F1LBY

Sounds like RF feedback to me. If you don't get it on FM. What happens if
you reduce power?
What happens if you TX into a dummy load?
If the fault goes away when keyed into a dummy load, then it looks like RF
is finding its way back into the radio.

If it is RF into the radio then it could be a number of things:
RF picked up by the DC power lead.
RF picked up by the MIC
Poor earthing inside the radio - ensure all screws inside that are
responsible for grounding are tight
Perhaps some ferrites on the mic/dc lead/cw key lead
Is the antenna in close proximity to the radio?
Do you have a good swr? Have you tried an ATU in line?


"www.spook.shows.it" <spook@spooksghostcams.cjb.net> wrote in message
news:bdvujv$9v6$1@news8.svr.pol.co.uk...
> Cheers for the help
>
> I have checked all the conections on the mic.
> I don't have another one to try ;-(
> I pluged a speaker in and it done the same, it fedback like a stage mic.
> one funny thing though it only seems to happen when im on usb/lsb/cw/
> selection or its only noticable <
>
> Ray
> g7duy
>
>
>
> "mike" <mike-g7bnf@nospam.co.uk> wrote in message
> newsWKMa.18596$sh4.1369098@newsfep2-win.server.ntli.net...
> > first confirm it is not the mic.
> > try a different one.
> > if u can't, check the mic plug for touching wire strands in the plug.
> > then make sure that the mic socket on te 757 has not got rotated.
> > this will twist the connectioms together inside.
> >
> > 2nd...try an external specker, it could be the socket spring correded
over
> > time
> >
> > know the 757 well still run & service many
> >
> > let me no how u get on.
> >
> > try another mic first though.
> >
> > mike g7bnf
> >
> > "www.spook.shows.it" <spook@spooksghostcams.cjb.net> wrote in message
> > news:bdvt70$imp$1@news6.svr.pol.co.uk...
> > >
> > > Hi Again
> > >
> > > Can anyone help me, I own a Yaesu 757 gx .and my problem is driving me
> > mad,
> > > you see My mic feedsback through the rig speaker!
> > > Like a pa mic. it only stops when i key the mic up ..
> > > when I put my mic anywhere near the radio, it feeds back .
> > > Please help !
> > >
> > > SpOok
> > >
> > >
> > > www.spook.shows.it
> > >
> > >
> >
> >
>
>

www.spook.shows.it

wow! Thanks for the help
I have tried Most of the Things and it still comes through even with the
dummy load and Atu ;-(
I think it may be the antenna ..... Im only tuning a wire dipole at the
moment,
Its just very anoying ;-(
cheers all great group

Ray

G7duy

"Nathan Higgins" <nathan@link9.net.no-spam> wrote in message
newsLTMa.1936$wT3.15369334@news-text.cableinet.net...
> I would first check the ground on the mic, and on the radio, make sure the
> case it earthed properaly. Normally with RF feedback you would get a low
hum
> similar to mains hum coming through with your tx audio. You say there is
> feedback - if you hold the mic as far awayas possible from the speaker can
> you actually hear yourself talking without any feedback? If so the likely
> hood is that there is a short either in the radio or in either the M/F mic
> socket. Can't see this being a major problem so don't worry too much -
just
> a case of isolating the cause.
>
> Good Luck
>
> --
> Nathan D Higgins
>
> Website: http://nathan.link9.net/
> Email: nathan[at]link9[dot]net
> Hosting: http://www.link9.net
> WAP: http://wap.link9.net
> MSN: nathan[at]link9[dot]net
>
>

mike

not wishing at present to look too closely at the circuits
i'd plumb for it being one of the switching diodes
there are rows of them 1N94 type things.
lots of strange switching faults i have known to be caused by these going.

typically they go short-circuit, easy to find with an OHMS meter.

if u have the service/circuit diagrams, have a look around the audio amp.

if u wish more help
email direct
mike-g7bnf@ntlworld.com.

know the 757 very well.


"www.spook.shows.it" <spook@spooksghostcams.cjb.net> wrote in message
news:be4msk$28h$1@newsg1.svr.pol.co.uk...
> wow! Thanks for the help
> I have tried Most of the Things and it still comes through even with the
> dummy load and Atu ;-(
> I think it may be the antenna ..... Im only tuning a wire dipole at
the
> moment,
> Its just very anoying ;-(
> cheers all great group
>
> Ray
>
> G7duy
>
> "Nathan Higgins" <nathan@link9.net.no-spam> wrote in message
> newsLTMa.1936$wT3.15369334@news-text.cableinet.net...
> > I would first check the ground on the mic, and on the radio, make sure
the
> > case it earthed properaly. Normally with RF feedback you would get a low
> hum
> > similar to mains hum coming through with your tx audio. You say there is
> > feedback - if you hold the mic as far awayas possible from the speaker
can
> > you actually hear yourself talking without any feedback? If so the
likely
> > hood is that there is a short either in the radio or in either the M/F
mic
> > socket. Can't see this being a major problem so don't worry too much -
> just
> > a case of isolating the cause.
> >
> > Good Luck
> >
> > --
> > Nathan D Higgins
> >
> > Website: http://nathan.link9.net/
> > Email: nathan[at]link9[dot]net
> > Hosting: http://www.link9.net
> > WAP: http://wap.link9.net
> > MSN: nathan[at]link9[dot]net
> >
> >
>
>