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Author Topic: Hooking Up The Yaesu 840 To An Amp;  (Read 3476 times)

Posts: 628

« on: January 05, 2003, 01:20:41 AM »

I’ve read recently that some seem to be having problems hooking up the Yaesu 840 rig to their amp and wanted to list several possible options to accomplish this and to open this up for additional discussion. This only addresses the hookup needed to trigger the amp. Coax and ALC are not discussed.

Most rigs have available a jack known as (TX GND) or (RELAY) connected to an internal switching device for control of external devices. The relay provides a mechanical closure to ground on transmit to trigger the amplifier. On the 840, this feature is only
accessed through the band data jack using an 8 pin mini plug. So how does one hook up the 840 to an amplifier? Here are the several ways that I know of:

1) (Hook Up To A Yaesu Amp) For Yaesu amps use their cable to plug into the band data jack on the back of the 840 that’s designed specifically for the FL-7000 or later model Yaesu amps. The 8 pin mini plug goes into the back of the 840 using the band data jack and utilizes connector pin outs, #2-TX GND and #8-LINEAR and the amp is triggered no problem.

2) (Hook Up To A Non Yaesu Amp Without Interface Device) After some research it appears that to hook up without an interface, you use a modified cable with an 8 pin mini plug that plugs into the band data jack on the 840 and on the amp side an RCA plug that goes to the relay slot. The owners manual says, “you need to match the band data control lines coming from the 840 to the non Yaesu amp”. It seems to me all you need to do is to solder the connector pin on the 8 pin mini plug that matches the #2-TX GND on the band data jack on the 840 and then connect it to the amp using an RCA plug. Question, is this doable?

2) (Hook Up To A Non Yaesu Amp With Interface Device First Option) You can use an interface such as the Yaesu FRB-757. One the amp side, connect the FRB-757 to an RCA cable and run it to the relay slot on the amp. On the rig side the FRB-757 has two lines (both RCA cables), one marked red for power which you hook up to the 13.5v jack and the other marked blue to the PTT (push to talk) jack on the 840.Question: Does Yaesu still sell the FRB-757?

3) (Hook Up To A Non Yaesu Amp With Interface Device Second Option) The final option is to purchase the Ameritron interface, ARB-702(Y). The ARB-704 works with most amplifiers. Apparently, to get this unit to work with the 840 you need to purchase the PNP-8M cable also sold by Ameritron. This cable has a 5 pin mini plug that plugs into the multi-port on the front of the ARB-704 unit with the other end consisting of a 8 pin mini plug that is connected to the band data jack on the 840. The ARB-704’s power and radio jack is not used in this situation.


Posts: 1

« Reply #1 on: January 08, 2003, 02:00:08 AM »

I would try contacting N5NJ at:

His small home based company is called Competitive Cables, and he makes amplifier interfaces for Yaesu radios.  I used one of his FT-847 interface cables, and even though his web site doesn't list it i know he makes them for the FT-840, i've seen him selling them on classifieds and on Ebay.  Drop him an email and maybe that will help you out.



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