 m
17 m
(15m LPF)
15 m
12m
(10 m LPF)
10 m
Output
60 W
70 W
80 W
105 W
105 W
60 W
80 W
60 W
55 W
G4EDG's ADVICE
I completed the mod suggested by Frits, PA0FRI and indeed the power required to drive the FL-110 to 100 W output is now in the region of 5 W.
Just a word of warning when uses this amplifier with a FT-817. Used in the RF detection change over mode, this set-up lasted about 5 min before the '817 PA module blew!
I guess the change over time of the amplifier relay was enough to leave the '817 output unterminated, and with no effective high SWR protection in the 817, caused the PA
to fail.
This is in no way due to PA0FRI's mod, but would suggest using hard switching from the 817 accessory connector to provide T/R switching for the amp.
73 Steve G4EDG
RELAY STEP-UP OR SPEED-UP FOR DECREASING PULL-IN TIME
This in many magazines published simple design for increasing the relay pull-in time is often
overlooked. This circuit works by using a short burst of a double supply voltage to move the
contacts and then applies the original volts to the relay to lock the contacts in place.
On receive the capacitor is charged to the supply voltage through both diodes. When switch (PTT) is
pushed, the transistor turns on through 1 kΩ by the charged capacitor. Then the relay momentarily
is supplied with about twice its voltage and closes faster than normal without harming the coil.
As soon as the capacitor discharges, the relay coil sees a normal supply voltage.
When the LPF PCB is folded up, on the lower print one see a red-white wire from an upright pin to the relay. The
wire is disconnected and solder to the relay accelerator. Then, according to the diagram (fig»), connect junction
point of elco and diode to pin; further connected circuit to ground.
In summary, the relay accelerator is connected to:
1. the loosened red-white wire to the relay
2. the pin
3. mass
This shows how K1 is used as central point for the installation.
In the right image I used a SD355 transistor as universal type, but you can use a BC547.
CONTINUATION
The previously implemented modification of the amplifier applies to the FL-110 at that time available to me. Meanwhile, it has been turned out that schematic and assembly
of a FL-110 have undergone factory changes. An example of this is shown in the following image, but it is not excluded that there are more changes in circulation.
MODIFICATION FOR FLEX-1500
Decades ago I purchased my 2ndhand's FL-110 as spare, tested once for good operation and then no longer used. That changed when a FLEX-1500 came into my
possession. Because this SDR transceiver delivers only about 5 W ouput, the PA appeared to be suited as amplifier.
It turns out that the corresponding circuit in my unmodified FL-110 differs from the downloaded Instruction Manual FL-110.
After some experimentation, a suitable update was found by replacing the
original 33 Ohm resistance with a 6.8 Ohm induction-free type. The
obtained ouput with control from a FLEX-1500 is shown in the table. For
the WARC segments LPFs of the next higher bands are used. Remarkable
is that maximum output on 12 and 10 m were obtained with the 15 m
band low-pass filter (LPF).
See also
FL-110 Manual
,
FLEX-1500 & FL-110
