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Author Topic: Icom 718 Digital Low Output RF Power  (Read 7893 times)
AE7VA
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Posts: 35




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« on: July 01, 2012, 12:14:00 PM »

I've switched from using my old Icom 735 to a Icom 718 for PSK-31 and MT-63.  I'm using a Rig Blaster Plug and Play connected to the ACC jack (in the same manner as my 735).  The microphone is disconnected from the microphone jack. 

The difference is that the 718 only puts out a maximum of 10 watts regardless of sound card output/increase in ALC or increase in RF power level or mic gain. 

I've checked the USB voice transmitter with a separate Daiwa meter and it will supply 100 watts no problem.  So the transmitter doesn't appear to be the problem. 

I've scoured the manual for the initial and quick settings but haven't found any settings that I need to change.

It seems like it isn't getting driven from the sound card, but when I adjust the soundcard's output I can watch the ALC meter on the 718 go from zero to full scale....obviously being driven.

Anyone else have this problem or a suggestion?
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AE7VA
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« Reply #1 on: July 01, 2012, 01:37:33 PM »

**UPDATED**
The difference is that the 718 is irregular in its power output compared to the 735 which gave solid, reliable meter readings.  When I connect the 718 to the same tuner and G5RV, 10 watts is all she'll give in PSK-31 and no more than 2 watts in MT-63.  I've altered the sound card output, RF power level, and mic gain (which should have no effect since I"m not using the mic connector.) SWR checked for 1:1 match.

I've scoured the manual for the initial and quick settings but haven't found any settings that I need to change.

It seems like it isn't getting driven from the sound card, but when I adjust the soundcard's output I can watch the ALC meter on the 718 go from zero to full scale....obviously being driven.

Maybe I'm not understanding how the 718 indicates power out.  The manual doesn't specify if the RF Power is % of 100 or some other relational number.

Here are some numbers running PSK-31 based on a stand alone Daiwa meter (PEP reading) and dummy load which also match the radio's internal RF power meter:

Set      Out (watts)
20        5
43        20
50        35
75        55
100      120 (not sure how I'm getting more than 100 here)

When running voice and doing the same check by providing a tone to the microphone, the Daiwa meter and internal meters match exactly throughout the same range however at the 100 setting the meter says that the output is 150 watts. 

I'm starting to wonder if the manual tuner is bad, maybe the electronics for the meter are bad and its throwing everything off??  Although the radio's internal meter also shows only 10 watts out regardless of RF power setting....which shouldn't be correct even if the manual tuner's meter was malfunctioning.  Tuner is showing 1:1 SWR which matches the radio's internal tuner. 
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KB3MDT
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« Reply #2 on: July 01, 2012, 06:48:01 PM »

Hi,
    Just for grins, check the following.
1) RF Power Setting.   While the Transceiver is on, press the SET button for 1 Second.   Press the Up and Down Buttons (Lower right corner of Transceiver), and check the RF Power Settings.   It should be "H" for High.
2) Mike Gain.  Same Quick Set menu system as above.  Make sure its set to 50.   I don't know if this impacts the rear connector, but suggest you check it any way. 
3) Make sure you are using the right display mode on the bar graph.  It shows ALC, SWR, and Power.  Toggle through them by using the SET button, pressing it momentarily.
4) Make sure the DIN Cable is wired properly.  I believe PIN 2 is Ground, PIN 11 (Modulator Input) should be audio In. 

I have a home brew interface between my computer and ICOM 718, using two audio transformers, two Potentiometers, and a couple of resistors.  My interface uses the Mike Connector on the front.    I use PSK-31 and other digital modes at about 30-40 watts all the time.
 
Also, a perfect 1:1 SWR reading sounds a little suspicious.   Maybe something is wrong with the tunner or antenna.    Good Luck.

KB3MDT
Ken
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NA4IT
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« Reply #3 on: July 01, 2012, 07:45:50 PM »

When you mentioned G5RV, that told me a lot. It very well may work fine with the other rig, but be putting RF feedback into the 718. Have seen it happen.
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AE7VA
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« Reply #4 on: July 03, 2012, 06:26:31 AM »

When you mentioned G5RV, that told me a lot. It very well may work fine with the other rig, but be putting RF feedback into the 718. Have seen it happen.

That might be it.  That wouldn't explain the same performance into the dummy load.

I'm going to pickup the adapter for my Kenwood TS-590S and see what results I get there.
« Last Edit: July 03, 2012, 06:28:13 AM by AE7VA » Logged
AH6RR
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Posts: 803




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« Reply #5 on: July 03, 2012, 05:47:29 PM »

The TS-590S does not need an interface to do Digital modes just use the USB Cable and choose the USB AUDIO CODEC in your software and turn on the USB Vox in the 590 and your set.
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KB6HOH
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Posts: 189




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« Reply #6 on: July 07, 2012, 02:16:15 AM »

Paul,

       I too run the Icom IC-718 and have NO problems here.
My Station is of  course the IC-718, Tigertronics Signalink USB Sound Card Interface, 230foot Delta Loop Ant.
There are NO Menu settings for running Digital on the IC-718.
Since we both use the 13pin ACC Port here are the setting I use. (No USB-D or USB-L or any of that)

1. Radio's RF Output from the Menu set at 100watts. (Signalink USB TX controls the RF Output)

2. Radio's Mic Gain level from the Menu set at zero.
(Remember to reset it for Voice ops. Also Mic is NOT disconnected when TXing from the ACC Port so Mic Gain has to be zero to avoid picking up any Back ground noise and ALC will show as none.

3. Comp and DSP functions all turned off.
(Also note to Ken KB3MDT I strongly discourage use of the Mic Jack where the ACC Jack is for this purpose)
With the above settings, my Signalink USB controls the RF Output and the Receive Gain via the TX and RX Level controls on the interface and I can run the TX Power up to 100watts or as little as possible.

4. What Sound Card program are you running, FLdigi, HRD/DM780, MultiPSK or MixW?Huh

Anyway questions drop me an Email.

                                        73 de Steve KB6HOH
                                   kb6hoh(AT)comcast(DOT)net
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KA9CCH
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Posts: 87




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« Reply #7 on: July 20, 2012, 11:11:41 AM »

I had the same symptom with my 718.  I found my 718 is very sensitive to where in the passband I was trying to transmitt.  When I was toward the ends of the waterfall the power out was low no matter what I did.  If is stay in the middle of the waterfall all is good.  So to answer a CQ I first make sure to position the signal close to the waterfall center and then all is well.  My 735 is not as picky.  Experiment a little w/ a dummy load across the displayed psk window. 

YMMV
KA9CCH
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VE3FMC
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« Reply #8 on: July 20, 2012, 06:20:31 PM »

I had the same symptom with my 718.  I found my 718 is very sensitive to where in the passband I was trying to transmitt.  When I was toward the ends of the waterfall the power out was low no matter what I did.  If is stay in the middle of the waterfall all is good.  So to answer a CQ I first make sure to position the signal close to the waterfall center and then all is well.  My 735 is not as picky.  Experiment a little w/ a dummy load across the displayed psk window. 

YMMV
KA9CCH


My 718 acted the same way. My FT-950, not so much.
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G0GQK
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Posts: 634




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« Reply #9 on: July 23, 2012, 01:52:32 PM »

I have a 718, use an optocoupler connected to ACC1 then to the compuer and have never experienced any of the problems metioned. The rig is set for no ALC, full power and I can move around from the centre frequency with no loss of power. All my antenna's are 1:1 at the PSK frequencies but I don't think the low SWR has any effect. I suggest you check with a dummy load

Mel G0GQK
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KC7YE
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Posts: 95




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« Reply #10 on: July 24, 2012, 07:17:24 AM »

Have 718 & Tigertronics interface. When call Tigertronics to order they told me not to use the ACC, could expect trouble if did. Works for me , use indoor random wire in condo.
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