[ICOM] 756 ProII low power

[Paul Ferguson]

Here is how power falls off:

3.5-10 mhz -- 110 watts  
14 mHz -- 90 watts
18 mHz -- 80 watts
21 mHz -- 60 watts
24-50 mHz -- 50 watts

73,
Paul
K5ESW


>  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/
> > 
> > 
> ----
> 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/