That's what I did, 10nF added to the loop- var cap setup, and now I see
that RMC INfo on 216 comes in with sig 9... (without loop: about 1).

Strange thing is that with var cap + 10nF the loop only tunes between
say 207 and 225 khz, while on AM (without the 10nF), it tunes 1 MHz wide
...

explanation ??
I saw that some people make their own var cap ... (with very large
plates...)

Now, I intend to buy some nF caps from 1-50nF or so, to see what's
happening ...

Today I picked up two old grundigs, and after some tweaking (knobs) they
work !
melody boy 500 (excellent condition, the AM-FM- etc knobs aren't touched
....)
and a Yacht boy with lamp, batt indication, AFC ... tunes very well on
SW...
Great sound on both radios ...

---and now, for a great song: ---
http://www.asklyrics.com/display/Chu...rics/12119.htm
----
You're just an antenna, you're just a wire.
There's a thousand tongues wagging in your ears tonight,
And you turn around and you call me a liar.
Lightly babe, oh the fine lights cannot find you.
She stay out my way, it's the pulse I am aligned to.
And everything you say, you'll need that breath one day.
Well, you're just an antenna, you're just a code.
You translate like a book, the fuses all cook.
You eat humble pie and it tastes of the road.
Lightly babe, oh the fine lights cannot find you.
She say, that's the way, that's the fate I am resigned to.
And everything you say, you'll need that breath one day.
You're just an antenna, you're just a gauge.
You disturb my slumber and round up the numbers
And put them inside your velvety cage.
Lightly babe, oh the fine lights cannot find you.
She say, make my day, and the sunlight will not blind you.
Lightly babe, oh the fine lights cannot find you.
I may never pray to the fortune that's behind you.

--
een appeltje te schillen met http://applefaulty.be
http://users.fulladsl.be/spb13810/bwnl.htm
Breng je iMac G5 terug (ik wil binnen 2 jaar geen defecte 2de hands Apple kopen)
http://www.apple.com/nl/support/imac...ensionprogram/

On Fri, 05 May 2006 23:53:07 +0200, switcher
wrote:
Strange thing is that with var cap + 10nF the loop only tunes between
say 207 and 225 khz, while on AM (without the 10nF), it tunes 1 MHz wide
..

explanation ??

Your variable capacitor (probably in the 20 to 400pF range) is a small
percentage of the total capacitance when the 10nF is added to it.
Alone, and at a higher frequency, it is enough to cover that much
range.

I saw that some people make their own var cap ... (with very large
plates...)

Now, I intend to buy some nF caps from 1-50nF or so, to see what's
happening ...

Buy some 1-50nF? You may discover why others build them.

Today I picked up two old grundigs, and after some tweaking (knobs) they
work !
melody boy 500 (excellent condition, the AM-FM- etc knobs aren't touched
...)
and a Yacht boy with lamp, batt indication, AFC ... tunes very well on
SW...
Great sound on both radios ...

yes indeed.

---and now, for a great song: ---
http://www.asklyrics.com/display/Chu...rics/12119.htm

Chacun à son Goût!

73's
Richard Clark, KB7QHC

http://cgi.ebay.at/RARITAT-GRUNDIG-W...-TOP_W0QQitemZ
7614592587QQcategoryZ19693QQrdZ1QQcmdZViewItem#eba yphotohosting

this is the YB I found ... (I don't sell it, yet ... )

--
een appeltje te schillen met http://applefaulty.be
http://users.fulladsl.be/spb13810/bwnl.htm
Breng je iMac G5 terug (ik wil binnen 2 jaar geen defecte 2de hands Apple kopen)
http://www.apple.com/nl/support/imac...ensionprogram/

On Fri, 05 May 2006 23:53:07 +0200, switcher
wrote:

That's what I did, 10nF added to the loop- var cap setup, and now I see
that RMC INfo on 216 comes in with sig 9... (without loop: about 1).

Strange thing is that with var cap + 10nF the loop only tunes between
say 207 and 225 khz, while on AM (without the 10nF), it tunes 1 MHz wide
..

explanation ??
I saw that some people make their own var cap ... (with very large
plates...)

Now, I intend to buy some nF caps from 1-50nF or so, to see what's
happening ...

Today I picked up two old grundigs, and after some tweaking (knobs) they
work !
melody boy 500 (excellent condition, the AM-FM- etc knobs aren't touched
...)
and a Yacht boy with lamp, batt indication, AFC ... tunes very well on
SW...
Great sound on both radios ...

---and now, for a great song: ---
http://www.asklyrics.com/display/Chu...rics/12119.htm
----
You're just an antenna, you're just a wire.
There's a thousand tongues wagging in your ears tonight,
And you turn around and you call me a liar.
Lightly babe, oh the fine lights cannot find you.
She stay out my way, it's the pulse I am aligned to.
And everything you say, you'll need that breath one day.
Well, you're just an antenna, you're just a code.
You translate like a book, the fuses all cook.
You eat humble pie and it tastes of the road.
Lightly babe, oh the fine lights cannot find you.
She say, that's the way, that's the fate I am resigned to.
And everything you say, you'll need that breath one day.
You're just an antenna, you're just a gauge.
You disturb my slumber and round up the numbers
And put them inside your velvety cage.
Lightly babe, oh the fine lights cannot find you.
She say, make my day, and the sunlight will not blind you.
Lightly babe, oh the fine lights cannot find you.
I may never pray to the fortune that's behind you.
written by Roderick Taylor
© 1976 Rat's God Music (BMI)

Oh what a sunny day
When they carried the radio home
Bringing him in off of the truck
And the dogs wouldn't leave us alone
Mr. Radio
Come down here to keep us company

We listen in a room
Through the miles and miles of night
Deep in the heart of the Bible Belt
In the golden radio light
Mr. Radio
Come down here to keep us company

And it's hard days out in the field
The crows in the high tree top
If the man's away from his home all day
His chickens might fall to the fox
Mr. Radio
What can you do about that uh huh

And you can take me down to a river town
Where the citizens dance till dawn
Dance so close it's a sin almost
The way they carry on
Mr. Radio
I never dreamed you could

And it's miles at the careless touch
Of a tired hand in time
When evening fell I heard a stranger sell
Dreams that were never mine
Mr. Radio
Come down here to keep us company
Come down here to keep us company

Well, if he does cover 207-225 w/ a fixed 10nF in parallel with
whatever tuning cap he has, that implies Cmax/Cmin = (225/207)^2 =
1.18/1. Since Cmin is at least 10nF, the variable to accomplish that
must be 1800pF, at least. That in itself is a pretty good size
variable cap.

Then the implication would be that L = 50uH, and 1800pF would tune that
to 530kHz. The minimum capacitance including stray and effecitve coil
shunt would be 175pF to tune to 1700kHz.

I think he means to buy some fixed caps in the range 1-50nF, not a
1-50nF variable. (Though in this forum, maybe he does mean the
variable!) The fixed caps could make some sense. Maybe put them on
dual stackable banana plugs, and plug together whatever value is
desired.

Switcher, you can do the calcs yourself: 2*pi*freq = 1/sqrt(L*C) --
or use something like the RF calculator that's in RFSim99. And you may
find it's better to not try to cover too wide a range with one loop by
adjusting only the capacitance, for performance reasons in addition to
the fact that the tuning range will get very small as you go to larger
fixed capacitances.

Cheers,
Tom

In article ,
switcher wrote:

That's what I did, 10nF added to the loop- var cap setup, and now I see
that RMC INfo on 216 comes in with sig 9... (without loop: about 1).

Strange thing is that with var cap + 10nF the loop only tunes between
say 207 and 225 khz, while on AM (without the 10nF), it tunes 1 MHz wide
..

explanation ??

Snip

Your tuning cap at the low range is only part of the total capacitance
instead of the whole capacitance for the resonant circuit. I have those
duh moments too.

--
Telamon
Ventura, California

K7ITM wrote:

I think he means to buy some fixed caps in the range 1-50nF, not a
1-50nF variable. (Though in this forum, maybe he does mean the
variable!) The fixed caps could make some sense. Maybe put them on
dual stackable banana plugs, and plug together whatever value is
desired.


You could use a solid state analog mux IC to switch capacitors at
those frequencies. Maxim, Analog Devices and others make a wide
selection of these chips.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

"Richard Clark" wrote in message
...
On Sat, 06 May 2006 08:35:28 +0200, switcher
wrote:

Yes, I would buy fixed, of course, they have them in eu at www.conrad.fr

Make sure they exhibit low ESR (Equivalent Series Resistance). Not
all capacitors are especially suitable for tuning.

73's
Richard Clark, KB7QHC

Don't use the cheap ceramic capacitors that are meant to be used for
bypassing. A friend of mine used some in a tuned circuit, and he got a
distorted sine wave output. In addition to possibly high ESR, the value of
these capacitors changes with the instantaneous applied voltage. To be safe,
use caps with mica or plastic dielectric.

Tam

switcher wrote:

The loop is 2 x 3 meter of PVC tube, bended in a circle.
There are now 3 turns. Guess ... how many turns to have the LW
153-279khz ???

If 3 turns resonated with about 11000 pF (your 10 nF plus about 1 nF
from the tuning capacitor) produces a resonance within that band, then
raising the turns to about 9 (3 times as much for about 3^2 times as
much inductance) would resonate at the same frequency with about 1/9th
as much capacitance (same L*C product). Of course, those extra turns
will also add quite a bit of stray capacitance between turns, so you
may not be able to reach the top of the band at minimum tuning
capacitance.

What kind of insulation is on the wire in the big loop? Its thickness
and dielectric constant have a big effect on the total stray
capacitance each turn will add.

switcher wrote:
In article ,
John Popelish wrote:
(snip)
What kind of insulation is on the wire in the big loop? Its thickness
and dielectric constant have a big effect on the total stray
capacitance each turn will add.


I guess copper 0.7 mm, insulation soft plastic .25 mm

Sounds like ordinary PVC insulated hook up wire. The PVC is a little
lossy, but not too bad at this low frequency. You would have a lot
more trouble with high capacitance if you were using enameled (magnet)
wire. My favorite for such things is Teflon or Tefzel insulated wire
(low loss and low dielectric constant), but it is expensive and hard
to find. Another good, but hard to find insulation is polyethylene.
It is sometimes used in low capacitance, data grade cables, but
stripping out enough for this project would be a career.

Do you think it is practical to pull 6 more turns through your pipe?