[ICOM] 756 ProII low power

[GGLL]

	Hello Paul, is there a definite frequency over 10 MHZ where your output 
power becomes 50 watts (I mean, abruptly) or it turns down slowly as you 
rise frequency?.

Regards
Guillermo - LU8EYW.

Paul Ferguson wrote:
> Thanks for the suggestions. 
> 
> I am using the supplied Icom cable (about 9 ft long) and my power supply is an 
> Astron 35M. It has been working fine for several years.
> 
> I removed the 756ProII top and made some measurements. Here all the voltage 
> measurements from the power supply to inside the transceiver made transmitting 
> on 24 mHz, where power output is only about 50 watts. The two voltage readings 
> for each point are at idle current then at key down:
> 
> At the power supply output lugs:  13.74, 13.72
> 
> At input (power supply side) of the fuses:  13.66, 13.35
> 
> At output of the fuses:  13.64, 13.28
> 
> At the circuit board inside the transceiver:  13.62, 13.14 
> 
> Power Supply current goes from about 3.5A at idle to 16A at transmit on 24mHz.
>  
> 
> When I transmit on 10 mHz or lower, power output is 100+ watts. Power Supply 
> current goes from about 3.5A at idle to 21A at transmit. Measuring inside the 
> transceiver the voltage is 13.62 at idle, and 12.97 at transmit.
> 
> I am getting a voltage drop between the power supply and inside the transceiver 
> of 0.6 to 0.75 volts. Would this amount of voltage drop cause the transceiver 
> to have problems generating full power out above 10 mHz?
> 
> I inspected the cable, pins, fuses and did not see a problem. I also tried 
> wiggling all connections while making measurements, but could not see changes.
> 
> 73,
> Paul
> K5ESW
> 
>> Paul: It does little if any good to measure your power supply voltage at the PS
>> end of the cable. You also do not mention if you are using the oridinal Icom
>> power cable which can sometimes drop a lot of voltage not only in the cable but
>> in the series fuses as well. Rhis is why the Icom PS-125 uses very short power
>> leads with no series fuses in the power leads. I know it is a pain to slip back
>> the boot covering the end power connector at the rig, and measure the voltage
>> there or remove the top cover and measure the voltage at the back inside of the
>> radio.To not do this first is like replacing Ohms law with Voodoo.73, Larry
>> K4LXV. ---- Your Moderator: Dick Flanagan K7VC: icom-owner at mailman.qth.net Icom
>> Users Net: Sundays, 1700Z, 14.316 MHz Icom FAQ: http://www.qsl.net/icom/
> 
> 
> ----
> Your Moderator: Dick Flanagan K7VC: icom-owner at mailman.qth.net
> Icom Users Net: Sundays, 1700Z, 14.316 MHz
> Icom FAQ: http://www.qsl.net/icom/
> 
>