Outdoor External Speakers for Kenwood TK-7180

[SpectralContent]

I am setting up a Kenwood TK-7180 to be used as a railroad radio scanner at a Train Viewing Platform and am looking to figure out an external speaker setup that will allow me to route various speakers around the inside of a covered pavilion. I am wondering if anyone is aware of the operation requirements that the TK-7180 has in order to power a speaker without external power and/or if anyone has a recommended setup they have used on similar outdoor scanner speaker systems. Ideally, I would like to have two speakers. If anyone knows of a way to make this work, your thoughts would be greatly appreciated. Thanks!

 

[mmckenna]

Two options that pop to mind….

The TK-7180 has the KAP-2 optional connector. This is designed for connecting the KES-5 external speaker. With that, you can pipe audio out of the radio, or use it as a Public Address system.
It's really only designed for running one KES-5 speaker, so it might not have enough kick for what you want.

Other option is to take the filtered audio output off the rear 25 pin DSUB connector and use that to feed an external amplifier. Of course the external amplifier is going to need power, but you can find 12 volt powered amps that will feed a couple of speakers, that amp could be powered off the same power supply as your radio.

 

[SpectralContent]

Other option is to take the filtered audio output off the rear 25 pin DSUB connector and use that to feed an external amplifier.

As I'm still familairizing myself with the TK-7180, is the DSUB connector a direct audio output? Ie. If i where to get a DSUB to 3.5mm jack converter I would be able to hear audio directly from the connection without any digital signal parsing? I was under the impression that the DSUB signal contained more information-bearing signals (ie Alpha tag info and whatnot) than just audio alone. I'm probably wrong in that regard though.

 

[mmckenna]

On the rear 25 pin DSUB connector:
Pin 17 = AFO Received Filtered Audio Output DC coupled, AF low level output 700 mVpp typical while receiving standard modulated signal.
Pin 7 = Ground

This will give you essentially an analog line level output that you can use to feed an audio amplifier. There's a lot of pins and signals available on the 25 pin connector, but Pin 7 and 17 are all you need.

 

[KK6ZTE]

The DB25 won't provide enough oomph to drive a speaker. The KAP-2 will, however. I have a TK-8180 at a hospital driving two 8 ohm speakers in parallel (Motorola HSN8145BA in this case) (don't get me started, they didn't need it, but whatever...) to enable two different positions to monitor the medic radio.

You can find the KAP-2 on ebay routinely below my cost as a dealer... that's where I get them for my personal radios.

The KES-5 radio is weatherproof but a 4 ohm speaker. The TK-7180/8180 can provide 4 watts at 4 ohms. Most speakers available (including the Roadpro P.O.S. that Kenwood replaced the KES-3(S) with), are 8 ohms and can be safely paralleled.

 

[chief21]

If there is any way that you can use an inexpensive, outboard PA / audio amplifier for this setup, that should be preferred. Assuming proper installation, the separate amplifier will give you better control of the audio, the potential for more speakers / better volume, and better protect the source equipment.

 

[kd4efm]

for the DB25, it is low level output, so you need a transformer at 100K to 600 ohm unbalanced.
to the external pa system.


External Speaker jack, just make sure you have an 8 ohm tap or transformer (8 ohm to 600 ohm unbalanced) then you can use a p.a. system with ability to have several speakers off of it,

 

[westcoaster]

Here is an example of a paging system being discussed here.
60 watt amplifier with three or four 70Volt outside paging horns tapped at 1.5 to 5 watts (with 70V paging it is better to adjust the volume at the individual speakers rather than at the amplifier. It is also better to place the speakers at the point of greatest noise (beside the railroad tracks) and let the sound from the speakers carry with the sound of the train rather than trying to fight against)

Remember, this is an example: for what you want to do and the type of equipment you are after.

https://www.bogen.com/products/pdfs/telephonepagepdfs/TPU35Bs.pdf

Inputs:
TEL: 600-ohm balanced line, transformer-isolated
MUSIC: Hi-Z source, RCA jacks or screw terminals
MIC: Lo-Z balanced, screw terminal connection (dynamic only)
MUSIC MUTE: Mutes music when shorted
CONTACT RING: Sounds night ringer tone when customer-supplied dry contacts are closed
TEL RING: Sounds night ringer in response to 90V ring signal
BRIDGING: Permits bridging of two amplifiers

Outputs: 25V, 25VCT, and 70V, 16 ohms balanced or unbalanced for 35/60/100-watt models; 25V and 70V for TPU250.
Provision for WMT1A line-matching transformer