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 Post subject: No SWR reading / low PEP
PostPosted: Mon Apr 11, 2016 5:42 pm 
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Joined: Mon Apr 11, 2016 4:09 pm
Posts: 9
Hi all!

Finished my HR50 today, been testing it out and noticed some odd behavior when TXing.

I have it set up to TX via COR until I get time to make the FT-817 interface cable.

When I transmit a carrier in CW mode using my straight key, I get the following reading:

Image

I'm TXing at 5W from the FT-817.

Can anyone help me troubleshoot what the issue might be?


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PostPosted: Mon Apr 11, 2016 8:45 pm 
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Joined: Mon Jul 23, 2012 6:25 am
Posts: 1142
OK, it's switching to TX but nothing is coming out...

Did all of the resistance test go OK?

Were you able to set the bias correctly?

Do you have any options, QSK, ATU, Driver?

Can you tell about how much current the amp is drawing when you transmit?

If you turn the amp off but leave it in line, does the power from your FT-8a7 make it to the antenna?

Is it OK in RX?

73,
Jim WA2EUJ


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PostPosted: Mon Apr 11, 2016 9:38 pm 
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jimveatch wrote:
OK, it's switching to TX but nothing is coming out...

Did all of the resistance test go OK?

Were you able to set the bias correctly?

Do you have any options, QSK, ATU, Driver?

Can you tell about how much current the amp is drawing when you transmit?

If you turn the amp off but leave it in line, does the power from your FT-8a7 make it to the antenna?

Is it OK in RX?

73,
Jim WA2EUJ

Hi Jim,

Yep, the tests all passed with flying colors and I was able to set the biases correctly.

I have no options (QSK/ATU/Driver).

Assuming I'm measuring the current correctly, when triggering the amp using COR and a carrier wave, the initial current draw is ~40mA. When the amp unkeys, that jumps briefly to 1.85A before dropping back down to 0.

I can still hear everything fine through the radio even when the amp is powered off.
I can also transmit just fine when the amp is off, — I'm getting spots from reversebeacon.net and PSKreporter.

Seems fine in RX. Might be a little less clear, but not sure if that's just my ears playing tricks on me.

Could it be an issue with T3? Not sure exactly how strict "no wires should cross each other" is, it's pretty tight in there...


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PostPosted: Tue Apr 12, 2016 5:55 am 
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The current I'm interested in is during TX. If you apply drive and the amp draws less than 1 or 2 amps then it's a good bet that the drive isn't making it to the amplifier. If it draws 5 or more amps the the drive is making it to the amp but the output isn't making it out.

Post a picture of T3 and I can see if there's something amiss. T3 is only used to drive the meter so if it's something's wrong you would usually get power output but nothing on the meter. I forgot to ask; can you verify that there is actually no power coming out of the amp? or is it just that there's no displayed power.

Also check W1 which is close to T3 on the amp board. It should have a jumper on the RLY side.

73,
Jim WA2EUJ


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PostPosted: Tue Apr 12, 2016 10:11 am 
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Joined: Mon Apr 11, 2016 4:09 pm
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Jim,

Here's a youtube video of what I see when I apply drive to the amp through my radio.

Also, here's a picture of T3 and the relay jumper:

Image

According to my wattmeter, there is no power exiting the amp when keying.

Thanks,
Ben


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PostPosted: Tue Apr 12, 2016 11:44 am 
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Joined: Mon Apr 11, 2016 4:09 pm
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If I key the amp using PTT (by shorting the center pin to ground) I show 1.94A out.


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PostPosted: Thu Apr 14, 2016 9:07 am 
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Joined: Mon Apr 11, 2016 4:09 pm
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Any ideas?


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PostPosted: Thu Apr 14, 2016 2:24 pm 
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Joined: Mon Apr 11, 2016 4:09 pm
Posts: 9
Found the problem.

Apparently skipped over the part where it said 'solder the tabs on T2 to the board'.... :?

Power is getting out now. Going to do a more thorough test later.


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PostPosted: Thu Apr 14, 2016 3:24 pm 
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Joined: Mon Jul 23, 2012 6:25 am
Posts: 1142
Great, I'm glad that you found the problem. Let us know if you need any additional help.

73,
Jim WA2EUJ


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