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Re: Weather resistant, covered Litz wire wanted.

 

¿ªÔÆÌåÓý

Am 06.12.2020 um 02:43 schrieb Kuba Ober:
There¡¯s probably some lore that perpetuates the ¡°RF is black magic¡± thing, and all sorts of myths get accepted into such lore. That¡¯s the thing about disjoint knowledge: people may say ¡°PVC is high loss¡± but they don¡¯t know what are the practical implications of it, they only may have heard it said in relation to an antenna or another ¡°incomprehensible¡± object, and the link from that bit of ¡°fact¡± to everyday life just isn¡¯t there.

There is a very nice Starlink customer terminal tear down video on YouTube (that device is a brilliant bit of engineering BTW) and a good vuunk of the comment section just goes to show that magical thinking is here to stay.

Cheers, Kuba



Polyvinylchlorid (PVC-U)
Allgemeine Eigenschaften
Werkstoffnummer
2690
Dielektrischer Verlustfaktor 1 MHz IEC 60250 300
Durchschlagfestigkeit IEC 60243-1 40
Dicke f¨¹r Durchschlagfestigkeit
0,6


Polypropylen Homopolymer (PP-H)
Allgemeine Eigenschaften
Werkstoffnummer
1502
Dielektrischer Verlustfaktor 50 Hz IEC 60250 2,5
Dielektrischer Verlustfaktor 1 MHz IEC 60250 3,5
Durchschlagfestigkeit IEC 60243-1 50


Tabelle 18: Zusammenfassung der Eigenschaften von PTFE, FEP und PFA
Eigenschaften Spezifikationen (ASTM) FEP
Dielektrizit?tskonstante D 150 bei 106 Hz 2,1
Dielektrischer Verlustfaktor D 150 bei 103 Hz 0,0001
Dielektrischer Verlustfaktor D 150 bei 106 Hz 0,0008
Durchschlagsfestigkeit D 149 2000

Re: 8590B power supply repair

 

Hi Mark,

Ok, noted.? Thanks.

Tom

On 12/5/2020 4:04 PM, Mark Bielman wrote:
Hi Tom,

I am not familiar w/this supply (assume it's NOT from HP) but I would have input diode rectifiers handy (single or bridge) as well as MOSFET's that drive the transformer.
Hope you have a variable AC supply for testing! Good luck.

Mark
Re: Weather resistant, covered Litz wire wanted.

 

A bit like Mary Poppins: Practically perfect in every way.

-Chuck Harris

donald collie wrote:
Can anybody comment on how well Teflon weathers?
Re: Weather resistant, covered Litz wire wanted.

 

Bruce : I`m trying to resonate this loop over the HF band, but it may be necessary to switch out turns with a relay etc. I plan to use the loop in its non-resonant mode, then resonate it to produce more output.
Sam : Rainer has Teflon sheathed Litz wire available - nice stuff.
OK on dielectric loss of PVC vs PE. Can anybody comment on how well Teflon weathers?

Virus-free.

On Sun, Dec 6, 2020 at 2:52 PM Sam Reaves <sam.reaves@...> wrote:
Could you just put regular Litz wire in teflon tubing?


Virus-free.

Re: 8590B power supply repair

 

Tom,

Send me a PM and I'll send info that I have.

W3OHM
Re: Weather resistant, covered Litz wire wanted.

 

Could you just put regular Litz wire in teflon tubing?
Re: Weather resistant, covered Litz wire wanted.

 

There¡¯s probably some lore that perpetuates the ¡°RF is black magic¡± thing, and all sorts of myths get accepted into such lore. That¡¯s the thing about disjoint knowledge: people may say ¡°PVC is high loss¡± but they don¡¯t know what are the practical implications of it, they only may have heard it said in relation to an antenna or another ¡°incomprehensible¡± object, and the link from that bit of ¡°fact¡± to everyday life just isn¡¯t there.

There is a very nice Starlink customer terminal tear down video on YouTube (that device is a brilliant bit of engineering BTW) and a good vuunk of the comment section just goes to show that magical thinking is here to stay.

Cheers, Kuba

5 dec. 2020 kl. 9:16 fm skrev Chuck Harris <cfharris@...>:

?Ordinary PVC is very, very low loss through low microwave frequencies, as is
easily demonstrated by putting a piece in your microwave oven.

Do you have a reference I can look at that shows your assertion?

-Chuck Harris

Andy ZL3AG via groups.io wrote:

Depending on the frequency, PVC's loss tangent will ruin your loop Q, so try to use
HDPE or LDPE instead.

Possible source of litz wire can be transformers used in high efficiency SMPS's, but
the ideal litz wire (wire thickness and qty of wires) changes, even across the MW band.

If you want to build a kick-arse receive loop for MW, I highly recommend the late
Graham Maynard's "Sprial loop with Q multiplier" as found in Practical Wireless - the
best loop I've ever used (feeding into a Racal RA17L).
Re: WTB HP 8660C Module Extension Cables 11672

 

Hello
do you still have the extention cables .
11672-60001.
Please let me know
Thanks
Bob Levy
Re: 8590B low sensitivity problem

 

Martin,
?Two things:
Check your email for an email from me.?
Be very careful when checking anything in the input circuit with an ohmmeter. Don't make any measurements where the input mixer could be subjected to DC from an ohmmeter and beware of ESD. Either one of these could damage the mixer diodes.

73,
Sam
W3OHM
Re: Can capacitors

 

Go to https://www.tubesandmore.com/products/capacitors?filters=Brand%3DCE%20Manufacturing

They sell the CE Mfg can caps.

Dave
Re: Agilent 54831M

Bostonman
 

I have quite a few updates.

The external monitor I had was working. Yesterday I tried my (very) old PC to boot the original hard drive that was in the scope and noticed weird things with the monitor. It went from showing BIOS to suddenly acting weird after the initial boot screen.

In any case, I was able to find another monitor and now both, the scope and the old PC, display properly. I honestly don't know what happened to the monitor because it shows some screens, but not others, however, it was originally showing the screens that no longer work. In any case, let's forget all the display issues I was having and move onto booting issues.

Here is what I've tried with the scope (remember all the boards are removed and nothing is connected to the motherboard): the bare motherboard, the original RAM, a "new" stick of RAM in both the original slot and switched to the middle slot, cable slot IDE1 and IDE2, and a different IDE cable.

Here is what I tried with my old PC: I used the XP boot CD I made for the scope in the CD-ROM and the PC booted fine.

In all cases, the scope has basically consistent results. Using power from the PC (because it has a four-pin connector) to power the CD-ROM and the IDE cable from the scope, I booted the scope. In both IDE 1 and IDE2 I got a blue screen. The normal boot sequence is: the screen shows a horizontal progress line as it boots, then it shows Microsoft Corporation in small color print, and from there, I get the blue screen (on the scope) or a Windows basic desktop with the boot software options on the PC.

If I boot the scope with no drive connected, I get a 'disk boot failure' as I do if I try the original SSD.

This tells me something is wrong with the motherboard because I tried all variations as listed above. Unfortunately I can't get the original SSD hard drive to boot in my PC. It shows the same jumbled name (S;nDirk...) as when it's in the scope.

The final results are: the CD that boots fine in the PC doesn't boot in the scope (same CD-ROM, same power source, different IDE cable, but I tried two cables.The original SSD in the scope doesn't boot in the PC; nor does a 5.25" drive I extracted an image to (but forget which image I used - whether it was from the SSD or the one from the previous owner who imaged the drive before replacing it with the SSD).

Attached are several pictures for a visual of which screens I saw.

IMG_8174.jpg
IMG_8176.jpg
IMG_8274.jpg
IMG_8275.jpg
IMG_8273.jpg

Re: Weather resistant, covered Litz wire wanted.

 

This is why I love this site!!


On Sat, Dec 5, 2020, 3:01 PM John Lyles <jtml@...> wrote:
For a comparison of PVC versus PE (HDPE is just as good), the best source of dielectric loss mesurements is Von Hipples work from MIT, around WWII. Since you may not have his text book, can download the data from "Tables of Dielectric Materials" from , I think that's the Defense Technical Info Center. Google it, and Von Hipples name. Once you downloaded the PDF, look at page 116 for polyvinyl Chloride and page 153 for polyethylene. Dielectric constants for both are relatively similar. But look at loss tangent. At 1 MHz PVC is 0.016, PE is 0.0002. And you can see similar difference up to 10^7 (10 MHz) and 10^8 Hz. In RF heating (which is the effect that loss give), the loss tangent is directly related as is frequency. Electric field is a squared term. I would not recommend PVC insulation on anything that has high RF voltage in the MHz, unless you don't mind the loss and the part is cooled. Using PVC pieces as spiders for an open wire RF transmission line that is matched is probably OK, but not in a resonant circuit where the electric field rises. So it depends on the application. PVC is a very polar molecule like water, having a net dipole moment. These little dipoles are what causes the loss. Don't forget that a microwave oven at 2450 MHz has a low field strength as it is not a single resonant mode, in fact the fields are bouncing all around. When I worked for DuPont years ago, I was in the dielectric heating group. We would get chemists all the time saying "this stuff is great, I put in in my microwave oven and it only warmed in xx minutes." To which we would open the cover of our 90 Mhz WT LaRose heater with about 15 kV across the plates, and the PVC would catch on fire in 10-20 seconds. Believe me, I have done this dozens of times to prove out various hose and insulation materials in high power RF amplifiers in my workplace.

Re: Weather resistant, covered Litz wire wanted.

 

Hi John,

I guess the definition of bad varies depending on the task.

I had always heard that PVC wasn't great, but for most ordinary
tasks HF -> VHF, it would suffice. The hams have been touting
the microwave as a good way of testing dielectrics for loss, and
I am still not certain that it isn't.

I found a table of dielectric properties in an ITT Reference Data for
Radio Engineers Handbook, and it is interesting to see that the
properties of PVC are very similar to epoxy, as in FR4, and about
the same as nylon.

I am not yet willing to rule out PVC for coil forms, and insulators
at HF through VHF frequencies, but I will have to look into the
subject further. Time to break out the network analyzer, etc...

Thanks for the info.

-Chuck Harris


John Lyles wrote:

For a comparison of PVC versus PE (HDPE is just as good), the best source of
dielectric loss mesurements is Von Hipples work from MIT, around WWII. Since you may
not have his text book, can download the data from "Tables of Dielectric Materials"
from DTIC.MIL, I think that's the Defense Technical Info Center. Google it, and Von
Hipples name. Once you downloaded the PDF, look at page 116 for polyvinyl Chloride
and page 153 for polyethylene. Dielectric constants for both are relatively similar.
But look at loss tangent. At 1 MHz PVC is 0.016, PE is 0.0002. And you can see
similar difference up to 10^7 (10 MHz) and 10^8 Hz. In RF heating (which is the
effect that loss give), the loss tangent is directly related as is frequency.
Electric field is a squared term. I would not recommend PVC insulation on anything
that has high RF voltage in the MHz, unless you don't mind the loss and the part is
cooled. Using PVC pieces as spiders for an open wire RF transmission line that is
matched is probably OK, but not in a resonant circuit where the electric field rises.
So it depends on the application. PVC is a very polar molecule like water, having a
net dipole moment. These little dipoles are what causes the loss. Don't forget that a
microwave oven at 2450 MHz has a low field strength as it is not a single resonant
mode, in fact the fields are bouncing all around. When I worked for DuPont years ago,
I was in the dielectric heating group. We would get chemists all the time saying
"this stuff is great, I put in in my microwave oven and it only warmed in xx
minutes." To which we would open the cover of our 90 Mhz WT LaRose heater with about
15 kV across the plates, and the PVC would catch on fire in 10-20 seconds. Believe
me, I have done this dozens of times to prove out various hose and insulation
materials in high power RF amplifiers in my workplace.
Re: Repairing flat high voltage ribbon used in HP displays

 

On 2020-12-05 1:34 p.m., Joel Setton wrote:
Hi Toby,

The repair was done more than 30 years ago, and I don't think I remember
all details ! While the epoxy was curing, I think I created pressure on
the flat cable by sticking it tightly between 2 flat and square rubber
blocks (similar to pencil erasers). This ensured that the epoxy layer
was as thin as I could make it, in order to keep the repaired cable thin
and flexible. Fortunately, the delaminated part was not close to the CRT
end of the cable, it was closer to the connector block. But I definitely
remember taking the CRT out of the 181A, because there was no way I
could do a proper repair job if the CRT stayed in the instrument.

If you go the "splicing" way, you may want to check the dielectric
strength of the tubing you'll use. Many heatshrink tubes are rated for
1000 or 1500V, and we're talking several kilovolts on the CRT. Just to
That's a good tip, I will need to check. The PDA voltage in the 1331A is
7.5kV.

--Toby


be on the safe side ! You may also look for a tube which is as flexible
as possible, so as to minimize any mechanical strain on the flat cable
after the repair.

Please keep us posted !

Joel
Re: hp 8340B YIG UNLOCK error

 

On Fri, Nov 27, 2020 at 02:23 PM, Raymond Domp Frank wrote:
As said, the stuff quickly dissolved in IPA. No visible traces on the cloth I used. No idea what it was but after removal, the feed-throughs were floating against GND once more. I was quite surprised that the patches had caused not just some leakage at a few 100 kOhms at least but some were below 1kOhm!
I didn't *see* any traces. In a chat with a friend of mine earlier tonight, the thought came up that the problem may have been caused by *silver migration*. Since the bolt/nut and possibly the center conductor may have been made of silver or silver plated, that could well be the problem. Not dissolved in IPA but wiped away! One side of the feed-throughs was inside the die-cast cavities, so not well lit. The visible tarnish may not have been the problem at all!

Raymond

Raymond
Re: Weather resistant, covered Litz wire wanted.

 

This is a copy of a old post (I think mine) from a loop antenna group...

####

For plastics used in RF, you're looking for the compounds with the lowest "loss tangent"/"dissipation factor" (which varies with frequency).

Teflon, polystyrene, polyethylene...

Pretty much anything but PVC!

If you can't buy decent capacitors made with it, it's no good for RF.



See the last column. Compare PTFE to PVC.

has some lovely graphs.

Also, PVC for use in sunlight often has lead in the mix, although they are slowly phasing that out. It's not elemental lead, but still...



####

On 6/12/20 3:15 am, Chuck Harris wrote:
Ordinary PVC is very, very low loss through low microwave frequencies, as is
easily demonstrated by putting a piece in your microwave oven.
Do you have a reference I can look at that shows your assertion?
-Chuck Harris
Andy ZL3AG via groups.io wrote:

Depending on the frequency, PVC's loss tangent will ruin your loop Q, so try to use
HDPE or LDPE instead.

Possible source of litz wire can be transformers used in high efficiency SMPS's, but
the ideal litz wire (wire thickness and qty of wires) changes, even across the MW band.

If you want to build a kick-arse receive loop for MW, I highly recommend the late
Graham Maynard's "Sprial loop with Q multiplier" as found in Practical Wireless - the
best loop I've ever used (feeding into a Racal RA17L).
Re: 8590B power supply repair

 

That is the classic symptom of a shorted bridge rectifier on the
power line input of the supply. Replace the bridge, and the 470uf
cap, and you will be on the road to recovery.

RIFA caps rarely do any more damage than smoke... especially here
in 120V land.

-Chuck Harris

Tom B wrote:

Hello All,

I picked up a clean 8590B SA.? The power supply is bad, HP part number is 0950-1977.?
It acts like a direct short across the AC line (i.e., blows the line fuse
immediately).??? I know about the RIFA cap problem so I will order replacements for
those.? One of the big 470 microfarad electrolytics is bulged a little, but not
leaking.? I will replace both of those.? I also saw a burned resistor.? My question
is; what other parts should I order ahead of attempting the repair?

Tom Bryan

N3AJA
Re: Can capacitors

 

Hi Folks.

CE Dist is in the same building as Antique Electronic Supply in Tempe, AZ. They are just a wholesale arm of the same company.
You can find CE caps at TubesAndMore.com

Dan in Chandler, AZ
Re: 8590B power supply repair

 

Hi Tom,

I am not familiar w/this supply (assume it's NOT from HP) but I would have input diode rectifiers handy (single or bridge) as well as MOSFET's that drive the transformer.
Hope you have a variable AC supply for testing! Good luck.

Mark
Re: Weather resistant, covered Litz wire wanted.

 

For a comparison of PVC versus PE (HDPE is just as good), the best source of dielectric loss mesurements is Von Hipples work from MIT, around WWII. Since you may not have his text book, can download the data from "Tables of Dielectric Materials" from DTIC.MIL, I think that's the Defense Technical Info Center. Google it, and Von Hipples name. Once you downloaded the PDF, look at page 116 for polyvinyl Chloride and page 153 for polyethylene. Dielectric constants for both are relatively similar. But look at loss tangent. At 1 MHz PVC is 0.016, PE is 0.0002. And you can see similar difference up to 10^7 (10 MHz) and 10^8 Hz. In RF heating (which is the effect that loss give), the loss tangent is directly related as is frequency. Electric field is a squared term. I would not recommend PVC insulation on anything that has high RF voltage in the MHz, unless you don't mind the loss and the part is cooled. Using PVC pieces as spiders for an open wire RF transmission line that is matched is probably OK, but not in a resonant circuit where the electric field rises. So it depends on the application. PVC is a very polar molecule like water, having a net dipole moment. These little dipoles are what causes the loss. Don't forget that a microwave oven at 2450 MHz has a low field strength as it is not a single resonant mode, in fact the fields are bouncing all around. When I worked for DuPont years ago, I was in the dielectric heating group. We would get chemists all the time saying "this stuff is great, I put in in my microwave oven and it only warmed in xx minutes." To which we would open the cover of our 90 Mhz WT LaRose heater with about 15 kV across the plates, and the PVC would catch on fire in 10-20 seconds. Believe me, I have done this dozens of times to prove out various hose and insulation materials in high power RF amplifiers in my workplace.
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