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Author Topic: Yaesu FT-897D AM power problem  (Read 2685 times)
WA1GJF
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Posts: 11




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« on: May 07, 2013, 08:14:51 AM »

My Yaesu FT-897D has only 2-3 watts of AM output on the HF bands.  The internal alignments have been tweaked.  However, I do not have a scope or good signal generator to make serious changes.  SSB, CW, etc. all have full power.
Does anyone have any suggestions?
Rig is stock, no mods.
Thanks!

Leeds

WA1GJF
wa1gjf@arrl.net
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AA4HA
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Posts: 1378




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« Reply #1 on: May 07, 2013, 08:48:14 AM »

Are you modulating the audio while measuring the power?

Also, measuring power with speech can be tricky and many use a peak reading wattmeter. There is a thread on that subject at;

http://www.eham.net/ehamforum/smf/index.php?topic=69608.0

If your mic gain is too low the power will look horrible. If it is too high you will be clipping. That is the real advantage of having a scope, to see when you are flat-topping.
« Last Edit: May 07, 2013, 08:53:11 AM by AA4HA » Logged

Ms. Tisha Hayes, AA4HA
Lookout Mountain, Alabama
W8JX
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Posts: 5489




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« Reply #2 on: May 07, 2013, 09:52:02 AM »

My Yaesu FT-897D has only 2-3 watts of AM output on the HF bands.  The internal alignments have been tweaked.  However, I do not have a scope or good signal generator to make serious changes.  SSB, CW, etc. all have full power.
Does anyone have any suggestions?
Rig is stock, no mods.
Thanks!

Leeds

WA1GJF
wa1gjf@arrl.net


You have to set carrier/power level and it will only do 25 watts carrier no signal and 100watts PEP.
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WA1GJF
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Posts: 11




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« Reply #3 on: May 07, 2013, 12:34:29 PM »

Thank you for your replies.  Unless I am missing something, there should be 25 watts of unmodulated carrier, which I am not getting.  The watt meter shows only  3 watts.   Please note that I am looking at AM carrier, not SSB, or CW, which are performing to spec.
Leeds

WA1GJF
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WB2WIK
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Posts: 20547




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« Reply #4 on: May 07, 2013, 03:29:41 PM »

Thank you for your replies.  Unless I am missing something, there should be 25 watts of unmodulated carrier, which I am not getting.  The watt meter shows only  3 watts.   Please note that I am looking at AM carrier, not SSB, or CW, which are performing to spec.
Leeds

WA1GJF

What power level do you have it "set" to?
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WA1GJF
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Posts: 11




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« Reply #5 on: May 07, 2013, 04:13:56 PM »

"Set to?" No matter how much I try to increase power through the menu, the power does not change. My old Heathkit AM rigs, the home brew ones I built, the FT890AT that still lives on, all put out the proper amount of power by increasing the power level..  It is  not a matter of "what setting", as I can "crank it up all the way" and still get 3 watts.  I have spoken with a tech at Yaesu, and he was stumped.
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N8NSN
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« Reply #6 on: May 07, 2013, 05:25:41 PM »

Most likely, from watt (pun) you described; somehow the "hidden menues" have been altered or not set correctly from the factory. There are 74 settings not covered in the user manual. These settings cover internal programming for everything from receiver gain (per band) to mode output levels. Number 060 in the hidden menue deals with AM-CAR-LEVEL. From the factory the setting should be 136 ish. I dropped mine down to 95, which provides me 10 watts of AM carrier, and AM PEP of 30 watts out - - for driving a KW amp on AM mode. Works beautifully.

HOWEVER, though I still have the list printed of what the 74 functions of the hidden, service menue - I forget how to get in to this menue. The silver lining is... You guessed it - the Fox Tango Group will surely be able to get this information to you.

WORD OF WARNING... If you are even remotely unaware of ANY of the functions these menue items alter - - DON'T mess with them or you could really mess things up. I mean these 74 settings control EVERYTHING.

I also altered mine to my lowest HF CW power out is half of 1 watt, instead of the factory set of 4 watts. Why? Because QRPPis fun :-) unless it is an unintentionally achieved.

I hope my assumptions are correct. Because if so, this is an easy fix. It'll boost your confidence, and you'll become thirsty for more knowledge... That's a cool part of this hobby. Plus when I learned about these neato menues, it was like an epiphanous understanding of just how cool digital circuitry has become.

GL & 73
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N3DT
Member

Posts: 490




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« Reply #7 on: May 07, 2013, 05:26:54 PM »

What are you measuring the PO with?

What are you feeding the output antenna port into?

Are you using the correct antenna port out.

There are too many things you are not telling us.

I'm thinking it's 'static between the earphones', but I can be wrong.  But usually one needs to inspect what is really going on, if everything else is working I doubt if anything is wrong other than operator error.  Like I say, I could be wrong, I'm not trying to be rude.

Good luck.
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N8NSN
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Posts: 283


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« Reply #8 on: May 07, 2013, 05:40:43 PM »

Ahhhhh.

Here you go:

http://www.worldwidedx.com/yaesu/59303-yaesu-ft-857-897-am-operation.html

Remember... CAUTION !
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N8NSN
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Posts: 283


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« Reply #9 on: May 07, 2013, 06:05:54 PM »

The internal alignments have been tweaked. 

Rig is stock, no mods.
Thanks!

Leeds

WA1GJF
wa1gjf@arrl.net


I just re-read this:

Uh-oh !

I sure hope you didn't screw up the bias on the drive and final transistors. This maybe a rather expensive learning experience for you, otherwise.

Just some advise. Don't tweek ANY radio without proper alignment tools. Scope, band scope, signal generator, two tone AF generator.... Etc. etc...

Menu settings are completely different than actually "tweeking" actual components. If you tweeked the bias, etc. no menu alterations will be "normal" in supplying correct voltages to the tweeked parts,until said tweeked components are EXACTLY back to where they should be.  In fact, if you hosed the bias, it's only a matter of time before the factory smoke supplied in one or more of the components finds it's way out with a "ssssT- snap".
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WA1GJF
Member

Posts: 11




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« Reply #10 on: May 08, 2013, 04:15:33 AM »

For James, N8NSN, thank you for taking the time for a rational explanation of the situation and possible resolution, instead of assuming it was static between the ears, or brazen stupidity.  You are right on the money regarding the sub menu and its intricacies. I have tread VERY carefully there, and not messing with it beyond #60.  Regrettably, the power did not change when this adjustment was made, so it may be time to ship the radio off to a repair shop equipment needed to do it right. Every radio does have its unique setting parameters. 
Now, where is that 6L6 for the 80 meter transmitter?.....
By the way, speaking of QRPp, here, you will find a couple of Rock-mites, Tuna-Tins, some breadboard attempts, and 2 or 3 Pixies.  Who said there is no activity on QRPp?

Leeds
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KA4POL
Member

Posts: 1927




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« Reply #11 on: May 08, 2013, 08:13:46 AM »

Measuring power should be done with a dummy load, not an antenna. This would exclude any influence on that side.
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