VE4WPG Output Tone Changing to 88.5 Hz

The RAM Technical Committee is changing the VE4WPG output CTCSS tone from 127.3 Hz to 88.5 Hz to mitigate an intermittent noise issue at Richardson Centre. The input tone you transmit to access the repeater remains 127.3 Hz. Depending on how your radio is currently programmed, you may need to make a small change.

This is the same configuration already in use on VE4ACX, VE4CNR and VE4GIM.

What Is Changing

	Before	After
Input tone (you transmit)	127.3 Hz	127.3 Hz, unchanged
Output tone (repeater transmits)	127.3 Hz	88.5 Hz

What You Need to Do

If you transmit 127.3 Hz and receive on carrier squelch (no tone decode today): Your transmit setting is still correct. No change is needed.

If you receive on tone squelch with 127.3 Hz decode today: Update your radio’s receive decode tone to 88.5 Hz. Leave your transmit tone at 127.3 Hz. If your radio supports split tones (separate encode and decode), program encode at 127.3 Hz and decode at 88.5 Hz.

If your radio cannot store separate transmit and receive tones: Most such radios still support tone encode only. Set your transmit to 127.3 Hz and switch your receive to carrier squelch. Having 88.5 Hz on the repeater output does not prevent carrier squelch reception. The sub-audible tone is filtered out by your radio’s audio circuits and you will not hear it.

The technical committee has updated the club CHIRP file as of May 14, 2026 with a tone-encode-only configuration for VE4WPG. Loading the current file is the simplest path to a working setup.

Why We Are Making This Change

The site at Richardson Centre is a difficult RF environment. A new FM broadcast station was approved and installed at the site within the past year, joining an existing co-located broadcaster. Other land mobile radio (LMR) systems on the roof contribute further noise and intermodulation products to the environment.

The specific issue we are addressing is intermodulation between VE4WPG’s own transmit signal and the two co-sited FM broadcast stations. The two broadcasters are spaced 600 kHz apart in frequency. Because 2 m amateur repeaters use a 600 kHz offset between input and output, a third-order intermodulation product of these three signals lands directly on the repeater’s own receive frequency.

That intermod product carries the same 127.3 Hz CTCSS tone the repeater is transmitting. The repeater’s receiver, listening for 127.3 Hz on its input, accepts the intermod as a valid signal, opens its squelch, and retransmits the noise.

By changing the repeater’s transmit tone to 88.5 Hz while leaving the input decode at 127.3 Hz, the intermod product derived from the repeater’s own signal no longer carries the tone the receiver is listening for.

For background, see also Continuous Tone-Coded Squelch System (CTCSS) on Wikipedia.

Why We Tried Filtering First

The committee installed additional filtering ahead of the VE4WPG receiver in earlier work this year. Filtering helped, but did not fully isolate the receiver from the intermod product. The broadcasters operate at high power at very close range, and the unwanted product remains strong enough to be a problem after the filtering we are able to apply.

Why Picking a Different Single Tone Would Not Help

A natural question is: why not just change VE4WPG to a different single CTCSS tone? The reason a single new tone does not fix the problem is that the intermod product always echoes back whatever tone the repeater is transmitting. If the repeater transmits 100 Hz, the intermod product carries 100 Hz, and the receiver (listening for 100 Hz to validate users) is fooled by its own intermod in exactly the same way as before.

The loop is only broken when the transmit tone differs from the input decode tone. That is what split tone gives us.

Why Swapping VE4WPG Onto Different Frequencies Would Not Help

Another natural question is whether VE4WPG could be moved onto a different frequency pair, for example by swapping with VE4WRS. The arithmetic that produces the intermod product is driven by the 600 kHz separation between the two broadcasters combined with the 600 kHz repeater offset used on the 2 m amateur band. No matter which 2 m frequency pair the repeater uses, the intermod product produced by mixing its transmit signal with the two broadcasters lands on a frequency 600 kHz away from the transmit, which is the receive frequency.

The only way to escape this relationship would be to change the repeater offset itself away from 600 kHz, which is not an option under the standard amateur 2 m band plan. Moving onto another 2 m pair simply moves the same problem to that pair, while requiring every user to reprogram.

Need Help Reprogramming?

We know radio programming is not everyone’s strong suit, and we want to make sure no one ends up off the network because of this change.

Wednesday evenings at the WSC Clubhouse: Bring your radio and, if you have it, your operating manual. Send a quick email to tech@ramb.ca ahead of time with your radio model so we know what to expect. The technical committee has programming cables for nearly all common radios and software for most.

If mobility is a barrier: Email tech@ramb.ca and we will do our best to find a volunteer to pick up your radio, get it programmed, and return it to you.

We Are Here to Help

We understand that changes like this are inconvenient, and we appreciate your patience as we work through an RF environment that is largely outside our direct control. We are a club that works together, and there are many members who want to help. If you are unsure about the programming, the concepts, or the logistics, please reach out. No question is too basic, and no one should be left off the network over a tone setting.

73, the RAM Technical Committee
tech@ramb.ca