Electronics > Projects, Designs, and Technical Stuff
5uH Aerospace LISN: How dumb would I be to "throw one together"?
Jay_Diddy_B:
Hi,
The SER1590 inductors look like they will work. They may be slightly low on saturation compared to some of the other parts. The price is right.
The 10uF feed-thru capacitor is bit harder. This is what the 'official' parts look like:
I found three manufacturers of these but they all looked similar.
I found this listing:
http://www.icwltd.co.uk/products/ft.php
They show this style:
I don't really know much about the RF performance of these capacitors.
I would be tempted to try 10 pieces of a PHE850ER7100MR03R06L2 from Kemet. These are Y2 rated.
This would be one of the two LISNs:
I included the larger SER2918 Inductors.
I did not place the parts in the transient limiter.
Regards,
Jay_Diddy_B
TimNJ:
Just did a sanity check on the Coilcraft Model...The SFR is not showing at all. Might explain why it's so flat...although 115MHz SFR sounds good regardless. You're right about the saturation point. Perfect inductance is really only maintained to 10-12A which isn't a huge upgrade over a standard Tekbox model. On the other hand the SER2011/SER2013 series are bigger and more expensive. I'll think about it.
Here's the model. Not sure what everything is exactly. Wurth model in the same setup shows SFR just fine.
--- Quote ---.subckt SER1590-102_freq port1 port2 PARAMS: Cpar=27.7pF Ind=1uH
X1 port1 port2 Model1A PARAMS:
+ R1=535
+ R2=0.02
+ C= {Cpar}
+ K1=1E-09
+ K2=0.341
+ K3= {Ind}
+ K4=0.012
+ K5=0.00001
+ L=0
+ Is=0
+ a=0
+ L_Z0=0
+ L_EL=0
+ L_F0=0E6
+ PkZ=186.791125
.ends SER1590-102_freq
--- End quote ---
Regarding the 10uF capacitance...you are right that Y-class capacitors are technically appropriate here. I was looking for Y-class caps in large value today, but somehow did not come across this series, so I decided X2 might be okay for *laboratory use only*. The cost of Y2 film caps is very high, not to mention the size is enormous...close to 10x the size of X2.
I am definitely hesitant to say any of this on a public forum.
Warning to anyone reading: X-class capacitors are built to be safer than normal film capacitors, but still are not intended to go from line/neutral to earth. If a capacitors in that position fails, it has the potential to put the chassis at a high potential. X capacitors are not advised in the position I mentioned.
At the same time, for a properly earthed system, an internal short to earth should blow the internal or building fuse/breaker. I'm a little bit on the fence.
TimNJ:
This doesn't necessarily make it right but the Tekbox TBLC08 LISN (teardown EEVBlog #993) uses Vishay MKP1847
https://www.vishay.com/docs/28172/mkp1847ac.pdf
...not even X2. Just a normal film cap.
The LISN at work (Atten brand) also only uses X2 capacitors. I wonder what a Rhode and Schwarz uses.
T3sl4co1l:
Honestly, I'd feel safer with MOVs on the mains side, and regular whatever-voltage-rated caps in the network, not X or Y. 630V or up is probably a reasonable choice.
Also, at some point we went from happy little DC LISNs, to mains LISNs. Probably better to make one specific to each, so you don't have these problems with scale. (The mains one probably won't do so well above 30MHz, either.)
The Coilcraft model can be plotted here, and also converted into a format usable in any SPICE engine:
https://www.seventransistorlabs.com/Calc/Coilcraft1.html
Ahh fuck, they updated their website, didn't they. All my links are broken... :rant:
These are the parameters required: https://www.coilcraft.com/en-us/models/spice/ I don't know what the other parameters are, in the above post.
Tim
TimNJ:
Thanks. Any reason not to use X-class?
Sorry if it wasn't clear but I think I stated that it was an AC (115V/400Hz) + DC (14V/28V) LISN from the start, but maybe that's buried in the mounds of text now in this thread.. In my case, I'll be using an isolated programmable AC source to produce the 400Hz (Chroma 61503) and an isolated supply for the DC. So...maybe not mains in that sense since there's some isolation.
I guess you're just talking about issues >30MHz due to sizes of parts for the mains rated version, if there was one? I agree it would probably make sense. Unfortunately, don't have a ton of time so I'd really rather only have one...if it was "good enough".
Thanks for pointing to your website, shall give it a look.
Thanks again.
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