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Author Topic: Inital Power Spike IC-7300  (Read 5628 times)
KC4PX
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Posts: 11




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« on: May 12, 2017, 08:13:42 PM »

I currently use an ACOM 1500 amplifier with my IC-7300. I have set the Power Output at 34%, but on initial modulation or MSK144 I see a power Spike. Is this normal or specific to my unit? Ivars, KC4PX
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W1QJ
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Posts: 2607




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« Reply #1 on: May 13, 2017, 05:26:40 AM »

This is a problem with this radio.  One fellow who has an Alpin amp can't use the amp with a 7300, it detects the spike and the amp goes into standby fault mode.  Icom has had this problem before with several radios going back as far as the 781 I believe it was.  Nothing new here.
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ZS5WC
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« Reply #2 on: May 13, 2017, 05:28:30 AM »

 :)I don't own a 7300, but I can suggest not to use compression, Instead of lowering the drive level alone, reduce mic. gain / audio gain to only JUST achieve the required level.

73 de William
ZS4L / ZS5WC
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K7JQ
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Posts: 953




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« Reply #3 on: May 13, 2017, 06:34:00 AM »

I've used a 7300 with an Acom 1500 (since last Sept) through many contests, and haven't noticed any spikes that would affect the amp. I had two hot switch faults that I remedied by changing the TX Delay from 10 to 15ms. I drive the amp with 60-70% power from the 7300 (1,300W CW; 1,500W Peak SSB), and #2 compression on SSB...no problem. I also use two Heil dynamic mics, with audio gain control at 65-70%. If I use VOX, the VOX gain has to be around 90% for proper activation.

73, Bob K7JQ
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KM3F
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Posts: 791




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« Reply #4 on: May 13, 2017, 08:07:50 AM »

On SSB there is no RF drive until the mike picks up a sound. (the balanced modulator carrier is nulled out)
Your mike likely is picking up a sound whether a relay or some other sound the mike hears. Unless that happens there should be  no RF output to limit with the power level setting.
If you hand key a mike, their is your sound if the key is built into the mike.  I use remote silent keying.
Normally you select a delay out of menu so the system settles down before the amp is keyed.
In my case I use outboard audio processing and have Downward Expansion dialed in.
I adjust DE until there is no RF power indicated on the peak reading power meter at key up with the amplifier on line.
Works all the time.
Some will say a "peak reading" power meter will not pick up a spike but cannot be true if it registers any power generated from the mike through the radio.
Delay and or meter ballistics has no effect, it will still read a power as long as the power out is above the rated minimum for the meter and the scale.
A way to tell is key up with mike disconnected and set the Power meter in its lowest scale.
If there is any output the meter will detect it. Do this without keying the amplifier.
Of course don't do this with obvious power spikes since you can already see it happening at higher spike levels.
Bottom line is there can be several reasons for power spiking you need to recognize before a possible remedy can be tried.
If high mike gains are used and or internal speech processing is used, the audio chain will be highly sensitive to keyup spikes and background noise.
BTW, I've already read and heard all the other replies to this from ALC limiting with a battery, the system loop delay etc. I don't have any of this with a Kenwood TS 2000 driving an amplifier.
Everybody's problem is not always the same with different equipment and procedures in use.
Good luck.
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K6AER
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Posts: 4671




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« Reply #5 on: May 13, 2017, 09:02:30 AM »

Disconnect the microphone and key the radio. No RF spikes should occur. As mentioned already your compression and mic gain may be to high. On my 7300 the compression is set to 2 and the mic. gain is set to 3. You should be close talking the microphone and have the radio settings accordingly.

Also does your shack have a high noise level?  How do you see the power Spike? Are you using the ALC? The 7300 has excellent power regulation and does not need ALC.
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N6YFM
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« Reply #6 on: May 13, 2017, 04:45:29 PM »

You guys all seem to be assuming that this is an SSB thing :-)
I have an Icom 7300 for the last 12 months.   Great radio, but like
most Icom's, it does indeed create an initial higher power spike when
starting a transmission on any digital mode (non-SSB).
I can read this spike on my Wavenode digital power meter, and I can see it
on the analog M-1000 meter on the tuner, and I can read and lock it with peak hold
on my Telepost LP500.   It is there.   But it hurts nothing!
At least with my Elecraft KPA-500, Henry 2K Classic, tuners, and antenna's.

But certain fussy AMPs might not like the spike.

Neal
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K7JQ
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Posts: 953




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« Reply #7 on: May 13, 2017, 05:21:07 PM »

You guys all seem to be assuming that this is an SSB thing :-)

Neal

No problem on CW and RTTY with my Acom 1500 either. And no problem with my IC-7600.

73, Bob K7JQ
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KB1GMX
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Posts: 1500




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« Reply #8 on: May 13, 2017, 05:41:37 PM »

The problem with spiking is common to many radios and its a side
effect of how they do power reduction.

Most ( broad I know but, applies) radios do power reduction by offsetting
the internal ALC to match power out.  The problem is that the initial tone
will achieve full power before ALC correction is developed.  Some radios
this is more pronounced but its fairly common.  This is a big issue for
FET input amps that do not need high input power and can be damaged
by it.

There are likely some radios that use drive reduction either by gain reduction
in the power chain or a variable attenuator in the transmitter.  Spiking is less
likely due to reduced signal to drive the amp to full power.

There are two solutions:

 Switched power attenuator that allows using full power to the amp but attenuated
 to the desired power needed.  Usually home brewed as I know of none on the market
 (NO exhaustive search performed).  For the FET amps this is the preferred path with
 many radios that cannot or do not have a suitable power reduction mode without
 spiking.

 Alternate but with risk. Lower the audio drive to the transceiver and do not use the
 built in power reduction as TX power is proportional to TX audio drive.  The risk is
 if you forget the full power available may hit the amp (or transverter if used).  This
 also the desireable for some of the data modes, take care using this as one error
with gain control could overdrive something.

 Allison
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K6AER
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Posts: 4671




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« Reply #9 on: May 13, 2017, 06:58:49 PM »

Well, I did not check my 7300 in the data mode to see if there was a power overshoot. I set the HP 8953E spectrum analyzer for max (peak)  hold and proceeded to key the radio at different power levels 10-100 watts.  At no point did the radio go beyond the set power level. We also checked it in CW, AM FM RTTY and Data modes. If you transceiver is having power spikes I would reset the radio and if that doesn't work, reload the software. Current software level is 1.14. If non of that works then it is off to ICOM.
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KI7DUX
Member

Posts: 28




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« Reply #10 on: May 18, 2017, 11:57:14 PM »

I have this problem too. On SSB, occasionally, my amp goes in fault mode on keying down the PTT.

I prepared a video to show the overshoot measured with an Ameritron AWM-30B, that is supposed to show peak readings. The overshoot was clearly visible.

I contacted Icom support here in Japan and showed them the video. They asked me to send both my 7300 and my amp to their laboratory in Osaka.

After more than two months this is the gist of their answer:
- We verified that occasionally your amp triggers the fault mode.
- The radio works within specs.
- Your wattmeter is faulty.
- We discovered that feeding the amp with a bigger power supply causes that amp to trigger less often.

Needless to say I wasn't particularly happy with the answer.

Luca
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VK3BL
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« Reply #11 on: May 19, 2017, 03:36:52 AM »

I have this problem too. On SSB, occasionally, my amp goes in fault mode on keying down the PTT.

I prepared a video to show the overshoot measured with an Ameritron AWM-30B, that is supposed to show peak readings. The overshoot was clearly visible.

I contacted Icom support here in Japan and showed them the video. They asked me to send both my 7300 and my amp to their laboratory in Osaka.

After more than two months this is the gist of their answer:
- We verified that occasionally your amp triggers the fault mode.
- The radio works within specs.
- Your wattmeter is faulty.
- We discovered that feeding the amp with a bigger power supply causes that amp to trigger less often.

Needless to say I wasn't particularly happy with the answer.

Luca

But what amp was it?
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J.D. Mitchell - VK3BL / XU7AGA - http://vk3bl.wordpress.com
KI7DUX
Member

Posts: 28




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« Reply #12 on: May 21, 2017, 05:47:44 PM »

But what amp was it?

The amp is a RM Italy HLA-305V Plus, but I do not see how that can make any difference.

A radio triggers pretty regularly the safety of an amp. The same radio shows a power overshoot when attached to a wattmeter. What does the manufacturer of the radio have to say about it? That the radio is perfectly fine and that both the amp and the wattmeter have two unrelated malfunctions. Yeah, sure, what are the chances?

Luca
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K6AER
Member

Posts: 4671




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« Reply #13 on: May 21, 2017, 07:58:50 PM »

The RMA-305 will drive to full output with 10 watts input. What is your power output on the 7300 set at and limiting the maximum power to 10 watts is a bit harsh for the ALC on a 100 watt radio.
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KI7DUX
Member

Posts: 28




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« Reply #14 on: May 21, 2017, 08:36:40 PM »

The RMA-305 will drive to full output with 10 watts input. What is your power output on the 7300 set at and limiting the maximum power to 10 watts is a bit harsh for the ALC on a 100 watt radio.

The radio is the 50W model. Depending on the band, I drive the amp with anything between 7% and 15%. Anything more than that will cause the amp to trigger the safe mode.

One suggestion I read in this thread, but have not tried yet, is to set some TX delay. I wonder if that may make some difference.

Luca
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