I did some improvements to my CG-3000 ATU. All the caps in the output part of the PI network was changed to western branded 6kV low loss ceramics from Vishay etc. See pics.
No comments
Tag: ATU
CG-3000 antenna tuner. High resolution schematic diagram
The CG-3000 is a clone of a SCG tuner. It uses a PI network for tuning. There are many schematic diagrams on the Internet. However 95% of those have so low resolution that they are not readable when you zoom in. I finally found a schematic with enough resolution to show the component values. It is the output circuit that receives the highest voltages when matching a high impedance antenna and those are the most likely to be damaged. To be proactive I changed mine to 6KV types low loss Vishay Cera Mite and TDK CC45SL3 types. Below you can find the schematic, should you need to repair your tuner.
If you need to change components in the output circuit and want quick info, all the capacitors are either 100pF or 50pF ceramic. There are series and combinations of from right to left 4x100pF par, 2x100pF par, 2 x 50pF par, 2 x 100pF ser, 2 x 50pF ser. This gives the values 400pF, 200pF, 100pF, 50pF and 25pF. The relays can then switch in several combinations from 25pF to 775pF. Note that the schematic does not show that the 100pF cap is two 50pF in parallel, that the 50pF is two 100pF in series, that the 25pF is two 50pF in series. I may have an older or newer hw version than the schematic.
CG 3000 remote antenna tuner, control box (CTU) schematic
To use the CG 3000 antenna tuner for remote operation there is a control box (CTU) that could be purchased from the manufacturer. Some people want to make such a control box themselves. Here is the schematic info.
Thanks to https://sp5kab.pl/pl/sterownik-cg-3000-cg-antenna-tuner-control-unit for doing the work with determining the schematic
SGC antenna tuner info (including antenna examples and schematics)
SGC has made an automatic antenna tuner that has several smart ideas implemented. It uses a phase detector to be able to know if the load is capacitive or inductive. The design uses a RF mixer and several clever multifilar transformers. SGC also included several practical antenna antenna ideas in their manuals. I have uploaded the information here. Credit: SGC
Manual 1 PDF1
Manual 2 PDF2
Manual 3 PDF3
Icom AH-4 remote interfacing info
K9EQ made a good description of the Icom AH-4 antenna tuner including the signalling interface from the radio to the tuner and from the tuner and back to the radio. I did take the liberty to post the pdf here. Credit: K9EQ
AH-4_Design_and_OperationHow to tune a T-match antenna tuner
This article describes how to get the most out of your T-match antenna tuner. If tuned incorrectly, this type of tuner can give a lot of loss and the swr still looks ok from the shack.
Icom tuning / ATU controls
Icom Tune Control Plug – – Credit goes to KC2WI
According to KC2WI: An easy way to put most Icom radios into 10W CW for adjusting a manual tuner is with a tune control plug. All you need to make one is a pushbutton, 10K* resistor, and 4-pin Molex connector.** Connect the 10K resistor between pins 2 & 3, and the pushbutton between pins 1 & 4.
If you add a SPST switch in series with the resistor, you can switch the radio between using or bypassing the internal tuner without having to disconnect the tune controller.
My IC-746pro will switch between internal and external tuner without power cycling the radio. When you switch the “external” tuner in, the internal tuner is bypassed, but it remembers the last setting. So you could have an antenna that is resonant at one frequency, matchable with the internal tuner on another, and matchable with an external manual transmatch on another. If your transmatch has a bypass position, you could rapidly switch between 3 different frequencies/bands without ever having to actually retune.
This may also work on some other Icoms. However, my 706 will not recognize that a “tuner” is connected unless it is connected when the radio is powered on. I haven’t tried it on other radios. See note below for the IC-7000***.
diagram created using Kunky Schematic Drawing
| Molex connector: | |
| Radio Shack: | RS 274-224 |
| DigiKey: | Connector: WM1326-ND Molex 03-09-2042 Connector Plug Housing, 4-pin Pins for Connector: WM1100-ND Molex 02-09-2103 |
*For this simple pushbutton circuit you can also modify a male computer internal power connector (from a hard drive, CD drive, power extender cable, etc.). The pin spacing is identical but the keying of the housing is different. Just snip off some of the plastic from the housing so the connector fits on the radio. It won’t have the proper keying but it doesn’t matter because the connections are symmetrical.*** So you can basically make the whole thing from junk box parts.
**Other schematics show 47K or 100K.
***IC-7000 Caution: There has been some discussion about differences between the IC-7000 and other radios, and possible dangers of using tune controls designed for other Icoms on the 7000. One main issue appears to be that improper loading of or voltage on pin 1 will cause a malfunction of the fan control circuit leading to overheating. Note that pin 1 in the circuit above is open except during the tune activation. There is also a caution that connecting pin 2 to 12V is a problem because pin 2 has snubber diodes connected to the 5V bus. See the thread at groups.yahoo.com/group/ic7000/message/30151. AD5X presents an alternate circuit which incorporates a zener diode between pin 2 and 4 to limit the voltage (seewww.ad5x.com/images/Articles/TuningIntfc706.pdf). If you build the circuit with the diode note that having a proper keyed connector becomes important. If you use it with tthe SPST int-ext switch I would put the diode between pin 4 and the switch end of the resistor rather htan direct to pin 2. Steve W3AHL has made some measurements on the IC-7000 which suggest that the resistor should be a higher value than 10K. AD5X uses 47K.
.
Icom Autotuner Connector pinout:
Pin 1 is the KEY pin, when the ‘TUNE’ button is pressed, it’s pulled low by the tuner to tell the radio to start transmitting. This is the green wire on the AH-4 cable.
Pin 2 is the START pin to/from the microprocessor. Under normal circumstances the START pin is pulled high when a remote tuner is attached to tell the radio that the tuner is present. When you press ‘TUNE’ the radio pulls the pin low telling the tuner to start the matching sequence. This is the white wire on the AH-4 cable.
Pin 3 is POWER rated for 1 amp max and switches on and off with the radio. This is the red wire on the AH-4 cable.
Pin 4 is ground. This is the black wire on the AH-4 cable.
Additional Information and References:
Manual controller AT-140 but should work for AH-4
Original pushbutton circuit – pictorial diagram at http://www.hampedia.net/icom/ic-718-tune-controller-mod.php
Simple timer circuit info: http://www.hampedia.net/icom/ic-706-10-watt-tune-modification-an-icom-ic706-tune-trigger.php
Info on KG6MVB and AB2CT timer circuits: www.qsl.net/kg6mvb/tuner.html
Credit goes to KC2WI for this info. Use at your OWN risk.
Why you should choose a lowpass configuration on your L antenna tuner
K6JCA has analyzed the needed components values for matching a load while moving on a constant reflection coefficient circle. The plot below shows that in case you select the high-pass configuration for your tuner, certain angles of the reflection coefficient will give you skyrocketing component values.
Component values for the highpass and lowpass configurations
Above you can see that the LsCp &CpLs configuration keeps the max component values quite flat. LsCp and CpLS are therefore the best engineering choices based on cost and realistic component values.
http://k6jca.blogspot.no/2015/04/notes-on-antenna-tuners-t-network-part-1.html