Automatic Antenna Tuner for portable QRV
elements LC for expand band of tune ... see
lot of designs of the external automatic antenna tuners (AT)
is developed today, the part is made of them by HAMs , the most
part is made by factories (LDG, ICOM and others). The best place
for the AT installation - in a point of a antennas food, without
feedline. This reduces or eliminates
SWR losses in the coax transmission line, what is very important
for save good efficiency of antennas
If you want QRV from field
conditions and you use narrow-band antennas - you will be have
problem with high SWR, because narrow band antennas in field
conditions with non-optimal height need compensation of reactance.
introduce my new design ! This is Smart
Automatic Antenna Tuner
has been designed at 2012 year.
Specifications of this Smart Automatic
Inductance range: 0-3,75
µH in 16 steps (0-7,75
µH with additional LC
Capacitance range: 0-310
pF in 64 steps (0-630 pF with additional
L, shunt C (all switchable) - 2048 steps
Tuning times (typical): 12-15
seconds for tuning; 1 seconds to re-tune from memory
Max power: 100
W peak, 10 W in time of tuning
Frequency range: 3,5*
to 30 MHz (*- 3,5 MHz with pre-tune antenna)
Supply voltage and current drain:
via RF feed line (injector) 11 to 14 VDC
, current drain (only in time of tuning) - to 100mA (peak 2A
average 1mcek), latching relays consume no current after tuning
The actual tuning operation
is controlled by detectors (VD1,VD2 and VD3) at the measuring
bridge to the matching network. These detectors provide information
of the condition SWR to Microcontroller (Atmega 16), which adjusts
the L-matching-network constants to achieve the required match.
To conserve primary power (important for portable operations)
, latching relays are used throughout the tuner for L-matching-network.
injector is necessary for inject DC onto the coax between tranceiver
and automatic tuner.
this AT saves low SWR for your TX in all automatic tuning cycles!
The Microcontroller sets
up successive L/C combinations in accordance with a matching
algorithm, without measure frequency of the RF signal applied
to the input bridge. Finding lowest SWR. Microcontroller not
have any information from CAT system and is absolute independent.
This AT has five (8
in new AT)"antenna-memory" bank and matching
time - about 10-15 sec. AT tunes in CW mode .
Tuning cycle is very
fast if configuration is stored in EEPROM memory of microcontroller.
First time microcontroller will be "learn" for new
antenna in every band.
The AT has been enclosed
in a weatherproof, high-impact plastic housing for installation
to the antenna feedpoint. This
reduces or eliminates SWR losses in the coax transmission line,
what is very important for save good efficiency of antennas
If you need capacitors
for L-matching-network with value 1:2:4:8 (10pf 20pf 40pf
- you can made its very easy. You must take high frequency laminates
with dielectric constant above 7-8 (better 10, from Rogers corp.
or other ) and make small size capacitors.
If you want use this AT for
balance antennas - it is strongly recommended a 1:1 CURRENT
balun is included to INPUT of AT
( between AT and Antenna).
Home made capasitor ...... for example
Click for full
Modification circuit of Injector for use
with ALC and PTT remoute :
Click for download AutoTuner description
Top of Tuner`s PCB
Bottom of Tuner`s PCB
MCU Atmega 16
Bottom of PCB
Top of PCB MCU Atmega 16
Frequently Asked Question(s)
1. How can i check circuit
of tuner ? Here many wires, relay ... That easy
! Here you are -
HEX file for test circuit
After start - all capasitors
and inductor will be turned on .
elements LC for expand band of tune for 3,5 MHz and 7 Mhz
can easy add new LC elements. You need only inductance 4 uH
and capacitor 320 pF. Inductance must have good quality and
capacitor must have enough reactive power. I used ferrite
toroid (m=50) and old mica
you also must add 4 keys by BC546 for pin # 7,6,5,4 of port
Will be good
if you use ferrite beads or tubes, which employ for the dissipation
of high frequency currents in wire from keys.
New elements has been added
from above on Top of Tuner`s PCB
Keys has been
added from above on Bottom of PCB
HEX file v
8 for Flash and EEPROM memory of Atmega16
(ver 8) 8 memory bank,
sound indicator "S" in CW code with SWR>3 , support
0-7,75 µH in 16 steps + additional
few steps for new L element
Capacitance range: 0-630
pF in 64 steps + additional few steps for new C element