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Author Topic: Tuning for reduced output power FT-101ZD.  (Read 405 times)

KF4ZGZ

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Re: Tuning for reduced output power FT-101ZD.
« Reply #15 on: November 04, 2019, 01:25:41 AM »

True about the ZD manual ... the earlier manuals are clearer and achieve the same purpose.
And I have given him those steps.

Nick, all you have to do is follow normal tuning procedure ..... just don't bother tuning for peak output.
Tune for peak at 50 watts and stop there.
Your tubes will live forever!
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Matt

N8FVJ

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Re: Tuning for reduced output power FT-101ZD.
« Reply #16 on: November 09, 2019, 08:39:00 AM »

I believe reducing drive also reduces receiver reception. Get a potentiometer and 9 volt battery. Apply a negative voltage as adjusted by the potentiometer to the ALC input and adjust power output.
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VK6HP

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Re: Tuning for reduced output power FT-101ZD.
« Reply #17 on: November 09, 2019, 04:38:25 PM »

I realize this is the internet where any or no standards apply but did you not see that that the pot suggestion has been made twice before in this thread? And that it transpired that the OP does not actually want to reduce the output to below 100W?  And that in his radio the "carrier level" is controlled by the "drive" control; the "pre-selector" tuning control is a different front-panel control.

The OP was clearly trying to get his head around some unfamiliar technology and I don't understand posts that diminish the signal-to-noise of the explanation that resolved his difficulties.  To drop a rubbish post at the end of the thread is potentially confusing to him (although he sounded like a fellow sensible enough to calibrate responses) and discourteous to the previous posters.

Peter.
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W0CKI

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Re: Tuning for reduced output power FT-101ZD.
« Reply #18 on: November 09, 2019, 04:42:55 PM »

Reducing drive does not reduce RX sensitivity. If there is a preselector on the radio then that affects RX
Gary W0CKI
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W0CKI

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Re: Tuning for reduced output power FT-101ZD.
« Reply #19 on: November 09, 2019, 05:56:56 PM »

Or the pre selector could be part of the final dipping process..there are tuning instructions on the net. Have you looked for Yaesu hybrid tuning guides?
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KB0TJ

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Re: Tuning for reduced output power FT-101ZD.
« Reply #20 on: December 01, 2019, 11:21:12 AM »

I use my FT-101ZD MK III regularly, and have refurbished a number of them.  Actually, I have two of them here right now.
Hopefully you have an RF cage fan mounted... if not, as a novice/intermediate user, go buy one and install it.

Basically, the PRESELECT control has three tuneable slugs. They do work in harmony with the transmitter and the receiver. It's called resonance.
The receiver section uses two of them and one of those two is actually shared with the 12BY7 driver tube, and ALC circuit...

The two 6146B tube's cathodes are held above ground with a single precision resistor, which when switched in, is in parallel with the panel meter movement.
This resistor is the tube's cathode, screen and plate "current", shunt resistor for the IC meter.
It allows you to read the two power tube's total current flow under idle (with no signal, drive or "carrier"), and again, under driven conditions for actual power input. Not RF output.
The thing is that it is measuring DC cathode/plate current and DC screen current so it's not really a good indicator of any power output.
But very useful as a visual guide for tuning to resonance and max power out.

Set the PO-IC-ALC switch into IC mode (again, it's only measuring "total" DC current through the two 6146B).

TUNE mode
VOX GAIN control in MOX while only intermittently TX testing:

Check the idle current of the tubes is set to 50ma with no drive or signal.
This is adjustable too, but read the manual on how to do it, and don't exceed 50ma if you have to adjust this setting.

TUNE mode.
Tuning:
Pick you band and connect to a 50 ohm dummy load.
Read the manual for approximate settings, by bands/frequency, of the three controls, PRESELECT, LOAD and  PLATE.

VOX GAIN control in MOX
Work your way up with the drive control and keep adjusting the PRESELECT, LOAD AND PLATE controls set for maximum output, while continuing the "dipping" of the PLATE current control as you go, finally stopping at a tuned output of around 100-110 watts.
Into my external wattmeter, the plate current on both radios show about 270ma to 280ma at this point.
If the two tubes were perfectly matched (they will not be), that is around 137ma each of DC current.
These tube are quite robust if you are careful with key down and transmit time cycles, you can run at 125ma-150ma each for years and years.

Now the final section is all tuned up....
To limit your output power on voice, when desired, turn the MIC GAIN control from zero, counter clockwise, to maybe as high as 11:00, depending on what kind of mic you are using.
So keep this in mind, in voice mods you'll be mostly using your MIC GAIN control to limit power output and voice peaks and in CW you'll be using the DRIVE control for power output.

I just tried mine and with the meter set to IC, USB or LB and while turning the MIC GAIN slowly up from zero, firmly saying FOUR, with the what meter in PEAK reading mode, the needle flicking forward to about 70ma-75ma, I'm getting about 10-15 watts output.
Same thing with MIC GAIN up to about 100ma is 50 watts.
150ma is peaking at over 100 watts peak output.
Looking at the mic gain control, the pointer is almost at the 9:00 position and the radio is making 100 watts PEAK and AVERAGE almost 45-50 watts!

So going a little further with MIC GAIN control to 175ma to 200ma, PEAK power is around 125-140 watts, AVERAGE is about 65-75 watts.
Read up on peak envelope power.

From this you might be able to see how easy it is to overdrive these things and sound like crap with the MIC GAIN set too high.

REMEMBER:
All of this VOICE mode stuff was done with the DRIVE control at ZERO!!
CW is a different thing and you need the DRIVE control for those power output settings.

When comfortable with all the above, now in USB or LSB you can mess with the COMP LEVEL PROC... but that does require you using the drive control for that extra punch.... just not anywhere as much as you think you need.

It's all in the YAESU FT-101ZD manual.
 
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2E0LPL

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Re: Tuning for reduced output power FT-101ZD.
« Reply #21 on: December 01, 2019, 02:30:59 PM »

VOX GAIN control in MOX
Work your way up with the drive control and keep adjusting the PRESELECT, LOAD AND PLATE controls set for maximum output, while continuing the "dipping" of the PLATE current control as you go,

Bruce you confuse me me.

You say keep adjusting preselect load a plate for max out....then say continue to dip the plate...is that not what being done in the above instruction...or have I missed something.
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AC2EU

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Re: Tuning for reduced output power FT-101ZD.
« Reply #22 on: December 01, 2019, 06:59:09 PM »

VOX GAIN control in MOX
Work your way up with the drive control and keep adjusting the PRESELECT, LOAD AND PLATE controls set for maximum output, while continuing the "dipping" of the PLATE current control as you go,

Bruce you confuse me me.

You say keep adjusting preselect load a plate for max out....then say continue to dip the plate...is that not what being done in the above instruction...or have I missed something.
Yes, adjust the preselect for max ( this will affect receive too). Dip the plate ( this ensures resonance in the finals)
Adjust the drive control for the desired maximum or minimum power output.
DO NOT off tune the transmitter to lower the power. Both controls should be in peak and dip respectively.
BTW the load and plate controls are interactive , so you might have to go back and forth to get the best match, depending on the antenna...

Bottom line: The finals will run cooler and last longer if everything is in proper tune. Use the drive control to control the power. Easy peazy.

I'm sure someone will come along and tell me I'm wrong, but I own a FT-101EE and know how they work.

KF4ZGZ

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Re: Tuning for reduced output power FT-101ZD.
« Reply #23 on: December 03, 2019, 03:31:01 AM »

I re-read my last post and I could have worded that better.

Nick, follow your regular tune-up procedure ..... just tune up for it to peak at 50 watts and not to peak at 100 watts.
You can also follow what was just posted .... which you have been told by many others, then just reduce the drive.
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Matt

G3RZP

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Re: Tuning for reduced output power FT-101ZD.
« Reply #24 on: December 03, 2019, 07:56:34 AM »

I would be very careful about using the FT101ZD on 18MHz. The three I have looked over the years had an unacceptable level of 18MHz from the second harmonic of the IF - about -30dB or so. Which is one reason that the FT102 has an IF of 8.215 MHz. At any output over 5 watts, that second harmonic of the IF needs to be 50dB down. Pity, because it's a fine rig otherwise. But requirements have tightened up since it was designed.
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KB0TJ

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Re: Tuning for reduced output power FT-101ZD.
« Reply #25 on: December 06, 2019, 04:40:20 PM »

VOX GAIN control in MOX
Work your way up with the drive control and keep adjusting the PRESELECT, LOAD AND PLATE controls set for maximum output, while continuing the "dipping" of the PLATE current control as you go,

Bruce you confuse me me.

You say keep adjusting preselect load a plate for max out....then say continue to dip the plate...is that not what being done in the above instruction...or have I missed something.


***************

That is correct. When the RF output is as high as it can go by setting the PRESELECT,  PLATE AND LOAD controls for max power, go back to IC position for the meter, use the PLATE control and "dip" the current reading for minimum DC current.
You might have to move it much at all.
If your radio is all set up correctly and the tubes are good... the dip and the max power output will be in nearly the same place while reading your IC meter.
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