[AMRadio] DX 100 question
Jim Wilhite
w5jo at brightok.net
Sat Apr 23 22:46:58 EDT 2011
Hello Gary,
The answer to your questions about the plate current dip and max power,
yes on 10 meters I do see that. The tune up procedure I follow is put
the meter in Grid and peak the tune knob. Then put the meter in Plate
and tune for proper current, 240 ma. Then I return the meter switch to
grid and repeak the grid tuning. After all this, the max power is at
the peak plate current and the grid reading is at its peak.
Something I forgot to mention is be sure those two coils that are the
grid input to the 5763 are tuned for max. I tuned up the rig on
frequency then put my scope probe on the grids of the finals and tuned
them for max. The one closest to the driver plate coil is adjusted on
10 meters and the other is adjusted on 15, if I remember right. I
always have to check that.
The rig is stable on all frequencies and I have plenty of grid drive on
all bands. I see 100 watts out on 160, 75,and 40, then about 90 on 20
and 70 or so on 15 and 10. I like the DX 100. It has very good parts
and is stable and very basic. It is a very easy transmitter to repair
except for that knob that moves the VFO. It is the pits to get on when
you put it back. This one has had the output cap modification made so I
don't have to fool with the step switch.
For those of you who aren't aware, Glen Zook, K9STH makes replacement
knobs for the DX 100, 60, 40, including that little red knob the is
always broken plus the concentric knob behind it. He also sells the
dial scale for the VF-1 and DX 100. They are reasonably priced but if
you buy the complete set, it will knock a hole in your pocketbook like
everything any more.
73
Jim
----- 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 5:16 PM
Subject: Re: [AMRadio] DX 100 question
> 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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