The Mk V has alc action in the IF stages that has a slow attack so there is a
possibility of spikes especially when the mike is keyed with push to talk. I
blew out an Ameritron solid state amp with my MK V mysteriously. The fix is to
lower the IF gain on each band so that there is just enough gain in the IF
stages to drive the finals to the desired output. The down side of this is that
the speech processor will not provide super punch on the audio; if you like
contest audio.
>From W8JI website:
Transmit Gain Menus
The FT-1000
MK V has hidden transmit gain menus. They are accessed by pushing and holding
FAST and LOCK while turning the POWER switch on. Both of my MK V's and every
MK V serviced here has had the TX IF gain set too high. This causes first
character clicks on CW and spits and splatter on SSB. Here is how to correct
the IF gain to prevent ALC clipping on leading edges of CW and voice:
Press and hold FAST and LOCK before and during initial POWER on.
Press FAST and
ENT at the same time. You are now in the MENU's and the display should say "0-1
GrPI-cH".
Turn the
VRF/MEM CH counter-clockwise to 9-2. The display should say "t iF - GA in" This
is the transmit IF gain menu.
Turn the SUB
VFO knob clockwise one position to " t iF - 018". This is the 1.8MHz transmit
IF gain.
Press the
ALC/COMP meter selector until the bar graph says "ALC". Set RF PWR knob to
full power.
With the radio on
CW and a 50 ohm dummy load connected, close the key and adjust the MAIN VFO-A
knob until the ALC display is about 75-85% of full scale on the illuminated bar
marked "ALC".
Press the next band button (3.5), make sure the radio is still on
CW, and turn the SUB VFO-B knob clockwise one band to "t iF - 035".
Again adjust MAIN
VFO-A until ALC is at 75-85% of full scale.
Repeat this process through all bands.
Most radios I have tested require a setting of 2 to 4 on TX IF gain, with 3
being the most common setting.
This change will reduce
SSB bandwidth and distortion. It will also reduce keyclicks and annoying thumps
on the leading edge of each Morse character.
Good luck;
Bill
W2
PKY
----- Original Message -----
From: Pat Lees
Date: Sunday, May 24, 2009 7:32 am
Subject: Re: [Yaesu] Anyone using MK-V with Alpha 89?
To: Robert Pack
Cc: ""
> Bob
>
> In the menu system set the max rf output for the mark v for 75
> watts
> that may stop the amp from tripping. Your probably getting a
> spike of
> high out put when it is first keyed, see if lowering the max out
> put
> per the menu helps.
>
> Pat
>
>
> On May 23, 2009, at 11:12 PM, "Robert Pack" wrote:
>
> > I am having issues......not sure at this point if it is a
> radio or
> > amp issue but tomorrow I plan to connect this particular Alpha
> 89 to
> > a different radio (990 or 1000D).
> >
> > The radio mic gain seems to be ultra sensitive. At the 9
> o'clock
> > position the alc is just above the alc scale....move it just a
> hair
> > down and there is practically no alc deflection. I have
> worked with
> > compression as well and cannot seem to find a happy medium.
> >
> > The main problem is that when the alc is higher the amp is
> faulting
> > (Alpha amps will fault into standby for several reasons). It
> seems
> > to fault on certain voice peaks. I do not have alc from the
> radio
> > connected to the amp....tried it and nothing good came from it.
> >
> > I do not know if this is a radio issue or an amp issue but
> just
> > thought I would ask here in the event anyone else has had this
>
> > problem with this particular combination. Once I use a
> different
> > radio tomorrow I should be able to rule out one or the other.
> >
> > Any input is appreciated.
> >
> > 73,
> > Bob NX5M
> > _______________________________________________
> > Yaesu mailing list
> > Yaesu@contesting.com
> > http://lists.contesting.com/mailman/listinfo/yaesu
> _______________________________________________
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>
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