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Author Topic: Finding the DX TX freq on FT8  (Read 4105 times)
VA3VF
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Posts: 772




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« Reply #30 on: October 26, 2017, 12:33:29 PM »

I'm fascinated by the standards used sometimes. Spending money on a great transceiver, tower, beams, amps, makes dxing easier, and it's ok. Using a mode to make dxing easier for a low power transmitter with compromise antenna, it's not. Elitism at its best.  Grin
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AA2UK
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Posts: 291




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« Reply #31 on: October 26, 2017, 01:11:58 PM »

Yes you have already discovered that sometimes the band is not stable for for long.  Sometimes you have a popup station you need, and if you don't get him in a minute or two, he is gone for good.  I see this quite a bit on both the upper bands like 15 and 10 and also on 160 sometimes when europeans come in for a few minutes and then they are gone.

And yes of course it always helps to build the best station you can build. The biggest and best antennas you can afford or are able to put up will go a long way toward success as well as honing your operating skills to ferret out contacts that you want and need.
James my point was there isn't anything automatic about completing FT8 or other digital modes. There's plenty of skill involved.
73, AA2UK
Bill
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W9IQ
Member

Posts: 1707




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« Reply #32 on: October 26, 2017, 01:20:20 PM »

Bill,
Quote
... and enable AP will buy you an additional -4db

Just a friendly note that the unit is dB, not db.

- Glenn W9IQ
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- Glenn W9IQ

I never make a mistake. I thought I did once but I was wrong.
K0UA
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Posts: 1348




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« Reply #33 on: October 26, 2017, 01:56:06 PM »

Yes you have already discovered that sometimes the band is not stable for for long.  Sometimes you have a popup station you need, and if you don't get him in a minute or two, he is gone for good.  I see this quite a bit on both the upper bands like 15 and 10 and also on 160 sometimes when europeans come in for a few minutes and then they are gone.

And yes of course it always helps to build the best station you can build. The biggest and best antennas you can afford or are able to put up will go a long way toward success as well as honing your operating skills to ferret out contacts that you want and need.
James my point was there isn't anything automatic about completing FT8 or other digital modes. There's plenty of skill involved.
73, AA2UK
Bill

We are in complete agreement.
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K0UA
Member

Posts: 1348




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« Reply #34 on: October 26, 2017, 01:59:43 PM »

I'm fascinated by the standards used sometimes. Spending money on a great transceiver, tower, beams, amps, makes dxing easier, and it's ok. Using a mode to make dxing easier for a low power transmitter with compromise antenna, it's not. Elitism at its best.  Grin

While I haven't thought of it like that, I think that is an excellent observation.

Hm.. that makes me wonder of some of the guys with a lot of money invested in towers, antennas, beams and equipment, to get on the honor roll or get their 5 band WAS, feel a little threatened by a guy with some backyard vertical and low power getting within striking distance of those goals using digital modes.   Nah... couldn't be...  Smiley
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AE0Q
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Posts: 64


WWW

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« Reply #35 on: October 26, 2017, 09:52:27 PM »

Hm.. that makes me wonder of some of the guys with a lot of money invested in towers, antennas, beams and equipment, to get on the honor roll or get their 5 band WAS, feel a little threatened by a guy with some backyard vertical and low power getting within striking distance of those goals using digital modes.   Nah... couldn't be...  Smiley

Oh come on, it doesn't take all that hardware to get 5BWAS or DXCC...  I got mine using a TS-450S (100w), using CW and RTTY with an attic fan dipole.  Study propagation, work some contests and it can be done.  I also earned RTTY, QRP and CW WAS with same antenna.

Now getting on the DXCC Honor Roll would definitely be more difficult :-)

Glenn AE0Q
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KD7HNN
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Posts: 60




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« Reply #36 on: October 29, 2017, 01:24:09 AM »

Then after you make the qso, you hope that they understand that nobody cares about eQSL's and they use LoTW.
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KI5LP
Member

Posts: 16




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« Reply #37 on: October 29, 2017, 08:55:16 AM »

 
Quote
For your Tx, it may be more beneficial to to you to transmit as close as possible to 1600 Hz.

No it’s not, at least not with up-to-date versions of WSJT-X and radio link. TX offset is kept constant at around 1500 Hz.
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AA2UK
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Posts: 291




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« Reply #38 on: October 29, 2017, 09:03:58 AM »

Quote
For your Tx, it may be more beneficial to to you to transmit as close as possible to 1600 Hz.

No it’s not, at least not with up-to-date versions of WSJT-X and radio link. TX offset is kept constant at around 1500 Hz.

1500hz is the default setting for FT8. There's no reason to stick with 1500hz in fact it might hurt your chances for a decode being many just leave the CF of 1500hz alone creating too many signals at 1500 to decode.
73, Bill
AA2UK
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KI5LP
Member

Posts: 16




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« Reply #39 on: October 29, 2017, 09:08:12 AM »

Quote
For your Tx, it may be more beneficial to to you to transmit as close as possible to 1600 Hz.

No it’s not, at least not with up-to-date versions of WSJT-X and radio link. TX offset is kept constant at around 1500 Hz.

1500hz is the default setting for FT8. There's no reason to stick with 1500hz in fact it might hurt your chances for a decode being many just leave the CF of 1500hz alone creating too many signals at 1500 to decode.
73, Bill
AA2UK

That’s not what I’m talking about. With rig control, TX anywhere in the pass and your VFO is recalculated to ensure a 1500 Hz offset, which is optimal on many rigs.
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5BWAZ
Member

Posts: 9




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« Reply #40 on: November 02, 2017, 01:07:46 PM »

...nobody cares about eQSL's and they use LoTW.

Of all the well known DXers I've spoken to over the past 25 years from all over the world regarding QSLing, NONE of them care about eQSL's. Some of them upload to eQSL as a courtesy to the DXing community, but not a single one cares about any eQSL awards or confirmations. LoTW IS the only game in town.

So yeah..what he said ^
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AA2UK
Member

Posts: 291




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« Reply #41 on: November 03, 2017, 09:51:53 AM »

Quote
For your Tx, it may be more beneficial to to you to transmit as close as possible to 1600 Hz.

No it’s not, at least not with up-to-date versions of WSJT-X and radio link. TX offset is kept constant at around 1500 Hz.

1500hz is the default setting for FT8. There's no reason to stick with 1500hz in fact it might hurt your chances for a decode being many just leave the CF of 1500hz alone creating too many signals at 1500 to decode.
73, Bill
AA2UK


That’s not what I’m talking about. With rig control, TX anywhere in the pass and your VFO is recalculated to ensure a 1500 Hz offset, which is optimal on many rigs.
1500hz is the actual program's CF it's also the default, 1500hz was chosen because it's in the center of most rigs pass band. When you click on a signal at 1300hz your -200hz from the CF, click on 1800hz and you're +300hz. The VFO is only calibrated once not as the QSO moves along.
Perhaps we agree..........?
Bill, AA2UK
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WD4ELG
Member

Posts: 164




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« Reply #42 on: November 04, 2017, 06:09:58 PM »

With CAT control and SPLIT enabled, the software will change your transmit frequency so that the 1500 Hz tone is placed where you have chosen to listen.

Example: I am tuned to 7074 kHz, watching the waterfall, and I see a station I want to call who is transmitting at 2200 Hz.  I double-click on him. 

With rig control enabled, what happens next?  When it is my turn to transmit, the software will adjust my TX freq to (7074 + (2200-1500))= 7074.7 kHz!  Why?  Because that is by design of the software.

We know that the SSB passband rolls off above and below 1500 Hz by default for most rigs, unless we have tailored the TX on the rig (some of the newer rigs have TX filter shaping).  So, our signal output will be diminished if we're not sending the tone at 1500 Hz.  The software takes care of this for us, and moves the TX frequency so that when it can send a 1500 Hz signal on the desired frequency and get maximum power out.

This is a very neat feature!  How to I turn it on?  Simplest way, and this applies for most rigs, is under the SETTINGS->RADIO, under Split Operation, choose RIG or FAKE IT.  FAKE IT will adjust the single VFO frequency as I described above.  RIG option, if it's working, will set the transmit VFO so that a 1500 Hz tone will be right on the received frequency.  (Personally, I can't get it to work with my FT817 so I choose FAKE IT and it does work perfectly for me).


From the WSJT-X user guide, the following description:

Split Operation: Significant advantages result from using Split mode (separate VFOs for Rx and Tx) if your radio supports it. If it does not, WSJT-X can emulate such behavior. Either method will result in a cleaner transmitted signal, by keeping the Tx audio always in the range 1500 to 2000 Hz so that audio harmonics cannot pass through the Tx sideband filter. Select Rig to use the radio’s Split mode, or Fake It to have WSJT-X adjust the VFO frequency as needed, when T/R switching occurs. Choose None if you do not wish to use split operation.Behavior on the lower right, select "Allow TX frequency changes while transmitting"
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AA2UK
Member

Posts: 291




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« Reply #43 on: November 04, 2017, 07:55:13 PM »

Please provide a link.
Bill, AA2UK



From the WSJT-X user guide, the following description:

Split Operation: Significant advantages result from using Split mode (separate VFOs for Rx and Tx) if your radio supports it. If it does not, WSJT-X can emulate such behavior. Either method will result in a cleaner transmitted signal, by keeping the Tx audio always in the range 1500 to 2000 Hz so that audio harmonics cannot pass through the Tx sideband filter. Select Rig to use the radio’s Split mode, or Fake It to have WSJT-X adjust the VFO frequency as needed, when T/R switching occurs. Choose None if you do not wish to use split operation.Behavior on the lower right, select "Allow TX frequency changes while transmitting"
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K0UA
Member

Posts: 1348




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« Reply #44 on: November 04, 2017, 08:10:08 PM »

Please provide a link.
Bill, AA2UK



From the WSJT-X user guide, the following description:

Split Operation: Significant advantages result from using Split mode (separate VFOs for Rx and Tx) if your radio supports it. If it does not, WSJT-X can emulate such behavior. Either method will result in a cleaner transmitted signal, by keeping the Tx audio always in the range 1500 to 2000 Hz so that audio harmonics cannot pass through the Tx sideband filter. Select Rig to use the radio’s Split mode, or Fake It to have WSJT-X adjust the VFO frequency as needed, when T/R switching occurs. Choose None if you do not wish to use split operation.Behavior on the lower right, select "Allow TX frequency changes while transmitting"

Is this why we see so many overdriven signals that have audio harmonics?.  As an example a station transmitting on 500hz sometimes have harmonics at 1000, 1500, 2000 etc.  Of course if they were driving the audio so hard it wouldn't happen, but I guess if they had split turned on then the actual audio tone fed into the radio would be much higher and have less tendency to generate these horrible looking harmonics?  I know on my rig which has "split, fake it" turned on at all times, when I am transmitting at 500hz, I am actually transmitting a 1500 hz tone and the rig is being moved down 1Khz in frequency and instantly back in receive mode.
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