[1000mp] Low Output on the Mark V

Mon, 4 Mar 2002 12:37:58 -0500

Hello Jamie and All Yaesu Fans.....

Thank you for your reply....Although I have written to Yaesu twice now, =
I have received no reply from them....I did try to obtain the latest =
service manual on the radio, but it is back ordered.....you can obtain =
an earlier edition, but since we have new radios, I'm going to wait for =
the latest book.....

I have continued to work on this problem, and I have some observations =
to share, which might be helpful to others, or may merely represent a =
work around for my particular radio.....

The issue with low output on the higher frequencies, appears totally =
related to the automatic antenna tuner.....naturally, the higher =
perceived SWR, the lower the output.....I didn't realize exactly what =
this means on the higher frequencies....but apparently, even a modest =
SWR will limit the output somewhat, especially on ten meters.....

The procedure I have come up with is rather simple, yet =
interesting....you will notice that on SSB, while observing the SWR =
meter in the Mark V, that there will always be an upscale indication =
during modulation....regardless of the match through the tuner....it is =
actually impossible to ascertain the SWR in this manner....

If the match is truly 1:1, the indication in the CW mode will be that =
the indicator will not flicker, and only one bar will be displayed, =
unlike in the SSB transmit position...So, I do the following.....

  a.. Select the desired band of operation
  b.. Lower the RF output control to a minimum setting, perhaps ten =
watts or so
  c.. Preset my amplifier tuning, (band selection, tuning, loading)
  d.. Select the CW mode of operation
  e.. Select the keyer option to send dits at about 50 words per minute
  f.. Engage the transmitter and keyer, and quickly tune the amplifier =
at this low level of input with continuous dits (50% duty cycle)
  g.. Operate the Tuner Button several times,  while sending the dits, =
until the SWR indication stops flickering, and only one bar appears, =
indicating a 1:1 SWR has been achieved
  h.. Retune the Linear for maximum output
  i.. Increase the RF output from the Mark V to achieve full linear =
output (perhaps in one or two steps), which in my case requires about =
110 watts drive for 1.5 KW output with a pair of 3-500ZG's from China.  =
You will notice that at full drive, the SWR meter will still not =
flicker, and only one bar should be displayed.....
  j.. Switch to SSB, and observe power output, and monitor to not exceed =
1.5 KW, by adjusting the RF output control....You will notice that the =
SWR meter is again flickering upward several bars....this is normal.....
Whether you are driving your amplifier, or loading up your antenna, the =
same procedure is required....I force the tuner to operate until it =
matches the load, 1:1, which then guarantees full output....I did not =
seem to be able to achieve the match in SSB, for some reason...perhaps =
your Mark V will work differently, but mine works well in this way, now =
that I have figured out what was happening....

If you can not achieve the 1:1 tuning in CW, reset your tuner's =
memories, and try again...You should be able to achieve a 1:1 match over =
quite a large range of SWR conditions...

I guess afterall, the automatic antenna tuner, is not so completely =
automatic afterall....at least in the case of my personal Mark V.....I =
now achieve at least 170 watts on all frequencies, and the Power Output =
Meter matches my Autek Research WM-1 readings.....this output is similar =
to other Mark V radios from what I have been able to discover.....

Sorry for the length of this posting....let me know how your Mark V =
tuner handles the SWR adjustments.....

Happy DXing and 73,

Mike Schatzberg
WB2AJI
http://www.qsl.net/vu2wap/wb2aji/
----- Original Message -----=20
From: "James Hall" <[email protected]>
To: <[email protected]>
Sent: Wednesday, February 27, 2002 11:34 PM
Subject: Re: [1000mp] Low Output on the Mark V

> Mike:
>=20
> I had a similar problem ... it was a problem with some diodes in the =
output
> section - diodes that act as a low-pass filter - if bad the finals =
think it
> is putting out too little power and jacks up its output.  Eventually =
the
> finals burn out !  The solution (from Andy at Yaesu) is to use the =
diodes
> found in the 1000D which apparently are 'stouter'.
>=20
> Sorry ... off to the shop.  Warranty jobs will be back in under a =
month.
>=20
> Jamie
> WB4YDL
>=20
>=20
> > From: "Mike Schatzberg" <[email protected]>
> > Reply-To: [email protected]
> > Date: Wed, 27 Feb 2002 16:48:37 -0500
> > To: <[email protected]>
> > Subject: [1000mp] Low Output on the Mark V
> >=20
> > Hello Yaesu Fans.....
> >=20
> > My new Mark V always indicates 200 Watts on the PO scale....every
> > band.....with the power output control full clockwise.....
> >=20
> > But my Autek WM-1, Bird 43, and matchbox all say, that the output =
drops to
> > about 175 watts on 20 meters, 150 watts on 15, and 125 watts on 10 =
meters, all
> > into a 50 ohm dummy load, as well as my antenna system.....The rig =
does
> > provide 200 watts on 40 meters and lower....
> >=20
> > It appears that the rig thinks it is putting out 200 watts, as the =
meter
> > indicates full output.....and is limiting the output to the preset =
level of
> > 200 watts....
> >=20
> > I have written to Yaesu and asked for a fix, to avoid sending the =
rig back for
> > retuning....it seems like if I could adjust the power output =
calibration on
> > the higher frequencies, perhaps the rig would output at the correct =
level.....
> >=20
> > No other problems appear to be present....suggestions?
> >=20
> > Thanks and 73,
> >=20
> > Mike
> > WB2AJI
> >=20
> >=20
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> >=20
>=20
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>=20

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