How do you test a toroid?
|
w1sfr <steverob@...>
The transforming toroids are pretty tricky to wind. Is there any way to test them to find out if you've done it correctly?
73 Steve
|
|
|
|
Donald Kelly
Hi Steve,
I assume you know the ultimate inductance of the coil you are winding. A handy tool to have is a L/C meter. Not all toroids are alike and it is always a good idea to measure. My guess is most of the guys have one of these.
This meter evolved from a homebrew project by Bill Carver, W7AAZ. A digital readout was added later for easier use. The original project is classic in its simplicity. It is also included in “Experimental Methods in RF Design” in the test gear chapter.
http://www.qsl.net/wm5z/cq199301b.pdf
My version is used all the time. You can see the ugly style board is very simple. The trick is in the calibration steps and having a precision calibrating capacitor.
http://forums.qrz.com/showthread.php?238952-A-Simple-Homebrew-L-and-C-Tester
Test gear is fun to build and a great way to get started in scratch projects.
Don K5UOS
From: 4sqrp@... [mailto:4sqrp@...] On Behalf Of w1sfr
Sent: Tuesday, March 26, 2013 11:18 AM To: 4sqrp@... Subject: [4sqrp] How do you test a toroid?
The transforming toroids are pretty tricky to wind. Is there any way to test them to find out if you've done it correctly?
|
|
|
|
Stephen Roberts <steverob@...>
Hi Don,
toggle quoted messageShow quoted text
Well I can't see spending $150 for an LC meter although it would be nice to have one. I'm not really a electronic tech by any means so it's really hard to justify the expense. And from a practical point of view, building one would take me forever but it certainly looks like a worthy project. In the end, I'm sure I'll just fire it up and see what happens which is my normal method of testing ;-) 73 Steve
On Mar 26, 2013, at 9:19 PM, Donald Kelly wrote:
|
|
|
|
Lee Mairs (SAG) <lmairs@...>
Check eBay.� The Chinese have an LC ESR meter that is about $25.�
Has good reviews and works great.
toggle quoted messageShow quoted text
73 de Lee KM4YY
On 3/27/2013 10:31 AM, Stephen Roberts
wrote:
|
|
|
|
chuck adams <chuck.adams.k7qo@...>
On 03/27/2013 01:50 PM, Lee Mairs (SAG)
wrote:
A few days ago on qrp-tech, some one recommended the following. I ordered one and will run some tests on it, but the fact that it does so much is appealing, especially the ESR since I haven't gotten around to homebrewing one and the bench queue is too long now.� :-) Maybe some one has already gotten the same model already. FYI chuck, k7qo
|
|
|
|
Bill Cromwell
On Wed, 2013-03-27 at 14:03 -0700, chuck adams wrote:
Hi, Requires PayPal and PayPal only. Other offers? 73, Bill KU8H
|
|
|
|
w1sfr <steverob@...>
I went ahead and ordered one. Free shipping from China for $25.
toggle quoted messageShow quoted text
73 Steve
--- In 4sqrp@yahoogroups.com, Bill Cromwell <wrcromwell@...> wrote:
|
|
|
|
John Lonigro
That reminds me. I've got an "Elsie" kit which measures either inductance or capacitance and displays it via CW. It doesn't seem to work, probably because I have yet to build the stupid thing!! Maybe I should put that near the top of my list of kits to build. I can't remember but it probably cost less than that Chinese meter. Its only advantage is it provides some CW practice while measuring your components.
toggle quoted messageShow quoted text
In answer to someone's question, the MFJ-259 can indeed measure inductance. As I recall, you put a 50 ohm resistor in series with an LC circuit, find where the SWR is 1.0, and then do a little math to calculate the inductance, assuming you accurately know the value of the capacitor. The appropriate equation is in the handbook (probably any edition) and the instructions are in the MFJ manual. The L and C need to produce resonance at a frequency covered by the MFJ-259. Don't try to measure that 2 Henry choke in your junk box! 72, John AA0VE
On 03/27/2013 06:37 PM, w1sfr wrote:
|
|
|
|
Rick Bennett
A "2 Henry Choke". That sounds like some sort of self defense move...
toggle quoted messageShow quoted text
----- Original Message -----
That reminds me. I've got an "Elsie" kit which measures either inductance or capacitance and displays it via CW. It doesn't seem to work, probably because I have yet to build the stupid thing!! Maybe I should put that near the top of my list of kits to build. I can't remember but it probably cost less than that Chinese meter. Its only advantage is it provides some CW practice while measuring your components. In answer to someone's question, the MFJ-259 can indeed measure inductance. As I recall, you put a 50 ohm resistor in series with an LC circuit, find where the SWR is 1.0, and then do a little math to calculate the inductance, assuming you accurately know the value of the capacitor. The appropriate equation is in the handbook (probably any edition) and the instructions are in the MFJ manual. The L and C need to produce resonance at a frequency covered by the MFJ-259. Don't try to measure that 2 Henry choke in your junk box! 72, John AA0VE On 03/27/2013 06:37 PM, w1sfr wrote:
------------------------------------ 4SQRP Website: http://4sqrp.com OzarkCon is coming April 5-6 in Branson, MO View Details at http://www.ozarkcon.com/index.phpYahoo! Groups Links
|
|
|
|
Rick Bennett
To further expand on this, the "MFJ-259B" version has a mode that reads inductance directly. It has an upper limit of 60 uH, but in this case it should work. You will need to make a connector with clip leads for the '259.
toggle quoted messageShow quoted text
Also Diz has a handy calculator for toroids on his web site: http://toroids.info/BN-61-2402.php de KC0PET, Rick
----- Original Message -----
That reminds me. I've got an "Elsie" kit which measures either inductance or capacitance and displays it via CW. It doesn't seem to work, probably because I have yet to build the stupid thing!! Maybe I should put that near the top of my list of kits to build. I can't remember but it probably cost less than that Chinese meter. Its only advantage is it provides some CW practice while measuring your components. In answer to someone's question, the MFJ-259 can indeed measure inductance. As I recall, you put a 50 ohm resistor in series with an LC circuit, find where the SWR is 1.0, and then do a little math to calculate the inductance, assuming you accurately know the value of the capacitor. The appropriate equation is in the handbook (probably any edition) and the instructions are in the MFJ manual. The L and C need to produce resonance at a frequency covered by the MFJ-259. Don't try to measure that 2 Henry choke in your junk box! 72, John AA0VE On 03/27/2013 06:37 PM, w1sfr wrote:
------------------------------------ 4SQRP Website: http://4sqrp.com OzarkCon is coming April 5-6 in Branson, MO View Details at http://www.ozarkcon.com/index.phpYahoo! Groups Links
|
|
|
|
Hey Guys:
toggle quoted messageShow quoted text
This is sorta on topic, at least from the original thread. The information is a Quote from Diz himself. "Double check T3. Should be 2 turns primary centertaped and 2 turns secondary. If yoo look at T3 from the right side of the board, you should see only 3 loops of wire in the holes plust the 2 wires coming out." This only describes one of the transformers, but it seems pretty clear? My problem was related to low power out put and I thought I had messed up this coil! Good luck 72 Johnny AC0BQ
On Wed, Mar 27, 2013 at 7:48 PM, Rick Bennett <kc0pet@...> wrote:
|
|
|
|
Hey Guys:
toggle quoted messageShow quoted text
This is sorta on topic, at least from the original thread. The information is a Quote from Diz himself. "Double check T3. Should be 2 turns primary centertaped and 2 turns secondary. If yoo look at T3 from the right side of the board, you should see only 3 loops of wire in the holes plust the 2 wires coming out." This only describes one of the transformers, but it seems pretty clear? My problem was related to low power out put and I thought I had messed up this coil! Good luck 72 Johnny AC0BQ
On Wed, Mar 27, 2013 at 7:48 PM, Rick Bennett <kc0pet@...> wrote:
|
|
|