VX-5500 with RMK-4000 remote head kit?

[carry-overtone-tranquil]

Hi team,

I'm trying to set up a VX-5500 with an RMK-4000 remote head kit which I believe should just be an RMK-4000B (deck side) and RMK-4000H (control head side). I've got the kit plus a CT-81 cable. It seems like this should be all I need.

With everything connected, the radio boots and the control head works ... mostly. I can change channels and groups, and the mic works. I can program the radio through the mic connector on the remote control head. However, I can't seem to get audio out of the control head (or possibly anywhere, need an external speaker for debugging). Beeps when pressing buttons don't do anything, nor does incoming signal.

If I take the RMK-4000 out and re-attach the control head directly to the radio deck, everything works as expected again.

It seems like the RMK is more than just a passive converter to the CT-8x cables - I guess it enables the multi-deck and multi-head capability. I have the service manual for the radio itself, but that doesn't include any service information for the two boards in the RMK-4000 parts. I don't see a lot on those boards that indicates that they're configured for a specific mode that isn't single remote head, but they certainly could be.

I did continuity test the CT-81 after routing it through my vehicle, and all of the circuits appear to still be operational.

Any suggestions for how to further diagnose or get this working are appreciated!

Best,

cot

 

[carry-overtone-tranquil]

I should note that the RF Deck side (RMK-4000B) has two ports populated labelled C&D. A&B are unpopulated, and looking at the board it is definitely missing some passives to complete those ports. I wonder if the C&D ports are for enabling multi-deck use rather than multi (or single) remote head use? I guess I need a manual or some pictures of the different varieties of these things.

 

[jeepsandradios]

If I recall you need the remote speaker for that combo to work. Its been a while since I installed a VX5500 but all had external speakers front and back of the ambulances I installed.

This may have some info for you -

http://www.repeater-builder.com/yvs/pdfs/vertex-vx-5500l-service-manual-2015.pdf

http://www.repeater-builder.com/yvs/pdfs/vertex-vx-5500-operating-manual.pdf

 

[carry-overtone-tranquil]

Thanks @jeepsandradios! I'll try an external speaker next. It does seem like a strange requirement - if the front panel speaker is good enough for use on the deck, presumably it should also be good enough for use in a remote position. The user manuals have been pretty slim on details about the RMK - they list it in the optional parts list, but so far I've not found any documentation about it's installation.

 

[carry-overtone-tranquil]

Picked up an MLS-100 today, and plugged it into both the port on the RF deck as well as the port on the RMK-4000H. When plugged into the RF deck, audio came out regardless of whatever the speaker selection was set to. When plugged into the RMK-4000H, the external speaker did not produce any audio, regardless of whatever the speaker selection was set to.

This helps narrow things down a little, audio is either not making it onto the CT-8x cable from the RMK-4000B, or is not making it off the cable from the RMK-4000H. I guess scoping those two boards is the next step.