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Re: [TowerTalk] TowerTalk Digest, Vol 203, Issue 3

To: towertalk@contesting.com, towertalk-request@contesting.com
Subject: Re: [TowerTalk] TowerTalk Digest, Vol 203, Issue 3
From: GIL ARROYO <gilcanyon@comcast.net>
Reply-to: GIL ARROYO <gilcanyon@comcast.net>
Date: Sun, 3 Nov 2019 11:48:58 -0800 (PST)
List-post: <mailto:towertalk@contesting.com>
How about a specific recommendation for HF Ferrites?   gil  KI7SJC


> On November 3, 2019 at 9:00 AM towertalk-request@contesting.com wrote:
> 
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> Today's Topics:
> 
>    1. Re: Ferrites 31 vs. 77 material (jimlux)
>    2. Ferrites 31 vs. 77 material (Jim Thomson)
>    3. Re: Ferrites 31 vs. 77 material (jimlux)
>    4. Re: Ferrites 31 vs. 77 material (David Gilbert)
>    5. Re: Ferrites 31 vs. 77 material (Jack Brindle)
>    6. Re: Ferrites 31 vs. 77 material (David Gilbert)
>    7. Re: Ferrites 31 vs. 77 material (Don)
> 
> 
> ----------------------------------------------------------------------
> 
> Message: 1
> Date: Sat, 2 Nov 2019 09:32:13 -0700
> From: jimlux <jimlux@earthlink.net>
> To: towertalk@contesting.com
> Subject: Re: [TowerTalk] Ferrites 31 vs. 77 material
> Message-ID: <a5380ed3-fb89-095a-9b4d-3473784f6f02@earthlink.net>
> Content-Type: text/plain; charset=utf-8; format=flowed
> 
> On 11/2/19 2:28 AM, Jim Brown wrote:
> > On 11/1/2019 6:40 PM, Roger Parsons via TowerTalk wrote:
> >> I would imagine that processing has improved since then, but this must 
> >> still be to some extent true.
> > 
> > You have a vivid imagination. :) I have measured data to prove that. 
> > Also see N6RK's post. As luck would have it, I gave a talk to a Silicon 
> > Valley club tonight on a very different topic, but afterwards fielded 
> > questions about chokes from several engineers who had worked in 
> > manufacturing. When I described my work described in an earlier post 
> > about dealing with component tolerances, they nodded their heads in 
> > agreement.
> > 
> > My first gig after college was at Motorola, which is where I first 
> > learned that a circuit design has to work with every part that gets 
> > plugged in to the circuit board, which means that the design has to work 
> > with components with tolerances that you can and did buy.
> > 
> 
> 
> I haven't checked the catalogs, but I'll bet that the tolerances for 
> parts intended for general purpose choking and transformers are wider 
> than those intended for building inductors.  If a transformer core has a 
> higher mu than expected, it still works just fine as a transformer, 
> barring issues with loss and/or self resonance.  Likewise, for something 
> being used as a lossy choke (as opposed to a resonant choke) you just 
> care that the loss is high enough - if it's twice as high as you 
> expected that's all the better.
> 
> On the other hand, if you're buying inductors for filters or for 
> switching power supplies, the core material has to be pretty consistent.
> 
> Since there *is* some crossover among applications for cores, you could 
> wind up using a poor tolerance core and having it work in a high 
> tolerance application, as a prototype.
> 
> 
> 
> 
> ------------------------------
> 
> Message: 2
> Date: Sat, 2 Nov 2019 10:18:23 -0700
> From: "Jim Thomson" <jim.thom@telus.net>
> To: <towertalk@contesting.com>
> Subject: [TowerTalk] Ferrites 31 vs. 77 material
> Message-ID: <55DEC5CD8B0146FCA2EBBE3276D17FC0@DESKTOPSV54DBH>
> Content-Type: text/plain;     charset="utf-8"
> 
> Date: Sat, 2 Nov 2019 13:25:19 +0000 (UTC)
> From: Roger Parsons <ve3zi@yahoo.com>
> To: "Tower and HF Antenna Construction Topics."
> <towertalk@contesting.com>, "jim@audiosystemsgroup.com"
> <jim@audiosystemsgroup.com>
> Subject: [TowerTalk] Ferrites 31 vs. 77 material
> 
> <Very funny.
> <The posts from both N6RK and AB7E support my statement that variability in 
> ferrite parameters has been known for a very long time. You're the one who 
> asserted that it has just been discovered and that therefore Steve G3TXQ 
> could not have known about it.
> 
> <73 RogerVE3ZI
> 
> ##  I  believe it  was  N3RR  that  bought  700,   (seven  hundred)   type  
> 31  cores  from  one  supplier,  all  from  the  same  lot number..2 years  
> ago.  He  used  a  simple  1 turn  link to test them..and then  graded them.  
> They were all  over the  map,  + and ? 22%.   Thats a whopping  44%   spread. 
>  No  2 ferrites  the  same!     ALL  made  in China......so what do  you 
> expect ?  So  much  for  fairite moving  their  factory  to  China.   QC  
> down  the  tubes  ever  since.    
> 
> Jim   VE7RF
> 
> 
> 
> ------------------------------
> 
> Message: 3
> Date: Sat, 2 Nov 2019 10:51:26 -0700
> From: jimlux <jimlux@earthlink.net>
> To: towertalk@contesting.com
> Subject: Re: [TowerTalk] Ferrites 31 vs. 77 material
> Message-ID: <9213c7ec-2021-0f3e-6424-f68844ac6650@earthlink.net>
> Content-Type: text/plain; charset=utf-8; format=flowed
> 
> On 11/2/19 10:18 AM, Jim Thomson wrote:
> > Date: Sat, 2 Nov 2019 13:25:19 +0000 (UTC)
> > From: Roger Parsons <ve3zi@yahoo.com>
> > To: "Tower and HF Antenna Construction Topics."
> > <towertalk@contesting.com>, "jim@audiosystemsgroup.com"
> > <jim@audiosystemsgroup.com>
> > Subject: [TowerTalk] Ferrites 31 vs. 77 material
> > 
> > <Very funny.
> > <The posts from both N6RK and AB7E support my statement that variability in 
> > ferrite parameters has been known for a very long time. You're the one who 
> > asserted that it has just been discovered and that therefore Steve G3TXQ 
> > could not have known about it.
> > 
> > <73 RogerVE3ZI
> > 
> > ##  I  believe it  was  N3RR  that  bought  700,   (seven  hundred)   type  
> > 31  cores  from  one  supplier,  all  from  the  same  lot number..2 years  
> > ago.  He  used  a  simple  1 turn  link to test them..and then  graded 
> > them.  They were all  over the  map,  + and ? 22%.   Thats a whopping  44%  
> >  spread.  No  2 ferrites  the  same!     ALL  made  in China......so what 
> > do  you expect ?  So  much  for  fairite moving  their  factory  to  China. 
> >   QC  down  the  tubes  ever  since.
> > 
> 
> 
> +/- 20% is a reasonable tolerance for this kind of component -
> 
> from Dexter Epcos:
> "Even with the best grinding methods known today, a certain degree of 
> roughness on ground surfaces cannot be avoided, so that the usual term 
> ?without air gap? or ?ungapped? does not imply no air gap at all. The AL 
> values quoted allow for a certain amount of roughness of the ground 
> faces. The tolerance of the AL value for ungapped cores is ?20 to +30% 
> or ?30 to +40%. Closer tolerances are not available for several reasons. 
> The spread in the AL values of ungapped cores practically equal the 
> spread in ring core permeability (?20% ? ?30%), and the AL value largely 
> depends on the grinding quality of the matching surfaces."
> 
> 
> https://www.ferroxcube.com/en-global/download/download/11
> 
> the "filter" materials (material 3C11, page 77) show mu has a +/- 20% 
> tolerance (yeah, it's for a lower frequency, but I didn't want to go 
> hunting for one for HF...)
> 
> There's also a strong temperature dependence on some of these 
> materials.. mu might go from 1500 at 0C to 2000 at 50C.
> 
> 
> 
> 
> 
> ------------------------------
> 
> Message: 4
> Date: Sat, 2 Nov 2019 11:21:42 -0700
> From: David Gilbert <xdavid@cis-broadband.com>
> To: towertalk@contesting.com
> Subject: Re: [TowerTalk] Ferrites 31 vs. 77 material
> Message-ID: <9b9950d8-42e6-8e8a-4674-8aac1a97cb59@cis-broadband.com>
> Content-Type: text/plain; charset=utf-8; format=flowed
> 
> 
> I find that kind of China bashing pretty funny.? Ridiculous as a 
> generalization.
> 
> I worked for a large semiconductor manufacturer for over thirty years 
> and we ended up putting a joint venture manufacturing operation in China 
> ... not simply for low cost, but also to be able to serve the Asian 
> market better and to be able to head off future tariff concerns within 
> China.? We spec'd our own equipment, we trained all the operators, and 
> we put our own managers in key positions.? Most of those positions are 
> now staffed by locals.? The resulting quality was literally 
> best-in-class on a world basis. MANY other U.S., European, and even 
> Japanese companies have done exactly the same, and nothing says that 
> Fair-Rite hasn't as well.
> 
> It is certainly true that many of the smaller locally owned companies in 
> China have sloppy process and quality control, but companies like the 
> large subcontract outfits in China put equivalent U.S. manufacturing to 
> shame for overall manufacturing excellence.
> 
> In the case of ferrites, the problem is the inherent variability of the 
> process itself and the problem previously existed wherever the ferrites 
> were previously manufactured ... including here in the U.S.? Why you 
> think the variability was less before the manufacturing went to China is 
> beyond me.? Several of us here have already explained that it wasn't.
> 
> Dave?? AB7E
> 
> 
> 
> On 11/2/2019 10:18 AM, Jim Thomson wrote:
> > Date: Sat, 2 Nov 2019 13:25:19 +0000 (UTC)
> > From: Roger Parsons <ve3zi@yahoo.com>
> > To: "Tower and HF Antenna Construction Topics."
> > <towertalk@contesting.com>, "jim@audiosystemsgroup.com"
> > <jim@audiosystemsgroup.com>
> > Subject: [TowerTalk] Ferrites 31 vs. 77 material
> >
> > <Very funny.
> > <The posts from both N6RK and AB7E support my statement that variability in 
> > ferrite parameters has been known for a very long time. You're the one who 
> > asserted that it has just been discovered and that therefore Steve G3TXQ 
> > could not have known about it.
> >
> > <73 RogerVE3ZI
> >
> > ##  I  believe it  was  N3RR  that  bought  700,   (seven  hundred)   type  
> > 31  cores  from  one  supplier,  all  from  the  same  lot number..2 years  
> > ago.  He  used  a  simple  1 turn  link to test them..and then  graded 
> > them.  They were all  over the  map,  + and ? 22%.   Thats a whopping  44%  
> >  spread.  No  2 ferrites  the  same!     ALL  made  in China......so what 
> > do  you expect ?  So  much  for  fairite moving  their  factory  to  China. 
> >   QC  down  the  tubes  ever  since.
> >
> > Jim   VE7RF
> >
> > _______________________________________________
> >
> >
> >
> > _______________________________________________
> > TowerTalk mailing list
> > TowerTalk@contesting.com
> > http://lists.contesting.com/mailman/listinfo/towertalk
> 
> 
> 
> ------------------------------
> 
> Message: 5
> Date: Sat, 2 Nov 2019 13:48:13 -0700
> From: Jack Brindle <jackbrindle@me.com>
> To: David Gilbert <xdavid@cis-broadband.com>
> Cc: towertalk@contesting.com
> Subject: Re: [TowerTalk] Ferrites 31 vs. 77 material
> Message-ID: <A87D4CF5-535F-4325-A270-ECD678646771@me.com>
> Content-Type: text/plain;     charset=utf-8
> 
> Sadly, there is much evidence. Fair-rite quality really took a hit after they 
> moved production to Asia. So much so that many companies have had to 
> institute new QA procedures on incoming product to see if the characteristics 
> come close to fitting the requirements. One of the biggest ones is large 60Hz 
> transformer toroids that were failing in normal service because of the 
> manufacturing issues. The company does still have some non-Asia manufacturing 
> capability, and many companies are specifying product only from those sites.
> 
> So yes, the toroids do have issues that are very problematic.
> 
> Jack, W6FB
> 
> > On Nov 2, 2019, at 11:21 AM, David Gilbert <xdavid@cis-broadband.com> wrote:
> > 
> > 
> > I find that kind of China bashing pretty funny.  Ridiculous as a 
> > generalization.
> > 
> > I worked for a large semiconductor manufacturer for over thirty years and 
> > we ended up putting a joint venture manufacturing operation in China ... 
> > not simply for low cost, but also to be able to serve the Asian market 
> > better and to be able to head off future tariff concerns within China.  We 
> > spec'd our own equipment, we trained all the operators, and we put our own 
> > managers in key positions.  Most of those positions are now staffed by 
> > locals.  The resulting quality was literally best-in-class on a world 
> > basis. MANY other U.S., European, and even Japanese companies have done 
> > exactly the same, and nothing says that Fair-Rite hasn't as well.
> > 
> > It is certainly true that many of the smaller locally owned companies in 
> > China have sloppy process and quality control, but companies like the large 
> > subcontract outfits in China put equivalent U.S. manufacturing to shame for 
> > overall manufacturing excellence.
> > 
> > In the case of ferrites, the problem is the inherent variability of the 
> > process itself and the problem previously existed wherever the ferrites 
> > were previously manufactured ... including here in the U.S.  Why you think 
> > the variability was less before the manufacturing went to China is beyond 
> > me.  Several of us here have already explained that it wasn't.
> > 
> > Dave   AB7E
> > 
> > 
> > 
> > On 11/2/2019 10:18 AM, Jim Thomson wrote:
> >> Date: Sat, 2 Nov 2019 13:25:19 +0000 (UTC)
> >> From: Roger Parsons <ve3zi@yahoo.com>
> >> To: "Tower and HF Antenna Construction Topics."
> >> <towertalk@contesting.com>, "jim@audiosystemsgroup.com"
> >> <jim@audiosystemsgroup.com>
> >> Subject: [TowerTalk] Ferrites 31 vs. 77 material
> >> 
> >> <Very funny.
> >> <The posts from both N6RK and AB7E support my statement that variability 
> >> in ferrite parameters has been known for a very long time. You're the one 
> >> who asserted that it has just been discovered and that therefore Steve 
> >> G3TXQ could not have known about it.
> >> 
> >> <73 RogerVE3ZI
> >> 
> >> ##  I  believe it  was  N3RR  that  bought  700,   (seven  hundred)   type 
> >>  31  cores  from  one  supplier,  all  from  the  same  lot number..2 
> >> years  ago.  He  used  a  simple  1 turn  link to test them..and then  
> >> graded them.  They were all  over the  map,  + and ? 22%.   Thats a 
> >> whopping  44%   spread.  No  2 ferrites  the  same!     ALL  made  in 
> >> China......so what do  you expect ?  So  much  for  fairite moving  their  
> >> factory  to  China.   QC  down  the  tubes  ever  since.
> >> 
> >> Jim   VE7RF
> >> 
> >> _______________________________________________
> >> 
> >> 
> >> 
> >> _______________________________________________
> >> TowerTalk mailing list
> >> TowerTalk@contesting.com
> >> http://lists.contesting.com/mailman/listinfo/towertalk
> > 
> > _______________________________________________
> > 
> > 
> > 
> > _______________________________________________
> > TowerTalk mailing list
> > TowerTalk@contesting.com
> > http://lists.contesting.com/mailman/listinfo/towertalk
> 
> 
> 
> ------------------------------
> 
> Message: 6
> Date: Sat, 2 Nov 2019 16:14:24 -0700
> From: David Gilbert <xdavid@cis-broadband.com>
> To: towertalk@contesting.com
> Subject: Re: [TowerTalk] Ferrites 31 vs. 77 material
> Message-ID: <9f5664d9-22ab-3249-18a9-2632e1827b2c@cis-broadband.com>
> Content-Type: text/plain; charset=utf-8; format=flowed
> 
> 
> 
> Well, if that's the case it means that Fair-Rite did a poor job of 
> transferring the manufacturing, and yes ... I've seen a bunch of other 
> companies do the same crappy job of it especially when all they were 
> looking for was quick cost reduction.? Those companies who made a 
> commitment to do it right have found a large pool of highly 
> conscientious technical labor in China just like we did.? Those who 
> merely tried to port their processes over to some existing facility 
> usually failed.
> 
> My gripe is that simply bashing anything made in China is decades out of 
> date and a bad generalization.
> 
> 73,
> Dave?? AB7E
> 
> 
> On 11/2/2019 1:48 PM, Jack Brindle via TowerTalk wrote:
> > Sadly, there is much evidence. Fair-rite quality really took a hit after 
> > they moved production to Asia. So much so that many companies have had to 
> > institute new QA procedures on incoming product to see if the 
> > characteristics come close to fitting the requirements. One of the biggest 
> > ones is large 60Hz transformer toroids that were failing in normal service 
> > because of the manufacturing issues. The company does still have some 
> > non-Asia manufacturing capability, and many companies are specifying 
> > product only from those sites.
> >
> > So yes, the toroids do have issues that are very problematic.
> >
> > Jack, W6FB
> >
> >> On Nov 2, 2019, at 11:21 AM, David Gilbert <xdavid@cis-broadband.com> 
> >> wrote:
> >>
> >>
> >> I find that kind of China bashing pretty funny.  Ridiculous as a 
> >> generalization.
> >>
> >> I worked for a large semiconductor manufacturer for over thirty years and 
> >> we ended up putting a joint venture manufacturing operation in China ... 
> >> not simply for low cost, but also to be able to serve the Asian market 
> >> better and to be able to head off future tariff concerns within China.  We 
> >> spec'd our own equipment, we trained all the operators, and we put our own 
> >> managers in key positions.  Most of those positions are now staffed by 
> >> locals.  The resulting quality was literally best-in-class on a world 
> >> basis. MANY other U.S., European, and even Japanese companies have done 
> >> exactly the same, and nothing says that Fair-Rite hasn't as well.
> >>
> >> It is certainly true that many of the smaller locally owned companies in 
> >> China have sloppy process and quality control, but companies like the 
> >> large subcontract outfits in China put equivalent U.S. manufacturing to 
> >> shame for overall manufacturing excellence.
> >>
> >> In the case of ferrites, the problem is the inherent variability of the 
> >> process itself and the problem previously existed wherever the ferrites 
> >> were previously manufactured ... including here in the U.S.  Why you think 
> >> the variability was less before the manufacturing went to China is beyond 
> >> me.  Several of us here have already explained that it wasn't.
> >>
> >> Dave   AB7E
> >>
> >>
> >>
> >> On 11/2/2019 10:18 AM, Jim Thomson wrote:
> >>> Date: Sat, 2 Nov 2019 13:25:19 +0000 (UTC)
> >>> From: Roger Parsons <ve3zi@yahoo.com>
> >>> To: "Tower and HF Antenna Construction Topics."
> >>> <towertalk@contesting.com>, "jim@audiosystemsgroup.com"
> >>> <jim@audiosystemsgroup.com>
> >>> Subject: [TowerTalk] Ferrites 31 vs. 77 material
> >>>
> >>> <Very funny.
> >>> <The posts from both N6RK and AB7E support my statement that variability 
> >>> in ferrite parameters has been known for a very long time. You're the one 
> >>> who asserted that it has just been discovered and that therefore Steve 
> >>> G3TXQ could not have known about it.
> >>>
> >>> <73 RogerVE3ZI
> >>>
> >>> ##  I  believe it  was  N3RR  that  bought  700,   (seven  hundred)   
> >>> type  31  cores  from  one  supplier,  all  from  the  same  lot 
> >>> number..2 years  ago.  He  used  a  simple  1 turn  link to test 
> >>> them..and then  graded them.  They were all  over the  map,  + and ? 22%. 
> >>>   Thats a whopping  44%   spread.  No  2 ferrites  the  same!     ALL  
> >>> made  in China......so what do  you expect ?  So  much  for  fairite 
> >>> moving  their  factory  to  China.   QC  down  the  tubes  ever  since.
> >>>
> >>> Jim   VE7RF
> >>>
> >>> _______________________________________________
> >>>
> >>>
> >>>
> >>> _______________________________________________
> >>> TowerTalk mailing list
> >>> TowerTalk@contesting.com
> >>> http://lists.contesting.com/mailman/listinfo/towertalk
> >> _______________________________________________
> >>
> >>
> >>
> >> _______________________________________________
> >> TowerTalk mailing list
> >> TowerTalk@contesting.com
> >> http://lists.contesting.com/mailman/listinfo/towertalk
> > _______________________________________________
> >
> >
> >
> > _______________________________________________
> > TowerTalk mailing list
> > TowerTalk@contesting.com
> > http://lists.contesting.com/mailman/listinfo/towertalk
> 
> 
> 
> ------------------------------
> 
> Message: 7
> Date: Sat, 2 Nov 2019 16:42:28 -0700
> From: Don <w7wll@arrl.net>
> To: towertalk@contesting.com
> Subject: Re: [TowerTalk] Ferrites 31 vs. 77 material
> Message-ID: <d53e8d18-e7dc-423f-a307-ea892bb6da41@arrl.net>
> Content-Type: text/plain; charset=utf-8; format=flowed
> 
> Dave is spot on.
> 
> In a couple of cases I'm familiar with, China not only delivered goods 
> with quality equal to or better than US manufactured items but with 
> their technical capability and desire to excel, were able to offer 
> suggestions that improved the product AND lowered the manufacturing 
> cost. China is not the only example. A significant number of other 
> countries are just as capable as the US to produce high quality goods. 
> Just look at some of the amateur radio 'stuff' available on the market.
> 
> We aren't the only ducks in the pond anymore, and don't blame politics.
> 
> Don W7WLL
> 
> On 11/2/2019 4:14 PM, David Gilbert wrote:
> >
> >
> > Well, if that's the case it means that Fair-Rite did a poor job of 
> > transferring the manufacturing, and yes ... I've seen a bunch of other 
> > companies do the same crappy job of it especially when all they were 
> > looking for was quick cost reduction.? Those companies who made a 
> > commitment to do it right have found a large pool of highly 
> > conscientious technical labor in China just like we did. Those who 
> > merely tried to port their processes over to some existing facility 
> > usually failed.
> >
> > My gripe is that simply bashing anything made in China is decades out 
> > of date and a bad generalization.
> >
> > 73,
> > Dave?? AB7E
> >
> >
> > On 11/2/2019 1:48 PM, Jack Brindle via TowerTalk wrote:
> >> Sadly, there is much evidence. Fair-rite quality really took a hit 
> >> after they moved production to Asia. So much so that many companies 
> >> have had to institute new QA procedures on incoming product to see if 
> >> the characteristics come close to fitting the requirements. One of 
> >> the biggest ones is large 60Hz transformer toroids that were failing 
> >> in normal service because of the manufacturing issues. The company 
> >> does still have some non-Asia manufacturing capability, and many 
> >> companies are specifying product only from those sites.
> >>
> >> So yes, the toroids do have issues that are very problematic.
> >>
> >> Jack, W6FB
> >>
> >>> On Nov 2, 2019, at 11:21 AM, David Gilbert 
> >>> <xdavid@cis-broadband.com> wrote:
> >>>
> >>>
> >>> I find that kind of China bashing pretty funny.? Ridiculous as a 
> >>> generalization.
> >>>
> >>> I worked for a large semiconductor manufacturer for over thirty 
> >>> years and we ended up putting a joint venture manufacturing 
> >>> operation in China ... not simply for low cost, but also to be able 
> >>> to serve the Asian market better and to be able to head off future 
> >>> tariff concerns within China.? We spec'd our own equipment, we 
> >>> trained all the operators, and we put our own managers in key 
> >>> positions.? Most of those positions are now staffed by locals.? The 
> >>> resulting quality was literally best-in-class on a world basis. MANY 
> >>> other U.S., European, and even Japanese companies have done exactly 
> >>> the same, and nothing says that Fair-Rite hasn't as well.
> >>>
> >>> It is certainly true that many of the smaller locally owned 
> >>> companies in China have sloppy process and quality control, but 
> >>> companies like the large subcontract outfits in China put equivalent 
> >>> U.S. manufacturing to shame for overall manufacturing excellence.
> >>>
> >>> In the case of ferrites, the problem is the inherent variability of 
> >>> the process itself and the problem previously existed wherever the 
> >>> ferrites were previously manufactured ... including here in the 
> >>> U.S.? Why you think the variability was less before the 
> >>> manufacturing went to China is beyond me. Several of us here have 
> >>> already explained that it wasn't.
> >>>
> >>> Dave?? AB7E
> >>>
> >>>
> >>>
> >>> On 11/2/2019 10:18 AM, Jim Thomson wrote:
> >>>> Date: Sat, 2 Nov 2019 13:25:19 +0000 (UTC)
> >>>> From: Roger Parsons <ve3zi@yahoo.com>
> >>>> To: "Tower and HF Antenna Construction Topics."
> >>>> <towertalk@contesting.com>, "jim@audiosystemsgroup.com"
> >>>> <jim@audiosystemsgroup.com>
> >>>> Subject: [TowerTalk] Ferrites 31 vs. 77 material
> >>>>
> >>>> <Very funny.
> >>>> <The posts from both N6RK and AB7E support my statement that 
> >>>> variability in ferrite parameters has been known for a very long 
> >>>> time. You're the one who asserted that it has just been discovered 
> >>>> and that therefore Steve G3TXQ could not have known about it.
> >>>>
> >>>> <73 RogerVE3ZI
> >>>>
> >>>> ##? I? believe it? was? N3RR? that? bought? 700,?? (seven 
> >>>> hundred)?? type? 31? cores? from? one? supplier,? all? from the? 
> >>>> same? lot number..2 years? ago.? He? used? a? simple? 1 turn? link 
> >>>> to test them..and then? graded them.? They were all? over the? 
> >>>> map,? + and ? 22%.?? Thats a whopping? 44% spread.? No? 2 ferrites? 
> >>>> the? same!???? ALL? made? in China......so what do? you expect ?? 
> >>>> So? much? for? fairite moving? their? factory? to? China.?? QC? 
> >>>> down? the? tubes ever? since.
> >>>>
> >>>> Jim?? VE7RF
> >>>>
> >>>> _______________________________________________
> >>>>
> >>>>
> >>>>
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> >>>
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> >>
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> >>
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> >
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> >
> >
> >
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> > http://lists.contesting.com/mailman/listinfo/towertalk
> 
> 
> 
> ------------------------------
> 
> Subject: Digest Footer
> 
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> 
> ------------------------------
> 
> End of TowerTalk Digest, Vol 203, Issue 3
> *****************************************
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