Icom: Will ICOM 7300 Internal tuner etc handle heavy duty cycles like SSTV?

[Retroradio]

New to me ICOM 7300. Will it do SSTV etc... without an external tuner?
It doesn't like my external tuner.
Im using a 5BTV antenna and a 30amp PS....before anyone asks....

 

[tweiss3]

IRC, it will only tune a a SWR 3:1 to below 1.5:1. If you have a greater miss match, you will need an external tuner.

 

[WA0CBW]

If it doesn't like your external tuner then it is unlikely the internal tuner will be able to find a match.

 

[popnokick]

"Heavy duty cycle" (which you state in the thread subject) has nothing to do with SWR. But the SWR-related responders are correct... if your antenna is above the SWR values given then the external tuners - which usually are more tolerant of greater SWR mismatch - can't tune a better match, then the internal 7300 tuner is not going to be able to do it either. ALSO - if you are using an external tuner on the 7300, bypass / disable the internal tuner. This can be done with settings on the radio; you don't want two tuners inline with the antenna.
So back to "duty cycle" that you asked about in the subject of this thread. SSTV, RTTY, and digital modes can have high duty cycles (which is basically a lot of "key down" full power transmit RF from the finals to the tuner). Which is why many of the external tuners will describe their power ratings in their instructions for different modes. Typically SSB and CW modes can be used at the full output power setting on the radio. But the instructions / specs will read something like this: 0.1 to 125 Watt SSB/CW, 30W Digital. Be sure to reduce your Tx power output (in this case to 30W for digital modes) unless you have an external tuner that is rated at the 7300's full output power (100W).

 

[jwt873]

The internal tuner should be able to handle all the power your radio can produce.. (Would be a pretty poor radio design if it didn't).

You don't mention which external tuner you were using, but external tuners can usually match a wider range of SWR compared to the internal ones. As WA0CBW points out your internal tuner might not be able to do the job... Only way to tell is to try...

 

[tweiss3]

I missed that you were having trouble with an external tuner. Is it an automatic tuner or manual? Is the radio set correctly and the cable hooked up for control/tuning?

As stated above, you do need to disable the internal ATU.

As far as external tuner, if you want 100W RTTY, the only tuner I've been able to find that will handle 100W digital is the LDG AT-600ProII. It can bring up to 10:1 down to acceptable levels and will do 160-6m up to 250W digital and 600W SSB/CW.

You may also need to look at manual tuners to get it close enough for use. Your 5BTV should work well with the internal ATU, but as the instructions indicate, you need to tune each band correctly for it to work well and get within acceptable SWR.

 

[Retroradio]

If it doesn't like your external tuner then it is unlikely the internal tuner will be able to find a match.

Took the external out of line and achieved a perfect match with the internal. Albeit the antenna is almost flat across all bands anyway.

I missed that you were having trouble with an external tuner. Is it an automatic tuner or manual? Is the radio set correctly and the cable hooked up for control/tuning?

As stated above, you do need to disable the internal ATU.

As far as external tuner, if you want 100W RTTY, the only tuner I've been able to find that will handle 100W digital is the LDG AT-600ProII. It can bring up to 10:1 down to acceptable levels and will do 160-6m up to 250W digital and 600W SSB/CW.

You may also need to look at manual tuners to get it close enough for use. Your 5BTV should work well with the internal ATU, but as the instructions indicate, you need to tune each band correctly for it to work well and get within acceptable SWR.

Disabling the internal tuner is an option that I had not read about so this tuner issue now makes sense. Only had the radio a day....lol

"Heavy duty cycle" (which you state in the thread subject) has nothing to do with SWR. But the SWR-related responders are correct... if your antenna is above the SWR values given then the external tuners - which usually are more tolerant of greater SWR mismatch - can't tune a better match, then the internal 7300 tuner is not going to be able to do it either. ALSO - if you are using an external tuner on the 7300, bypass / disable the internal tuner. This can be done with settings on the radio; you don't want two tuners inline with the antenna.
So back to "duty cycle" that you asked about in the subject of this thread. SSTV, RTTY, and digital modes can have high duty cycles (which is basically a lot of "key down" full power transmit RF from the finals to the tuner). Which is why many of the external tuners will describe their power ratings in their instructions for different modes. Typically SSB and CW modes can be used at the full output power setting on the radio. But the instructions / specs will read something like this: 0.1 to 125 Watt SSB/CW, 30W Digital. Be sure to reduce your Tx power output (in this case to 30W for digital modes) unless you have an external tuner that is rated at the 7300's full output power (100W).

Good point on reducing output power. The reason I mentioned the Antenna Tuner/SWR is I was advised that that model of tuner would not handle a heavy duty cycle. I had without thinking linked that info togethe. I am going to use the internal tuner for now bit drop the output power (30Watts) for SSTV, PSK31 etc...

Thanks all for the great info!

 

[vagrant]

What is your SWR on 14.230?

Never mind, you resolved it.