Kenwood TS-711 and the Piexx CAT Interface - UK Vintage Radio Repair and Restoration Discussion Forum

Superscope · 12th Dec 2022, 6:46 pm

I probably know the answer to this already, but I thought I would
put this out there.

Has anybody successfully got a Kenwood TS-711 with a Piexx CAT
interface working with one of those generic USB-Kenwood Interface Cables.

Mine works fine plugged into a genuine Serial Port, but the PC will just not
recognize the Rig using a USB Interface Cable. (Kenwood IF 232 C equivalent cable).

I'm guessing the Piexx Board (IF10 A equivalent) wants to see genuine RS 232
levels or there abouts, and doesn't like the TTL levels presented by the generic USB Cables.

Was interested if anybody can contradict the above assumption from experience.

I don't have this problem with the TS-440. The generic Kenwood Interface Cable works fine, but the
TS-440 doesn't need a Piexx Interface board and has TTL Levels as far as I understand it.

Ian

Hans PE1KWH · 16th Dec 2022, 7:57 am

Kenwood used inverted TTL levels in several radio's.
Hence the optocoupler in the IF232C interface.

Standard USB to RS232 TTL converters don't work unless followed by the optocoupler which acts as a inverter.

Superscope · 16th Dec 2022, 9:48 am

Thanks Hans,

The issue here though is not the Data inversion.
That's carried out by the Kenwood USB cable anyway.

I have spoken to Piexx and it is as I thought, a problem with Levels.

I was hoping the tolerance of their Board might be wide enough to still
work with TTL levels but a lass not. That was wishful thinking to far!

Hence why I asked if anybody had successfully used a Piexx Board with a
modern Kenwood USB interface cable.

Ironically, I now have to invert the original Kenwood Level conversion.

At least if I have no access to an RS-232 Port.

Ian

Hans PE1KWH · 16th Dec 2022, 7:07 pm

Ok i understand.
Those cables put out signal levels of about 5.5 V negative/positive and that is below the RS232 specs.

I have been working on a modern home brew replacement for the IF232C interface and ran in that problem.

Luckily a FTDI cable can be (re)programmed to invert it's signals using a little prog from the FTDI website.

I now can read/write to my Kenwood TS450S.

SiriusHardware · 19th Dec 2022, 12:41 am

I once saw a curious arrangement in a programming interface cable for a PMR radio which used two back to back sections of a MAX232 RS232-TTL-RS232 level converter interface IC. Going in either direction, the RS232 signal was being inverted and converted to TTL-level by the first MX232 section and then uninverted and converted back to RS232 level by the second MAX232 section.

Why? Why not just pass RS232 straight through?

On closer examination it was noted that the RS232 output levels from the radio were only +5V / -5V and the radio manufacturer was either concerned or had already found that those reduced levels would not be seen as valid by all host PCs.

The MAX232 ICs on the other hand are very tolerant of 'bad' RS232 input levels and use internal voltage boosters to generate an output swing of +10 / -10V on their RS232 outputs from a single +5V supply, so what the circuit was actually doing was acting as an RS232 signal conditioner or 'booster'.

Rubbish / weedy RS232 in, big, beefy RS232 out.

Superscope appears to have solved his problem (?) but anyone else suspecting they have RS232 level related problems in future could consider making a similar circuit to place between the PC USB serial interface and the RS232 interface of the radio (if, and only if, the radio actually sends and receives RS232 level serial signals and not TTL-level ones).

sidspop · 5th Jan 2023, 5:54 am

Slightly off topic, but still on it.
The PIEXX CTCSS board for the 711 is very hard to find, and very expensive if found.
An alternative is the G8TMV board. Fitting is a doddle, utilising NB switch to turn on, and Speech switch to change tone.
One interesting thing is rather than using an LED to indicate chosen tone, the CW sidetone is still active in FM mode, so output fed to CW key through an optocoupler gives a morse signal via the speaker.
Total cost about 20 quid, rather than the bingo numbers for a PIEXX or TU-5.

12th Dec 2022, 6:46 pm	#1
Superscope Octode Join Date: May 2017 Location: St Austell, Cornwall, UK. Posts: 1,018	Kenwood TS-711 and the Piexx CAT Interface I probably know the answer to this already, but I thought I would put this out there. Has anybody successfully got a Kenwood TS-711 with a Piexx CAT interface working with one of those generic USB-Kenwood Interface Cables. Mine works fine plugged into a genuine Serial Port, but the PC will just not recognize the Rig using a USB Interface Cable. (Kenwood IF 232 C equivalent cable). I'm guessing the Piexx Board (IF10 A equivalent) wants to see genuine RS 232 levels or there abouts, and doesn't like the TTL levels presented by the generic USB Cables. Was interested if anybody can contradict the above assumption from experience. I don't have this problem with the TS-440. The generic Kenwood Interface Cable works fine, but the TS-440 doesn't need a Piexx Interface board and has TTL Levels as far as I understand it. Ian Last edited by Superscope; 12th Dec 2022 at 6:55 pm.

16th Dec 2022, 7:57 am	#2
Hans PE1KWH Triode Join Date: Jul 2016 Location: Hilversum, Netherlands Posts: 33	Re: Kenwood TS-711 and the Piexx CAT Interface Kenwood used inverted TTL levels in several radio's. Hence the optocoupler in the IF232C interface. Standard USB to RS232 TTL converters don't work unless followed by the optocoupler which acts as a inverter.

16th Dec 2022, 9:48 am	#3
Superscope Octode Join Date: May 2017 Location: St Austell, Cornwall, UK. Posts: 1,018	Re: Kenwood TS-711 and the Piexx CAT Interface Thanks Hans, The issue here though is not the Data inversion. That's carried out by the Kenwood USB cable anyway. I have spoken to Piexx and it is as I thought, a problem with Levels. I was hoping the tolerance of their Board might be wide enough to still work with TTL levels but a lass not. That was wishful thinking to far! Hence why I asked if anybody had successfully used a Piexx Board with a modern Kenwood USB interface cable. Ironically, I now have to invert the original Kenwood Level conversion. At least if I have no access to an RS-232 Port. Ian

16th Dec 2022, 7:07 pm	#4
Hans PE1KWH Triode Join Date: Jul 2016 Location: Hilversum, Netherlands Posts: 33	Re: Kenwood TS-711 and the Piexx CAT Interface Ok i understand. Those cables put out signal levels of about 5.5 V negative/positive and that is below the RS232 specs. I have been working on a modern home brew replacement for the IF232C interface and ran in that problem. Luckily a FTDI cable can be (re)programmed to invert it's signals using a little prog from the FTDI website. I now can read/write to my Kenwood TS450S.

19th Dec 2022, 12:41 am	#5
SiriusHardware Dekatron Join Date: Aug 2011 Location: Newcastle, Tyne and Wear, UK. Posts: 11,575	Re: Kenwood TS-711 and the Piexx CAT Interface I once saw a curious arrangement in a programming interface cable for a PMR radio which used two back to back sections of a MAX232 RS232-TTL-RS232 level converter interface IC. Going in either direction, the RS232 signal was being inverted and converted to TTL-level by the first MX232 section and then uninverted and converted back to RS232 level by the second MAX232 section. Why? Why not just pass RS232 straight through? On closer examination it was noted that the RS232 output levels from the radio were only +5V / -5V and the radio manufacturer was either concerned or had already found that those reduced levels would not be seen as valid by all host PCs. The MAX232 ICs on the other hand are very tolerant of 'bad' RS232 input levels and use internal voltage boosters to generate an output swing of +10 / -10V on their RS232 outputs from a single +5V supply, so what the circuit was actually doing was acting as an RS232 signal conditioner or 'booster'. Rubbish / weedy RS232 in, big, beefy RS232 out. Superscope appears to have solved his problem (?) but anyone else suspecting they have RS232 level related problems in future could consider making a similar circuit to place between the PC USB serial interface and the RS232 interface of the radio (if, and only if, the radio actually sends and receives RS232 level serial signals and not TTL-level ones).

5th Jan 2023, 5:54 am	#6
sidspop Triode Join Date: Jun 2015 Location: West Bromwich, West Midlands, UK. Posts: 42	Re: Kenwood TS-711 and the Piexx CAT Interface Slightly off topic, but still on it. The PIEXX CTCSS board for the 711 is very hard to find, and very expensive if found. An alternative is the G8TMV board. Fitting is a doddle, utilising NB switch to turn on, and Speech switch to change tone. One interesting thing is rather than using an LED to indicate chosen tone, the CW sidetone is still active in FM mode, so output fed to CW key through an optocoupler gives a morse signal via the speaker. Total cost about 20 quid, rather than the bingo numbers for a PIEXX or TU-5.