Different CTCSS tones for TX and RX

Modified on Tue, 27 Sep 2022 at 11:04 AM

Different CTCSS tones for Tx and Rx
The FTM-400 cannot do different tones for CTCSS Tx and Rx.

January 2019.. although I am sure we have done this repeatedly... now it is documented. I tried everything I could think of to get this radio to accept two different CTCSS frequencies. What I found:

1) There is only one CTCSS frequency field in the menu of the radio (Setup | Signaling | 1:Tone Sql Freq). When that changes, the tone frequency used by the channel changes (although it is not saved unless you resave the memory channel). With Sql set to T-TRX, (which stands for Tone-Tone receive... the first one indicates transmit) the one CTCSS frequency is used for both parts of the function. I verified this using another radio on the same frequency and transmitting the tone to the FTM-400 (TRX part of the function) and transmitting with the FTM-400 (T part of the function). The other radio allowed the audio of the signal to pass only if the CTCSS was set to the same value as that found under Setup | Signaling | Tone Sql Freq on the face of the radio or CTCSS value in the programmer. Then I transmitted with the other radio to the FTM-400. The FTM-400 allowed the audio of the signal to pass only if the CTCSS frequency was set to the value found in the Tone Sql Freq option (CTCSS in the programmer). Notice, the transmit and receive functions point to the same option in the radio. That option can be set only once for a given frequency.

2) Not being satisfied with what I learned; I tried some other "tricks" that I know from working with Yaesu radios for more than 25 years. In the last run of Yaesu radios that do different tones on Tx and Rx, the memory channel had to be entered as a Split even if it had a standard offset. So, I tried this with the FTM-400. Remember, all of this is being done from the face of the radio. Nothing fancy that the programmer is or is not setting. If I find something can be done from the radio's face, we will see that the programmer is setting the same options the same way. The programmer reflects the radio. It cannot make the radio do something that is not designed to do. So, I proceeded to enter a split channel. Following the steps on page 68-69, I entered a split pair thinking that I could maybe enter the CTCSS tone separately for the TX frequency. I became suspicious when the manual said, "Separate frequencies for transmit and receive...." . It said nothing about other details for that transmit frequency... and for good reason. The only thing I could entered separately was the frequency. I had set T-TRX on the first frequency entered for this channel (the receive frequency) and was not offered that option when entering the Tx frequency. When I operated on that channel, the radio responded to the one CTCSS frequency I had set originally for both the TX and RX signal. When I changed the CTCSS frequency for the memory channel, performance became based on that one new value for both Tx and Rx. As an ultimate test for this, I changed channels and changed back to this memory channel and the original CTCSS frequency was reinstated.

3) Not to be outdone, I decided to try the process described in the manual for the FT-7900 and used by many Yaesu radios in the past for programming a split channel. Although this is not documented in the manual for the FTM-400, it could turn out to be an undocumented feature that would be great to have. In this process, you program the receive frequency with its tone mode and CTCSS frequency into memory. Then you return to VFO and set up the Tx frequency with its tone mode and CTCSS frequency. Then when you press the MW key to enter memory write, select the same channel as that into which you programmed the receive frequency. Then in the final step of the process, you press the PTT before pressing the MW key to confirm the save. In other radios, this saved the Tx frequency with all its characteristics to the same channel. In the FTM-400, this exited the process without saving. So, no go here.

I can think of no other way to try this. If you have it working on your radio, let me know. It would be great to have this feature.

Now for the work around... this is still doable!

1) Program a memory channel with the frequency of the repeater. (This is the listening frequency on which you hear the repeater). Set offset to Simplex. Set Tone mode to TSql (T-TRX). Set the CTCSS frequency.
2) Program another memory channel with the transmit frequency of the repeater (this is the frequency you use to talk on). Set offset to Simplex. Set Tone mode to Tone (T-Tx). Set the CTCSS frequency.
3) Engage Sub-Band mute (in the programmer at Settings | Radio Menu Settings | Common 2 | Audio (bottom right) | Sub Band Mute) / (On the radio at Setup | TX/Rx | Audio | Sub Band Mute)
3) Once the radio is programmed with this configuration (either from its face or from the programmer), set Band A to one of these channels and Band B to the other. Be sure you are operating on the band with the transmit channel.

When you press the PTT, the repeater will hear you. Sub Bad mute will keep you from hearing yourself back immediately and possibly getting feedback. You will be listening on one band and transmitting on the other.

Alternately... program the memory channel normally with just Tone and the transmit CTCSS frequency you have been given. The repeater will hear you and allow your signal through. Without the Rx CTCSS, you will hear signals that may not be directed to you. If it is a busy repeater, this may not be a good solution as this could be confusing for you... but it will at least get you access to the repeater.

So, now we have details of what has been tried for this and two alternatives. Any input from FTM-400 users is always appreciated, especially if you have this working differently than described.

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