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 Post subject: RS-HFIQ Setup Redux
PostPosted: Tue Nov 20, 2018 3:56 pm 
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Joined: Mon Nov 28, 2016 1:30 pm
Posts: 59
Hi,
Background
RS-HFIQ, built the PCBA myself.
HR-50 with ATU

I have had the RS-HFIQ for some time but have stopped using it after getting terrible audio reports. I have decided to go through the setup again to try to sort it out.

I am at the first step as described on the wiki:

"With the tone running, adjust the Speaker level in the Windows Sound panel for 5W output. If you aren't using a wattmeter set it just before the red LED lights on the RS-HFIQ and if you are using an antenna rather than a load, do it quickly. Press CTRL+SHFT+G repeatedly to cycle through the tones until the transmitter unkeys.

With the tone running, adjust the Speaker level in the Windows Sound panel for 5W output. If you aren't using a wattmeter set it just before the red LED lights on the RS-HFIQ and if you are using an antenna rather than a load, do it quickly. Press CTRL+SHFT+G repeatedly to cycle through the tones until the transmitter unkeys."

I have the three tones running into a dummy load. I am using a HR-50 with ATU in bypass/wattmeter mode. I am adjusting the speaker level and the power goes up to ~2.6W and then decreases as the level is increased.

Any idea on why this is? RS-HFIQ internal drive level incorrect?

Thanks

Rich


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 Post subject: Re: RS-HFIQ Setup Redux
PostPosted: Wed Nov 21, 2018 6:51 am 
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Joined: Mon Jul 23, 2012 6:25 am
Posts: 1123
Hi Rich,

With 3 tones, the PEP per tone is going to be 1/9th of the PEP of the RS-HFIQ's amplifier, or just over 1/2 watt. With a complex signal consisting of three separate tones there's no telling what the wattmeter is actually reading; it could be average, PEP or somewhere in between. As you increase the drive on the three tones, the RS-HFIQ starts to create distortion products which may lower the average power. With 3 tones, a reading of 2.6W most likely indicates an overdrive situation.

Testing with multiple tones is for determining the distortion characteristics of the amplifier. For setting levels you should be using a single tone at 0 dB FS (the third selection). This insures that any thing coming out of the A/D will remain linear in the amplifier.

73,
Jim WA2EUJ


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 Post subject: Re: RS-HFIQ Setup Redux
PostPosted: Wed Nov 21, 2018 12:15 pm 
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Joined: Mon Nov 28, 2016 1:30 pm
Posts: 59
Jim,
That makes a lot of sense. I will re-check with a single tone. I went back and checked the idle current of the final and it was way high, ~1 amp. Not sure how that happened but I backed it down to ~450mA on top of the RX current.

Thanks for the help

Rich


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 Post subject: Re: RS-HFIQ Setup Redux
PostPosted: Fri Dec 07, 2018 12:47 pm 
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Joined: Mon Nov 28, 2016 1:30 pm
Posts: 59
Jim,
I am still unable to get 5W, I can get 3W max. I checked with two wattmeters. Final bias is set at 450 mA. I have replaced the PA FET, no change. I updated (I think) the Startech drivers, no help. I have to have the knob on the Startech USB sound card all the way up to get output. I have to leave the soundcard set at 16 bit and 48 KHz or things hang.

Any ideas?

Thanks

Rich


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 Post subject: Re: RS-HFIQ Setup Redux
PostPosted: Sat Dec 08, 2018 8:58 am 
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Joined: Mon Jul 23, 2012 6:25 am
Posts: 1123
Hi Rich,

Do me a favor, listen to the tones that the StarTech is driving the RS-HFIQ with, make sure that a tone is present in both channels. If you can try one of the free soundcard o-scope programs to look at the tones and see if they at 90 degrees apart. If there is tone on only one channel or they aren't at the correct phase, the mixers won't cancel the alternate sideband and the average power (read by the meter) will be lower than with a single tone.


Here is a link to another TX utility:

https://www.dropbox.com/sh/yz7v6jo7wxqoaco/AABVldy7IVVbaqblzZrDZLMna?dl=0

Set the RS-HFIQ on frequency using HDSDR or Termite then start this program and see what you get for output power.


73,
Jim WA2EUJ


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 Post subject: Re: RS-HFIQ Setup Redux
PostPosted: Mon Dec 10, 2018 12:22 pm 
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Joined: Mon Nov 28, 2016 1:30 pm
Posts: 59
Jim,
I am seeing good waveforms at the input jack using the utility that you provided. I am still seeing only about a quarter watt of output. When I use the internal tone generation from HD SDR I don’t see these pretty waveforms. Right now I am thinking I’m not getting good output from HDSDR and I may have a hardware problem.

Rich

https://i1227.photobucket.com/albums/ee ... w.jpg.html


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 Post subject: Re: RS-HFIQ Setup Redux
PostPosted: Mon Dec 10, 2018 2:43 pm 
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Joined: Mon Nov 28, 2016 1:30 pm
Posts: 59
Jim,
One thing to know is that, originally, the RD16HHF1 final I purchased was counterfeit. This resulted in a dead short and burned traces. I replaced the final and repaired the traces and had good results for a long time. Perhaps some ancillary components were damaged and have now failed. I can order new components in the final/PA area and replace them (hammer approach).

The G3PLX's utility seems to do a frequency sweep so I cannot stay on one frequency. If I am close to it's frequency I get ~0.25W out but I can see up to 3W out if I tune around.

I am going to get the IQ32 upgrade kit but I want to make sure the RS-HFIQ is working first.

Rich


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 Post subject: Re: RS-HFIQ Setup Redux
PostPosted: Mon Dec 10, 2018 4:40 pm 
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Joined: Mon Jul 23, 2012 6:25 am
Posts: 1123
Hi Rich,

I hadn't realized that the PA was suspect. If you want to, you can send it to me and I can have a look at the final and make sure that everything is OK. If you want to then buy the upgrade kit, I'll send back a working IQ32. Contact me at jim (at) hobbypcb (dot) com and we can make the necessary arrangements.

73,
Jim WA2EUJ


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