[AMRadio] Tech info for some mow dern stuff.

CL in NC mjcal77 at yahoo.com
Tue Aug 1 22:05:50 EDT 2017

Passing this along from K4MQG in case you have something modern along with your vintage.  de W4MEC    

Text follows:

HI all,

I just finished repairing a new IC-7600 radio for a customer.

When you want to attach an external device so you can run an amplifier; RTTY; or other Digital modes, you need to know that,

Icom; Yaesu; and probably Kenwood have run A+ to one pin (Icom pin 7) on the DIN ACC1 jack on the back of your radio.

A+ is defined as the 13.8VDC at its full 20+ amp level.

When this pin is accidentally shorted then the full 20 amp power supply current will find its way back to your power supply

Burning up the small traces and components along the way. I have had this happen to Yaesu radios recently.

Fortunately in the IC-7600 they designed in a 5 amp blade fuse supplying low level circuit current,

However; that 5 amp level still burned up SMT components and Printed board traces along the way, heading back to the power supply

Or in this case back to the 5 amp fuse first.

The manufacturer should have protected that A+ (back at the connector) at a much safer level of current, so it would not burn things up

When it is shorted.

The moral is: think through several times every wire you plan to hook up to your radio before you hook them up.

Mistakes will be costly now or down the road.

This also applies to putting the wrong microphone on your radio because they run voltages out onto a mic pin these days.

Of course Yaesu; Kenwood; ICOM; all use different pins on the same connector. Groan! :(

A word to the wise. HI 73’s 

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