[AMRadio] DX 100 question

Sat Apr 23 18:16:01 EDT 2011

Hi Jim,

Glad you got it working.

When you have yours neutralized do you get max output at plate current dip
and also a peak in grid current right at the same place on plate tuning?

I could never find that spot with neutralization.

Yes I tried moving the 10 meter coil too. It did make some difference in the
amount of drive. Still come up short unless the neutralization is
disconnected.

73
Gary K4FMX

> -----Original Message-----
> From: amradio-bounces at mailman.qth.net [mailto:amradio-
> bounces at mailman.qth.net] On Behalf Of Jim Wilhite
> Sent: Saturday, April 23, 2011 5:45 PM
> To: Discussion of AM Radio in the Amateur Service
> Subject: Re: [AMRadio] DX 100 question
> 
> Hey Gary,
> 
> Fiddle with the spacing on that final coil.  I only had 3.5 ma on 10
> meters in a previous DX 100 and by spacing it a bit better managed to
> get full scale out of it with the drive pot all the way to the right.
> (don't you just love that expression  :>).  I just finished with this
> one and it is neutralized too.  This one has vertical two stubs of solid
> wire, one by each tube then they are connected together and insulated
> wire is run back into the driver section input.  The insulated wire is
> wrapped about 3 turns around the bare wire connected between the
> variable cap and coil.  There is enough capacitive coupling to
> neutralize the finals.
> 
> The previous DX 100 had one wire attached to the left connector on the
> stator of the variable then run horizontally into the cage.  It pointed
> nearly at the RF choke.  I respaced the final coil on this one and have
> it showing 8 ma grid current with the knob open full and with 5 ma grid
> it is showing 240 ma. plate current and about 70 watts out.
> 
> So what you and Craig told me worked and I don't know what the deal is.
> I would bet someone found this coil somewhere in a previous repair and
> put it in.  I bought this transmitter for a friend who is having trouble
> seeing and am getting it going for him.  He likes 10 AM so I wanted to
> make it work there.
> 
> So it works fine now.  I just need to put PTT in and I am finished.
> Thanks again
> 
> 73
> 
> Jim/W5JO
> 
> 
> ----- Original Message -----
> From: "Gary Schafer" <garyschafer at comcast.net>
> To: "'Discussion of AM Radio in the Amateur Service'"
> <amradio at mailman.qth.net>
> Sent: Saturday, April 23, 2011 3:57 PM
> Subject: Re: [AMRadio] DX 100 question
> 
> 
> > Hi Jim,
> >
> > On My DX-100 I have trouble getting enough drive on 10 meters also. I
> > think
> > that it only provides 4 ma grid current if I remember.
> > The Apache drive control has to be cranked up all the way to make 5 ma
> > of
> > grid current on 10. There is way more than enough drive on the lower
> > bands.
> >
> > There was a modification for adding a neutralization stub latter on.
> > Mine
> > has it in there and you get less grid current with it. Without the
> > stub
> > there is more feed back and that gives an apparent grid current
> > increase and
> > of course max power out of the final is not at minimum plate current
> > and
> > grid current does not peak at max power out either.
> > But when the neutralization is close grid drive is marginal. At least
> > on
> > mine.
> >
> > The second tap on the coils does seem strange though.
> >
> > 73
> > Gary  K4FMX
> >
> >> -----Original Message-----
> >> From: amradio-bounces at mailman.qth.net [mailto:amradio-
> >> bounces at mailman.qth.net] On Behalf Of Jim Wilhite
> >> Sent: Saturday, April 23, 2011 4:41 PM
> >> To: Discussion of AM Radio in the Amateur Service
> >> Subject: Re: [AMRadio] DX 100 question
> >>
> >> Thank you Gary and Craig,
> >>
> >> Yes this has 11 meters on it but no separate tap for that band.  It
> >> uses
> >> the 10 meter coil and the tuning cap is varied a bit is all.  With
> >> that
> >> information I can rewind this one .  It is also 17 turns but tapped
> >> at 8
> >> 1/2 and 12 1/2 turns from the bandswitch.  That 2nd tap only leaves 5
> >> turns on the coil, not enough for 10.
> >>
> >> I have good grid drive on all band but 10 and I can fix the problem,
> >> I
> >> could make this work, but want it like the book so the next person
> >> will
> >> know what is going on.  Another odd thing is some one in this
> >> transmitter's previous life added a wafer behind the driver
> >> bandswitch.
> >> It was a break then make 7 position switch and they had moved the
> >> final
> >> coils tap points to it rather than the ceramic shorting switch
> >> designed
> >> for it.
> >>
> >> Strange stuff can be found it Heath equipment.
> >>
> >>
> >> ----- Original Message -----
> >> From: "Gary Schafer" <garyschafer at comcast.net>
> >> To: "'Discussion of AM Radio in the Amateur Service'"
> >> <amradio at mailman.qth.net>
> >> Sent: Saturday, April 23, 2011 3:09 PM
> >> Subject: Re: [AMRadio] DX 100 question
> >>
> >>
> >> > Hi Jim,
> >> >
> >> > The total turns on that coil are 17. it has the tap at 9 1/2 turns
> >> > from the
> >> > grid end. That leaves 8 turns on the 15 meter part of the coil.
> >> > The 10 meter part is wound tightly with the turns touching each
> >> > other.
> >> > On
> >> > the 15 meter part the turns are spaced at around 1/8 inch between
> >> > turns.
> >> > Actually the last turn on 10 meters near the tap is spaced out
> >> > about
> >> > 1/4
> >> > inch.
> >> >
> >> > I wonder if your DX-100 is an early model with 11 meters on it? Did
> >> > they
> >> > have a separate tap for 11 meters?
> >> >
> >> > 73
> >> > Gary  K4FMX
> >> >
> >> >> -----Original Message-----
> >> >> From: amradio-bounces at mailman.qth.net [mailto:amradio-
> >> >> bounces at mailman.qth.net] On Behalf Of Jim Wilhite
> >> >> Sent: Saturday, April 23, 2011 3:32 PM
> >> >> To: Discussion of AM Radio in the Amateur Service
> >> >> Subject: Re: [AMRadio] DX 100 question
> >> >>
> >> >> Thanks for looking Gary,
> >> >>
> >> >> Yes that is the plate coil of the driver, one end to the final
> >> >> grids
> >> >> and
> >> >> the other tied to two point on the bandswitch.  What has me going
> >> >> is
> >> >> the
> >> >> one in this DX 100 is 3/4" in diameter (same as yours) and has two
> >> >> taps
> >> >> rather than the one you have.  I didn't, and still don't, know
> >> >> were
> >> >> this
> >> >> coil came from.  I though the Apache used the two tap coil for 10
> >> >> and
> >> >> 15
> >> >> + part of 20, which the DX 100 didn't.
> >> >>
> >> >> Evidently I was wrong.  If you still have the transmitter where
> >> >> you
> >> >> can
> >> >> see, how many turns on the total coil?    I sure appreciate your
> >> >> help.
> >> >>
> >> >> 73
> >> >>
> >> >> Jim/W5JO
> >> >>
> >> >>
> >> >>
> >> >>
> >> >> ----- Original Message -----
> >> >>
> >> >>
> >> >> > Hi Jim,
> >> >> >
> >> >> > I have my Apache turned on its side right now so I can see the
> >> >> > coils
> >> >> > underneath. My DX100 is in the cabinet and buried under a bunch
> >> >> > of
> >> >> > stuff.
> >> >> >
> >> >> > The coil in the Apache has only 1 tap in the center. This is the
> >> >> > small
> >> >> > air
> >> >> > wound coil about 3/4 inch in diameter. Part of it is spread out.
> >> >> >
> >> >> > Is this the coil you are looking at?
> >> >> >
> >> >> > 73
> >> >> > Gary  K4FMX
> >> >> >
> >> >> >> -----Original Message-----
> >> >> >> From: amradio-bounces at mailman.qth.net [mailto:amradio-
> >> >> >> bounces at mailman.qth.net] On Behalf Of Jim Wilhite
> >> >> >> Sent: Saturday, April 23, 2011 11:54 AM
> >> >> >> To: AM Radio Discussion List
> >> >> >> Subject: [AMRadio] DX 100 question
> >> >> >>
> >> >> >> Hi all,
> >> >> >>
> >> >> >> I have a DX 100 that has the wrong coil in the driver plate
> >> >> >> circuit
> >> >> >> or
> >> >> >> at least it seems.  The one in it has two taps, which I believe
> >> >> >> is
> >> >> >> for
> >> >> >> an Apache, but I am not really sure.  The DX 100 version is
> >> >> >> supposed
> >> >> >> to
> >> >> >> have just one tap about midpoint.  The taps on this one is not
> >> >> >> as
> >> >> >> specified for the DX 100.
> >> >> >>
> >> >> >> What I would like to know is how many turns the coil for the DX
> >> >> >> 100
> >> >> >> has.
> >> >> >> I can redo this one if I know how many turns to wind.  Thanks
> >> >> >> for
> >> >> >> any
> >> >> >> help.
> >> >> >>
> >> >> >> Jim/W5JO
> >> >> >>
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