Reply by whit3rd April 29, 20132013-04-29
On Thursday, April 4, 2013 11:43:32 AM UTC-7, amdx wrote:

> No, the FET input stage, want to connect it to a high Q circuit and > have it look as if nothing is connected.
It's possible to position a small probe coil (with a low-Z preamplifier) so that it intercepts some very small flux from an RF coil. If the coupling is kept small, it looks like nothing is connected. Because, nothing is connected. Gain is cheap.
Reply by Jon Kirwan April 4, 20132013-04-04
On Thu, 04 Apr 2013 13:43:32 -0500, amdx
<amdx@knologynotthis.net> wrote:

><snip> > No, the FET input stage, want to connect it to a high Q circuit and >have it look as if nothing is connected. ><snip>
Oh. Well, I'm weak at JFET design -- especially 1st stage. But I'll think about it. The main reason that jumps out at me for why the JFET is used here is about noise. The only current noise in a JFET comes from the shot noise due to leakage currents, which are very low. The voltage noise is Johnson noise due to the channel resistance. Only at very high source impedances (which is the case on that page) does a good JFET beat out a good BJT. But as I said I'm not experienced with first stage JFET design issues and I need to think a bit about that part of the circuit before responding. Jon
Reply by amdx April 4, 20132013-04-04
On 4/4/2013 1:25 PM, Jon Kirwan wrote:
> On Thu, 04 Apr 2013 07:27:17 -0500, amdx > <amdx@knologynotthis.net> wrote: > >> On 4/3/2013 12:54 PM, Jon Kirwan wrote: >>> On Wed, 03 Apr 2013 10:53:24 -0500, amdx <amdx@knology.net> >>> wrote: >>> >>>> On 4/2/2013 2:04 PM, Jon Kirwan wrote: >>>>> On Sun, 31 Mar 2013 14:15:02 -0700, I wrote: >>>>> >>>>>> Left me worried, mikek. Was my explanation too poor to get >>>>>> the idea across? >>>>> >>>>> I guess so. Is there anything you may want to ask about, >>>>> then? >>>>> >>>>> Jon >>>>> >>>> >>>> Things for your info, I printed it out, it's on my bench waiting for >>>> me. I'm playing catch up at work, we're starting our busy season. >>>> One thing I'm pondering, the circuit I have is close to Version 2 >>>> about 1/2 way down this page. As you will note, the input wiring will >>>> have capacitance to the case, how can I best eliminate that? >>>> >>>> I think I need to build the second unit, so I can use KLeijer's >>>> method. Check Q with the first amplifier, connect the second amp with >>>> first still connected then retest* Q see if it lowers the Q. >>>> >>>> Mikek >>>> >>>> *using measurement data from first amp. >>> >>> Are you talking about the FET amplifier fro measuring LC >>> circuits? (I'm sorry it's not clear to me which page to look >>> at.) >>> >>> By the way, this page: >>> http://www.crystal-radio.eu/enlctest2.htm >>> >>> Shows some coil forms that would be trivial to make with my >>> 3D printer. In fact, I could probably make quite a variety of >>> coil formers of various kinds. That's a service I never even >>> considered before, but would be very easy to offer and >>> deliver on. Hmm. >>> >>> Jon >>> >> Here's the amp that he uses. http://www.crystal-radio.eu/enfetamp.htm >> >> As a test, he adds a second amp to see how it affects the measurement of >> the first amp. >> >> http://www.crystal-radio.eu/enfetamp.htm > > I'd looked at it. Were you looking for an analysis of the BJT > stage? (In effect, the 1k2 looks like a very high impedance > to AC. But not to DC. So start there.) >
No, the FET input stage, want to connect it to a high Q circuit and have it look as if nothing is connected.
>> Can you print polypropylene? That is one of the better low loss materials. >> An entrepreneur is born. > > Probably could. Supposedly, according to wiki, a "perfectly > isotactic PP" has a melting point of 171C. Which is well > within range of my 3D printer. All the rest of the types melt > even lower still, so even easier. What I'd need is filament > wire of it at 1.75mm diameter, though. > >> Here's a 3D coil I built with polystyrene. This was first iteration, >> then I lost access to my mill. The next was planned to be 600/46 litz, >> Now I've lost interest in the 3D unit. This was based on Kleijers design. >> >> http://i395.photobucket.com/albums/pp37/Qmavam/3DPolyHepwith24wire.jpg > > Yeah, I could build that thing. > > Jon >
Reply by Jon Kirwan April 4, 20132013-04-04
On Thu, 04 Apr 2013 07:27:17 -0500, amdx
<amdx@knologynotthis.net> wrote:

>On 4/3/2013 12:54 PM, Jon Kirwan wrote: >> On Wed, 03 Apr 2013 10:53:24 -0500, amdx <amdx@knology.net> >> wrote: >> >>> On 4/2/2013 2:04 PM, Jon Kirwan wrote: >>>> On Sun, 31 Mar 2013 14:15:02 -0700, I wrote: >>>> >>>>> Left me worried, mikek. Was my explanation too poor to get >>>>> the idea across? >>>> >>>> I guess so. Is there anything you may want to ask about, >>>> then? >>>> >>>> Jon >>>> >>> >>> Things for your info, I printed it out, it's on my bench waiting for >>> me. I'm playing catch up at work, we're starting our busy season. >>> One thing I'm pondering, the circuit I have is close to Version 2 >>> about 1/2 way down this page. As you will note, the input wiring will >>> have capacitance to the case, how can I best eliminate that? >>> >>> I think I need to build the second unit, so I can use KLeijer's >>> method. Check Q with the first amplifier, connect the second amp with >>> first still connected then retest* Q see if it lowers the Q. >>> >>> Mikek >>> >>> *using measurement data from first amp. >> >> Are you talking about the FET amplifier fro measuring LC >> circuits? (I'm sorry it's not clear to me which page to look >> at.) >> >> By the way, this page: >> http://www.crystal-radio.eu/enlctest2.htm >> >> Shows some coil forms that would be trivial to make with my >> 3D printer. In fact, I could probably make quite a variety of >> coil formers of various kinds. That's a service I never even >> considered before, but would be very easy to offer and >> deliver on. Hmm. >> >> Jon >> > Here's the amp that he uses. http://www.crystal-radio.eu/enfetamp.htm > >As a test, he adds a second amp to see how it affects the measurement of >the first amp. > >http://www.crystal-radio.eu/enfetamp.htm
I'd looked at it. Were you looking for an analysis of the BJT stage? (In effect, the 1k2 looks like a very high impedance to AC. But not to DC. So start there.)
>Can you print polypropylene? That is one of the better low loss materials. > An entrepreneur is born.
Probably could. Supposedly, according to wiki, a "perfectly isotactic PP" has a melting point of 171C. Which is well within range of my 3D printer. All the rest of the types melt even lower still, so even easier. What I'd need is filament wire of it at 1.75mm diameter, though.
>Here's a 3D coil I built with polystyrene. This was first iteration, >then I lost access to my mill. The next was planned to be 600/46 litz, >Now I've lost interest in the 3D unit. This was based on Kleijers design. > > http://i395.photobucket.com/albums/pp37/Qmavam/3DPolyHepwith24wire.jpg
Yeah, I could build that thing. Jon
Reply by amdx April 4, 20132013-04-04
On 4/4/2013 7:27 AM, amdx wrote:
> On 4/3/2013 12:54 PM, Jon Kirwan wrote: >> On Wed, 03 Apr 2013 10:53:24 -0500, amdx <amdx@knology.net> >> wrote: >> >>> On 4/2/2013 2:04 PM, Jon Kirwan wrote: >>>> On Sun, 31 Mar 2013 14:15:02 -0700, I wrote: >>>> >>>>> Left me worried, mikek. Was my explanation too poor to get >>>>> the idea across? >>>> >>>> I guess so. Is there anything you may want to ask about, >>>> then? >>>> >>>> Jon >>>> >>> >>> Things for your info, I printed it out, it's on my bench waiting for >>> me. I'm playing catch up at work, we're starting our busy season. >>> One thing I'm pondering, the circuit I have is close to Version 2 >>> about 1/2 way down this page. As you will note, the input wiring will >>> have capacitance to the case, how can I best eliminate that? >>> >>> I think I need to build the second unit, so I can use KLeijer's >>> method. Check Q with the first amplifier, connect the second amp with >>> first still connected then retest* Q see if it lowers the Q. >>> >>> Mikek >>> >>> *using measurement data from first amp. >> >> Are you talking about the FET amplifier fro measuring LC >> circuits? (I'm sorry it's not clear to me which page to look >> at.) >> >> By the way, this page: >> http://www.crystal-radio.eu/enlctest2.htm >> >> Shows some coil forms that would be trivial to make with my >> 3D printer. In fact, I could probably make quite a variety of >> coil formers of various kinds. That's a service I never even >> considered before, but would be very easy to offer and >> deliver on. Hmm. >> >> Jon >> > Here's the amp that he uses. http://www.crystal-radio.eu/enfetamp.htm > > As a test, he adds a second amp to see how it affects the measurement of > the first amp. > > http://www.crystal-radio.eu/enfetamp.htm > > Can you print polypropylene? That is one of the better low loss materials. > An entrepreneur is born. > > Here's a 3D coil I built with polystyrene. This was first iteration, > then I lost access to my mill. The next was planned to be 600/46 litz, > Now I've lost interest in the 3D unit. This was based on Kleijers design. > > Mikek
Dang, keep forgetting my links. http://i395.photobucket.com/albums/pp37/Qmavam/3DPolyHepwith24wire.jpg
Reply by amdx April 4, 20132013-04-04
On 4/3/2013 12:54 PM, Jon Kirwan wrote:
> On Wed, 03 Apr 2013 10:53:24 -0500, amdx <amdx@knology.net> > wrote: > >> On 4/2/2013 2:04 PM, Jon Kirwan wrote: >>> On Sun, 31 Mar 2013 14:15:02 -0700, I wrote: >>> >>>> Left me worried, mikek. Was my explanation too poor to get >>>> the idea across? >>> >>> I guess so. Is there anything you may want to ask about, >>> then? >>> >>> Jon >>> >> >> Things for your info, I printed it out, it's on my bench waiting for >> me. I'm playing catch up at work, we're starting our busy season. >> One thing I'm pondering, the circuit I have is close to Version 2 >> about 1/2 way down this page. As you will note, the input wiring will >> have capacitance to the case, how can I best eliminate that? >> >> I think I need to build the second unit, so I can use KLeijer's >> method. Check Q with the first amplifier, connect the second amp with >> first still connected then retest* Q see if it lowers the Q. >> >> Mikek >> >> *using measurement data from first amp. > > Are you talking about the FET amplifier fro measuring LC > circuits? (I'm sorry it's not clear to me which page to look > at.) > > By the way, this page: > http://www.crystal-radio.eu/enlctest2.htm > > Shows some coil forms that would be trivial to make with my > 3D printer. In fact, I could probably make quite a variety of > coil formers of various kinds. That's a service I never even > considered before, but would be very easy to offer and > deliver on. Hmm. > > Jon >
Here's the amp that he uses. http://www.crystal-radio.eu/enfetamp.htm As a test, he adds a second amp to see how it affects the measurement of the first amp. http://www.crystal-radio.eu/enfetamp.htm Can you print polypropylene? That is one of the better low loss materials. An entrepreneur is born. Here's a 3D coil I built with polystyrene. This was first iteration, then I lost access to my mill. The next was planned to be 600/46 litz, Now I've lost interest in the 3D unit. This was based on Kleijers design. Mikek
Reply by Jon Kirwan April 3, 20132013-04-03
On Wed, 03 Apr 2013 10:53:24 -0500, amdx <amdx@knology.net>
wrote:

>On 4/2/2013 2:04 PM, Jon Kirwan wrote: >> On Sun, 31 Mar 2013 14:15:02 -0700, I wrote: >> >>> Left me worried, mikek. Was my explanation too poor to get >>> the idea across? >> >> I guess so. Is there anything you may want to ask about, >> then? >> >> Jon >> > > Things for your info, I printed it out, it's on my bench waiting for >me. I'm playing catch up at work, we're starting our busy season. > One thing I'm pondering, the circuit I have is close to Version 2 >about 1/2 way down this page. As you will note, the input wiring will >have capacitance to the case, how can I best eliminate that? > > I think I need to build the second unit, so I can use KLeijer's >method. Check Q with the first amplifier, connect the second amp with >first still connected then retest* Q see if it lowers the Q. > > Mikek > >*using measurement data from first amp.
Are you talking about the FET amplifier fro measuring LC circuits? (I'm sorry it's not clear to me which page to look at.) By the way, this page: http://www.crystal-radio.eu/enlctest2.htm Shows some coil forms that would be trivial to make with my 3D printer. In fact, I could probably make quite a variety of coil formers of various kinds. That's a service I never even considered before, but would be very easy to offer and deliver on. Hmm. Jon
Reply by amdx April 3, 20132013-04-03
On 4/3/2013 10:53 AM, amdx wrote:
> On 4/2/2013 2:04 PM, Jon Kirwan wrote: >> On Sun, 31 Mar 2013 14:15:02 -0700, I wrote: >> >>> Left me worried, mikek. Was my explanation too poor to get >>> the idea across? >> >> I guess so. Is there anything you may want to ask about, >> then? >> >> Jon >> > > Things for your info, I printed it out, it's on my bench waiting for > me. I'm playing catch up at work, we're starting our busy season. > One thing I'm pondering, the circuit I have is close to Version 2 > about 1/2 way down this page. As you will note, the input wiring will > have capacitance to the case, how can I best eliminate that? > > I think I need to build the second unit, so I can use KLeijer's > method. Check Q with the first amplifier, connect the second amp with > first still connected then retest* Q see if it lowers the Q. > > Mikek > > *using measurement data from first amp.
Forgot to add link, http://www.crystal-radio.eu/index.html
Reply by amdx April 3, 20132013-04-03
On 4/2/2013 2:04 PM, Jon Kirwan wrote:
> On Sun, 31 Mar 2013 14:15:02 -0700, I wrote: > >> Left me worried, mikek. Was my explanation too poor to get >> the idea across? > > I guess so. Is there anything you may want to ask about, > then? > > Jon >
Things for your info, I printed it out, it's on my bench waiting for me. I'm playing catch up at work, we're starting our busy season. One thing I'm pondering, the circuit I have is close to Version 2 about 1/2 way down this page. As you will note, the input wiring will have capacitance to the case, how can I best eliminate that? I think I need to build the second unit, so I can use KLeijer's method. Check Q with the first amplifier, connect the second amp with first still connected then retest* Q see if it lowers the Q. Mikek *using measurement data from first amp.
Reply by Jon Kirwan April 2, 20132013-04-02
On Sun, 31 Mar 2013 14:15:02 -0700, I wrote:

>Left me worried, mikek. Was my explanation too poor to get >the idea across?
I guess so. Is there anything you may want to ask about, then? Jon