EMRFD Message Archive 5429
Message Date From Subject 5429 2010-11-17 16:59:51 Kenneth Stringham 2n7000 Failure
an internal diode to protect the device against a high voltage kick back. This
was done because this device was designed for this specific service.
Ken - AE1X5431 2010-11-18 04:47:19 nm0s_qrp Re: 2n7000 Failure
There are two primary failure modes of these MOSFETs. The first is puncture of gate oxide by excessive gate voltage or ESD. The second is thermal failure caused by overheating. If the device has good drive, is not operated in the linear mode, has a current-limited load, and has external clamping of inductive currents, it should not break. If in doubt, put your finger5433 2010-11-18 10:45:48 Glen Re: 2n7000 Failure
that matter), the "built-in" diode doesn't protect much. A regular
diode across the relay coil prevents the 2N7000 drain from seeing any
kicks higher than the 0.8v diode drop ABOVE the relay's supply voltage.
This is far better protection for the transient kick you get when the
2N7000 turns off.
The built-in 2N7000's diode only protects by avalanche, and that's
somewhere above 60v, unspecified in the data sheets I've seen. If a 60v transient at the drain couples back (through Cdg) to the gate, you could break down the gate oxide, a comm5434 2010-11-18 15:18:52 R Wall Help, is anyone able to generate a s2p Touchstone file from a BPF ci
Is anyone able to generate a s2p Touchstone file for the attached BPF circuit. I want to compare it with the BPF as measured on a N2PK VNA.
Thanks,
Roderick Wall, vk3yc.
[Non-text portions of this message have been removed]5435 2010-11-19 07:07:39 ka7exm Re: Help, is anyone able to generate a s2p Touchstone file from a BP
The group posting did not carry along the attachment.
Can you please post the circuit model (text) in your reply and I can take a look at it for you.
Thanks & 73,
Roger
5441 2010-11-19 12:56:01 R Wall Re: Help, is anyone able to generate a s2p Touchstone file from a BP
Thanks very much for your help. Circuit is as below.
It’s great to have people5442 2010-11-19 13:09:58 R Wall Re: Help, is anyone able to generate a s2p Touchstone file from a BP
It didn’t get there so I uploaded it into the group’s file section. It’s called “40 meter BPF Circuit Diagram”
http://f1.grp.yahoofs.com/v1/UOXmTNHb-qNwBOu71BrxJM9eUyHfrxhX7kfCw6VcPpZGg667hqqgqGHyakiwyWwfdBqcA-KWcku_xW8DEWq-oQmxkUK1wKRBHZQoHONhCto/40%20meter%20BPF%20Circuit%20Diagram.jpg
Email address is: vk3bko (at) virginbroadband.com.au
Thanks for your help,
Roderick Wall, vk3yc.
5443 2010-11-20 09:04:27 wb6tpu Re: Help, is anyone able to generate a s2p Touchstone file from a BP
I ran your BPF through Ansoft Designer and generated a set of s-parameters for you.
The Touchstone file, a couple of S21 plots and a snapshot of the circuit schematic as analyzed in Designer can be found in the
40M_BPF_Sparams directory I just created in the group Files area.
Best 73's,
-Ray WB6TPU
5444 2010-11-20 12:18:21 R Wall Re: Help, is anyone able to generate a s2p Touchstone file from a BP
Thank’s very much for your help. I compared it with my built BPF, of course my BPF has more loss. I wonder if you’re able to do another s2p file but this time with inductor Q = 80 and Capacitance Q = 2k. Thanks very much for your help.
Roderick Wall, vk3yc.
5445 2010-11-20 13:46:07 wb6tpu Re: Help, is anyone able to generate a s2p Touchstone file from a BP
Sure, no problem. I'll post the results shortly.
-Ray WB6TPU
5446 2010-11-20 14:06:39 Lasse Re: Help, is anyone able to generate a s2p Touchstone file from a BP
look for BPF_Q80.s2p and the jpg for plots...
Cheers
Lasse SM5GLC
R Wall skrev 2010-11-20 21:18:
> Hi Ray,
>
> Thank’s very much for your help. I compared it with my built BPF, of course my BPF has more loss. I wonder if you’re able to do another s2p file but this time with inductor Q = 80 and Capacitance Q = 2k. Thanks very much for your help.
>
> Roderick Wall, vk3yc.5447 2010-11-20 14:15:37 wb6tpu Re: Help, is anyone able to generate a s2p Touchstone file from a BP
The new file with the Q assumptions have been placed in the same folder as the previous ones.
The new files have "_with_Q" appended to the filenames.
-Ray WB6TPU
5448 2010-11-20 17:03:31 R Wall Re: Help, is anyone able to generate a s2p Touchstone file from a BP
The results.
Insertion loss:
vk3cy DUT - 7.0MHz = 1.846 dB, 7.15MHz = 1.568 dB, 7.13MHz = 1.797 dB. Measured on my N2PK VNA.
wb6tpu – 7.0MHz = 1.996 dB, 7,15MHz = 1.667 dB, 7.13MHz = 1.805 dB.
Lesse – 7.0MHz = 2.087 dB, 7.15MHz = 1.683 dB, 7.3MHz = 1.723 dB.
I reck5449 2010-11-21 10:26:49 lasse moell Re: Help, is anyone able to generate a s2p Touchstone file from a BP
Still linear analysis is pretty basic and should give same result whatever software you use, even the free RFSim99 should give identical results! I just verified that it do suppport physical models i.e. real world Q. Why not give it a try yourself?
Cheers
Lasse
5450 2010-11-21 11:55:52 Tayloe Dan-P26412 Re: Help, is anyone able to generate a s2p Touchstone file from a BP
- Dan, N7VE
lasse moell <lasse.moell@swipnet.se> wrote:
I'm using Eagleware/Agilent Genesys... not really amateur stuff but have access though work :)
Still linear analysis is pretty basic and should give same result whatever software you use, even the free RFSim99 should give identical results! I just verified that it do suppport physical models i.e. real world Q. Why not give it a try yourself?
Cheers
Lasse
5451 2010-11-21 16:32:55 R Wall Re: Help, is anyone able to generate a s2p Touchstone file from a BP
I tried RFsim99 and it gave simular results. But I can’t export a s2p Touchstone file. Someone said that QU.... (can’t remember the name) will export snp files, I’ll download that and see what I get.
Thanks all for your help,
Roderick Wall, vk3yc.
5452 2010-11-21 16:56:44 ehydra Re: Help, is anyone able to generate a s2p Touchstone file from a BP
- Henry
--
ehydra.dyndns.info
R Wall schrieb:
> Hi Lasse,
>
> I tried RFsim99 and it gave simular results. But I can’t export a s2p Touchstone file. Someone said that QU.... (can’t remember the name) will export snp files, I’ll download that and see what I get.
>5453 2010-11-22 00:15:16 Neil Douglas Re: Help, is anyone able to generate a s2p Touchstone file from a BP
QUCS can import / export Touchstone files.
Regards
NeilD
G4SHJ
_____
5454 2010-11-22 01:47:48 R Wall Re: Help, is anyone able to generate a s2p Touchstone file from a BP
I’ve just downloaded and installed QUCS and trying to determine how to set up s-parameter simulation. I have the circuit in but have to work out to do the simulation part. I have the s parameter box/block there but think I have to put in some measurement points or ports or something but not sure.
Thanks,
Roderick.
5455 2010-11-22 07:03:06 lasse moell Re: Help, is anyone able to generate a s2p Touchstone file from a BP
Draw your circuit, and choose simulate. Under files your first item is save as s-parameter. Not sure if a bug, but you may have to change from diagram to data list, for the "Save s-parameter" to show up. Once shown it is there in all diagram types.
Had a quick look inside the s2p-file and it sure looks as it should!
Cheers
Lasse SM5GLC
5456 2010-11-22 07:33:19 ehydra Re: Help, is anyone able to generate a s2p Touchstone file from a BP
Correct: XL=2*PI*F*L
And the trick works only in small-bandwidth model.
regards -
Henry
--
ehydra.dyndns.info
Tayloe Dan-P26412 schrieb:
> The inductor loss can be modeled by placing a parallel resistance to
> the inductor of value of Q*XL. In other words if you have a Q of 200
> and 100 ohms (XL=2*PI*F) of inductive reactance, it looks like 20K of
> resistance loading the parallel tuned inductor. Then any of the free
> spice programs will readily analyze it. TI TINA or LT's LT Spice
> will do this no problem.
>
> - Dan, N7VE
>
> lasse moell <lasse.moell@swipnet.se> wrote:
>
> I'm using Eagleware/Agilent Genesys... not really amateur stuff but
> have access though work :) Still linear analysis is pretty basic and
> should give same result whatever software you use, even the free
> RFSim99 should give identical results! I just verified that it do
> suppport physical models i.e. real world Q. Why not give it a try
> yourself? Cheers Lasse
>
>5459 2010-11-22 11:41:27 wb6tpu Re: Help, is anyone able to generate a s2p Touchstone file from a BP
Since the schematic you provided of your BPF appears to have originated in Elsie, I was wondering if you knew that Elsie can output s-parameters of the filter?
To include the effects of Q you need to add extra series and shunt resistors as appropriate to define non-ideal C and L. With many other tools you can simply specify the element Q.
-Ray WB6TPU5460 2010-11-22 11:53:25 Jim Tonne Re: Help, is anyone able to generate a s2p Touchstone file from a BP
The S-parameter files generated by Elsie do indeed
take into account inductor and capacitor Q values.
Also, the outputs by Elsie for LTspice schematic files
have buried in them the associated resistors for
Q-determination.
- JimT
>
> Roderick-
>
> Since the schematic you provided of your BPF appears to have originated in
> Elsie, I was wondering if you knew that Elsie can output s-parameters of
> the filter?
> To include the effects of Q you need to add extra series and shunt
> resistors as appropriate to define non-ideal C and L. With many other
> tools you can simply > specify the element Q.
>
> -Ray WB6TPU
>5461 2010-11-22 12:10:48 wb6tpu Re: Help, is anyone able to generate a s2p Touchstone file from a BP
I guess I'm missing something. It wasn't obvious to me how to define a Q value for a C or L. Probably just cockpit error5462 2010-11-22 12:15:17 wb6tpu Re: Help, is anyone able to generate a s2p Touchstone file from a BP
Poor form to answer ones own post, but I just figured our where you specify the Q. (In the analysis tab, not the edit or schematic tab where I was expecting to find them.
thanks for pointing out the Q capability of your fine tool.
73's,
-Ray WB6TPU
5463 2010-11-22 12:21:23 R Wall Re: Help, is anyone able to generate a s2p Touchstone file from a BP
You are correct. You must use the “File” on the simulation window, not the “File”5464 2010-11-22 12:42:52 R Wall Re: Help, is anyone able to generate a s2p Touchstone file from a BP
Yes I did know that Elsie was now able to generate snp files. In fact I was also comparing Elsie’s s2p file to my DUT BPF and other s2p generated files to ensure they were the same.
Ok on adding resistors to reduce the Q on ideal C and L components.
Thanks all for your help,
Roderick, vk3yc.
5465 2010-11-22 19:47:15 R Wall Re: Help, is anyone able to generate a s2p Touchstone file from a BP
I have QUCS simulating the 40 meter BPF with the s parameter block. I can create a Tabular diagram with all the s-parameters that I want.
I’ve searched everywhere but can’t find out how I generate a s2p file from this.
Does anyone know.
Thanks,
Roderick Wall, vk3yc.
5466 2010-11-23 09:55:03 wb6tpu Re: Help, is anyone able to generate a s2p Touchstone file from a BP
After running your analysis, use the Import/Extract Data function found in the 'Project' drop-down menu.
Note that for this to work you need to define a Project and then add your schematic to that project with the add files command.
When you use the Import/Extract Data functi5467 2010-11-23 12:43:24 R Wall Re: Help, is anyone able to generate a s2p Touchstone file from a BP
Thanks very much for your help, I got it to work. QUCS is complex to use but gets easier the more you use it, seems to work well and it’s free.
Thanks for your help,
Roderick Wall, vk3yc.