Bitx is an easily assembled ssb transceiver for all bands and for the Amateur Radio Operator-Hams, with very clean
performance.Hams can home-brew the QRP TCVR by Using ordinary electronic components.
A new video of Bitx3B is being shown here, which has the following improvement:
1. Full coverage of 20Mt band from 14.000MHZ to 14.350MHZ
2. Zero drift with varicap tuning diode.
The varicap is 1SV149 . They work up to a maximum of 10V biasing and capable of a C max of 500pF at 1V bias. so we can manage from 8V regulator easily.
This device was suggested to me by my good friend MVS Sarma from Hyderabad. India.
After trying this device i did not think twice by replacing it with MV209.
So now we have a very stable VFO with BITX3B giving a complete band coverage, who wants a DDS anyway for a mono band tcvr ........
VIDEO OF BITX 3B FULL COVERAGE WITH STABLE VFO WITH NO DRIFT
Many friends had requested me to show how the Bitx VFO could be connected to the Ik3OIl FLL counter to stop the drift in the Bitx VFO.
Presented here is a video and details as how to connect the Bitx VFO with the Ik3OIL freq counter.
First we present the video with the Bitx VFO that is connected with the Ik3OIL Freq counter.
The FLL control circuit works with combination of some components and software on the counter and some parts are on the IK3OIL VFO pcb. The main part being the BB204 varactor diode. A buffer stage has been taken from the Ik3OIL VFO pcb.
In this demo we powered the bitx VFO and the Ik3OIL Counter . You may observe that after the red led stops to blink the FLL takes control and stabilizes the VFO.
In the demo i have also rotated the main tune and fine tune capacitor which gives complete coverage for the 20mt band. There is no drift as the tuning is stopped and the FLL control takes the new readout and starts to control the VFO.
This demo has been done on the Bitx version 3 exciter.
I would welcome any one who wants any more help.
BITX VER 3 WITH Ik3OIL FLL CONNECTED
IK3 OIL VFO PCB USED WITH THE SET UP
BITX VERSION 3 EXCITER PCB
FLL FREQUENCY COUNTER
Some important points to be noted:
In VFO use Polystyrene Or NPO capacitors
Use RG174u for all RF connections
12 Volts can be taken to the FLL VFO pcb from the bitx power supply
Bitx3B VFO stage picture has been posted here. The Bitx3B VFO is made with two number's of
T37-6 stacked together and quick fix applied on it.
The trimmer at control of FLL will need to be engaged at such a point as to observe the least drift .
The VFO is rock solid and i did not find any drift .
The FLL menu switch has been soldered on the solder side of PCB, so that it could be easier pressing the switch while adjusting the BFO or VFO to set their frequencies.