[AMRadio] DX 100 question
Jim Wilhite
w5jo at brightok.net
Sat Apr 23 17:44:49 EDT 2011
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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