I have been thinking of getting an amplifier for HF and 6m for a while but didn’t want to have 2 extra amplifiers in the shack, one for HF and one for 6m (50MHz). There are a few options about for a combined HF + 6m amplifier and luckily a Yaesu VL-1000 Quadra (1KW HF and 500w on 6m) recently came available second hand at Martin Lynch and Sons so while standing out in the single spot in the garden at the Arran DX site where I could get decent and reliable Vodafone coverage I gave them a call, agreed a price and had it shipped, bullseye!
The Quadra needs to switch bands for bandpass switching which can be achieved by sniffing RF from the exciter or via Yeasu’s 4 bit Band Data interface which most Yaesu radios support. However my exciter is an Icom IC-756pro3 and Icom do external band switching by varying a voltage on a single pin between 0v and 8v depending upon the band selected (note WARC bands are not individually identified), I could also use the CI-V frequency data (with CI-V Transceive set to ON):
L = Low / 0v, H = High / 5v
So what I need to do is build an interface which takes the Icom Band Voltage from the Icom IC-756pro3 ACC2 port and converts it to Yaesu 4 bit Band Data. If I wanted to use just CI-V I could use a PICAXE-08M (8 PIN) which support 4 output pins, Yaesu Band A to D and one serial in PIN used for CI-V but the SERIN support for the 08M is limited. I decided to go for a PICAXE-20X2 as it has a hardware serial pin, supports 19200 baud, the fastest the IC-756pro3 manages and gave me plenty of spare pins. My final spec sheet was:
- Auto switching between CI-V and Icom analogue band data as source input.
- 4 pins outputting Yaesu Band Data to the Quadra VL-1000.
- 8 additional user configurable pins, i.e. selected pin go high on selected band to drive external equipment like coax relays.
- Support remote (on/off) switching of the Quadra VL-1000 by providing 13.8v to the Quadra when the IC-756pro3 is switched on.
- Have the PTT line integrated within the interface connections, it is not connected nor needed for the PIC.
NOTE: I found the VL-1000 manual is close to useless with regards to the Pinout diagrams – it has a picture with pins numbered but has a list next to it in in letters A,B,C etc… I also blew the 5A fuse inside my IC-756pro3 and damaged a track later on by not getting the 13.8v on the correct pin, i.e. following the manual so be warned.
The PICAXE code:
Download the code, schematics and PCB layout here.
The code is split into 2 sections based on whether the CI-V is connected. If the CI-V is connected by default it is high which can be detected by the PIC which is what the line in the code equalling ‘IF CIVinPIN = 1 or CIVorADC = 0 then’ does. If there is CI-V then the PICAXE runs the CI-V routine to decode the frequency and works out the MHZ and 100KHz, i.e 14.123MHz becomes decimal 141. If there is no CI-V connected (the CI-V input to the PICAXE chip will be 0v) then the PICAXE uses a routine to look at the band data voltage using ADC to determine the band, first you need to make sure you don’t put more than 5v into the PIC, so you divide it with a couple of resistors R1/R2 so the voltage is 0.6 that of its original (i.e. 8v becomes 4.8v to the PIC). You then simply read the voltage as a function of ADC, 4.8v is 96% of 5v (we are using READADC10 which is 10bit value and the max ADC value is therefore 1024) so 4.8v = 96% of 1024 the [max] ADC value is 983. All we now do is for each band give a lower and upper limit for each ADC value (accounting for rig variance) and if the ADC value falls within a range then the appropriate band is chosen and BCD pins set accordingly.
If the band voltage is say 6.2v out the radio what band are we on? Reduced first by R1/R2 the voltage becomes 3.72v into the PIC, this has an ADC value (3.72/5v * 1024) of about 762 which rightly falls into the 80m band range. 80m has a lower ADC limit of 700 and an upper ADC limit of 799.
Remember the PIC code is split in 2, the top half is for CI-V decoding and the bottom half band voltage decoding.
When the radio is switched on 13.8v is taken from ACC2 on the IC-756pro3 which powers the PICAXE and also goes to the VL-1000 to switch it on, ensure the remote switch on the back of the VL-1000 is set to ON.
23/07/11 – Version 1.1 released:
- Improved CI-V string searching
- Additional checks in Band Data routine to ensure we didn’t get there by mistake
07/08/14 – Version 1.2 released:
- Update to schematic, R3 added on CI-V input
Code now works fine with HRD controlling the radio over CI-V and all band switching works independent of whether the radio or HRD initiates a band switch.
17/07/11 – I received an email from Jack Brindle, W6FB who commented “There is one change I would suggest in the output table, though. The BCD code 0x0 is not defined, but is used by some manufacturers. For example Elecraft uses it in the K3 for 60 meters. However, 0xF (all ones) _is_ defined as a no-band selector.” So with that in mind I’ve changed the code so ‘no band selected’ is now all 1’s (0xF) – which turns out to be 70MHz, see my post about that.
15/07/11- I received a comment from Barry GM3YEH who uses the Icom to Yaesu BCD Band Data Converter on his radio with N1MM contest logging software and a 5B4AGN BPF and found the rig stays in sync with N1MM software but the BPF only changes to the correct band temporarily then drops into a ‘no band selected’ state after a second or two. Barry suggested it might be down to N1MM polling the radio which the interface sees as 0v on the CI-V line which makes the code execute the Band Data Voltage code for which there is no band voltage data so it defaults to 0, ‘no band selected’. On 230711 I reworked the code so it now has a much better CI-V ‘search’ string so it doesn’t get false values and also added an extra check in the Band Voltage code as there were times, as mentioned above, that the code would move there even if it was receiving CI-V data.
11/03/13 – HB9LF provided a schematic version using an 74HC42 binary to decimal chip wired in parallel with the Yaesu BCD lines to give an ouput signal per band.
01/06/14 – VE7FM Steve told me he needed to swap pins 7 and 1 on the DB15(Band data 2) connector, I’ll need to open my unit to confirm but be aware.
Here are some images of the Mk2 version, which needs it’s own page when I get time…