Re: When Posting Photos Please include the following...
I prefer to keep the text of discussions and the relevant pictures together, so I create an album on Tekscopes first, then put the pictures in, copy the URL to the album from my browser, and use that URL in my messages.
With respect to the future, I prefer to user the Tekscopes album feature, this way the pictures will be available for all users of Tekscopes since they are already logged in inGroups.io, and if I some day do something stupid with my Goofle account, at least the pictures are safe.. :-)
Leo
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Re: When Posting Photos Please include the following...
I'm lazy and most times can't be bothered to log into groups.io, let alone search for some photo. Unless you provide a freely available direct link I probably won't look at it. I realize that is no great loss to anyone, but just wanted to point out if you want your photos seen a direct link (ideally with no login) is in your own interest. There are many free services that host photos and let you share them via a URL, such as google photos. Tinypic also worked great but now they have annoying ads. For archival purposes the group photo space might be ideal, but for accessibility it's almost as bad as Yahoo was. ST On Thu, Jul 26, 2018 at 4:08 PM, Dennis Tillman W7PF <dennis@...> wrote: Just a reminder:
If you announce to TekScopes members that you posted photo(s) to a TekScopes
photo album please include a link to their exact location, the title of the
photo album, and if it was created some time prior to your post date, the
creation date of the album.
If you take a moment to these three things in your announcement it will save
everyone interested in looking at your photos the time it takes to hunt
through the photo albums.
Yes, I know you can order the albums by date created or by title. Don't
assume your photo album will be looked at immediately in which case it can
be quickly found by creation date. Consider the case where someone reads
your post years later and wants to see the photos.
Dennis Tillman W7PF
--
Dennis Tillman W7PF
TekScopes Moderator
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Hi all, Bruce, thanks for your addition, for now I only can test "dry", so without the PS actually working, because the FET's and diode's are not here yet. But I did some measurements on the driver signal driving the gate of the FET (without a FET installed) The switcher in my scope does free run at 66,5kHz / 15usec, and delivers zero-going OFF-pulses with a 2usec width. Rise and fall times are about 100nsec each. I measured the same signals, but now with a 1nF capacitor installed at the G-S pins. Basically, what I see is that there is no difference in the rise-and-fall times, only the high level (in between the low 2usec pulses) becomes a bit dirty. But since the FET is switching ON around 3,5V - 4V, the part of the signal that becomes dirty is way beyond the point where the FET switches "ON", so that should not be a problem. So, my (probably) premature conclusion is: the FET I ordered should work fine. It's capacity does not have any effect on the rise-and-fall times, it's own turn-on time is way smaller than the applied pulse, and the ON-resistance is lower, so dissipation should be lower. But, we all know Mr. Murphy (only few people know he actually was an optimist) so -as always- the proof of the pudding will be in the eating.... I took some pictures of the signals and I put them in the album again: /g/TekScopes/album?id=64919&p=pcreated,,,20,1,0,0 To be continued, Un saludo, Leo
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When Posting Photos Please include the following...
Just a reminder:
If you announce to TekScopes members that you posted photo(s) to a TekScopes
photo album please include a link to their exact location, the title of the
photo album, and if it was created some time prior to your post date, the
creation date of the album.
If you take a moment to these three things in your announcement it will save
everyone interested in looking at your photos the time it takes to hunt
through the photo albums.
Yes, I know you can order the albums by date created or by title. Don't
assume your photo album will be looked at immediately in which case it can
be quickly found by creation date. Consider the case where someone reads
your post years later and wants to see the photos.
Dennis Tillman W7PF
--
Dennis Tillman W7PF
TekScopes Moderator
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Re: Replacing Electrolytics in a 465/465B
Hi Victor,
I'm asking $8 each (shipping included) for one board for U.S. destinations. Since shipping would be calculated separately for overseas, the boards would be $5 each. Do you have a shipping carrier preference? Looking at USPS, the prices are rather high to France but I ma be looking at the wrong options.
Thanks,
Barry - N4BUQ
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----- Original Message ----- From: "Victor via Groups.Io" <vmcfer@...>
To: [email protected]
Sent: Thursday, July 26, 2018 2:52:17 AM
Subject: Re: [TekScopes] Replacing Electrolytics in a 465/465B
Hello Barry,
Nice job and clean solution congrats. I have 2 x 465B and one 465 that need
to be recap soon. I would love to get 3 boards. What is the price for them.
Also I live in France did you accept international shipping? Also the
related cost.
Please let me know.
Have a nice day.
Victor
-----Original Message-----
From: n4buq <n4buq@...>
To: TekScopes <[email protected]>
Sent: Wed, Jul 25, 2018 1:05 am
Subject: [TekScopes] Replacing Electrolytics in a 465/465B
Recently, I had a problem with the LV supplies in my 465B. Thinking it was a
shorted electrolytic can, I decided to replace all of them (although it
turned out to be a shorted tantalum but had already pulled the cans before
finding the real problem).
I decided to design a small PC board on which to mount modern snap-in caps.
THe board mounts with standoffs in the exising larger holes that are left
when the cans are removed and allow replacement of the snap-ins if/when they
fail and that can be done without further soldering on the original board.
Pictures of the board and the process are in the following album:
/g/TekScopes/album?id=64929
If anyone is interested, I have extra boards for sale.
Thanks,
Barry - N4BUQ
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Re: All TekScopes email sent to Spam
Hi Chuck,
A common misconception is that an email Sender whose IP address is listed on a DNSBL (Domain Name System-based Blackhole List) is 'blocked' from sending out email. In fact Senders are in no way prevented by DNSBLs from sending email. The Spamhaus DNSBLs are used only by RECEIVING mail systems on private networks and are used voluntarily.
Spamhaus does not tell a 3rd-party mail system what to do with an item of email, the 3rd-party mail system asks Spamhaus for an opinion and Spamhaus responds to that request with its opinion. In effect the receiving mail server asks the Spamhaus DNSBL "Does this Sender's IP Address exist on the Spamhaus database?", the Spamhaus DNSBL simply responds with a "Yes" if present or, if not present does not respond at all (no response means "we have no opinion on that IP Address").
Dennis Tillman W7PF
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-----Original Message-----
From: Chuck Harris
Sent: Thursday, July 26, 2018 5:33 AM <snip>
A long while ago, I engaged in an email conversation with a group member
that did not like what I had to say, and rather than talk to me about
it, he reported my email address to the misguided SJW folks at spamhaus.
From that point on, my email was rejected by every ISP that used their
lists of "known" spammers to "protect" their customers. Verizon FIOS
accounts were, at that time, using yahoo as their email system, and they
were one of the ISPs that were using the spamhaus lists.
-- Dennis Tillman W7PF TekScopes Moderator
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Re: All TekScopes email sent to Spam
A long while ago, I engaged in an email conversation with
a group member that did not like what I had to say, and rather
than talk to me about it, he reported my email address to
the misguided SJW folks at spamhaus. From that point on,
my email was rejected by every ISP that used their lists of
"known" spammers to "protect" their customers. Verizon FIOS
accounts were, at that time, using yahoo as their email system,
and they were one of the ISPs that were using the spamhaus lists.
Verizon has subsequently dropped yahoo to avoid an antitrust
violation punishment.
To get off of the list would have required me to send spamhaus
all of my private information, which I thought was an excessive
requirement under the circumstances, so I let it be. I had other
email accounts.
When you use yahoo's email services, you are given the option
during setup of deciding whether you want your spam protection
to be none, moderate, or full. It defaults to full. You can
change that setting at any time by logging into your yahoo account
and adjusting your preferences.
Given that groups.io has siphoned off great quantities of yahoo's
groups, it would not surprise me at all to find out that yahoo has
retaliated by banning groups.io to the spam lists.
-Chuck Harris
machineguy59 via Groups.Io wrote:
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I thought our group was using "groups.io" not Yahoo. Yahoo should not be involved unless they are your email client. I use Yahoo email client and web based email. That Yahoo client dumped all of my messages to SPAM one day last week. But I marked them as "Not Spam" and everything has be good since then.
On ?Wednesday?, ?July? ?25?, ?2018? ?03?:?18?:?04? ?PM? ?CDT, John Griessen <john@...> wrote:
On 07/25/2018 02:36 PM, Harvey White wrote:
It's possible
that the classification of the yahoo email has changed somehow,
causing your email program to put it elsewhere. Right. various yahoo.com servers may have been downgraded in their trustworthiness
and then the settings of your junk sensing flag it as junk. If you change settings to
allow from yahoo it will probably come through. That's called whitelisting.
No problem here using thunderbird email reader.
I also run my own mail server and it is not using the real time blacklisting
rankings of yahoo to reject mail from yahoo. Yahoo is still deemed trustworthy by them
as far as I can tell.
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Re: Looking for Power Cord for 400-series Scope
The manual I have shows a Belden number. I looked for that as well but no luck.
Thanks,
Barry - N4BUQ
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----- Original Message ----- From: "Michael A. Terrell" <mike.terrell@...>
To: [email protected]
Sent: Wednesday, July 25, 2018 11:12:38 PM
Subject: Re: [TekScopes] Looking for Power Cord for 400-series Scope
Wasn't Tek using Belden power cords at that time?
Michael A. Terrell
-----Original Message-----
From: Phillip Potter <p.potter@...>
Sent: Jul 25, 2018 11:56 PM
To: [email protected]
Subject: Re: [TekScopes] Looking for Power Cord for 400-series Scope
I wish to add my two cents...
I purchased some power cord to replace the butched one on my 453 (w/
same wire specs) only to find that it was too big (overall size) to fit
the cable clamp on the scope! I was forced to whittle the outside sheath
down to get it to fit... I was not happy but did end up with a cord that
included a plug with a cord holder.? I learned my lesson; never
assume... I know, I know!
Phil
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Dont forget the gate drain capacitance, whilst it may be smaller than the gate source capacitance the voltage swing across it can be large. The miller effect due to Cgd can usually be easily seen in the switching characteristics.
Bruce
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On 26 July 2018 at 20:20 satbeginner <castellcorunas@...> wrote:
Hi all,
with respect to FET's, I'd like to think of them as purely "Voltage" driven.
So, imho you're both making the same point:
If an one fet has a bigger input capacitance than the other, the drive circuit needs to be able to reach the required ON-voltage by delivering a higher current to charge the higher input capacitance of that FET.
If a FET need a higher input charge (nC) to switch on, that may be just the combination of ON-voltage and Input capacitance of that particular FET.
Basically: Q = C x V , Charge (Coulombs) = Capacitance (F) x Voltage (V)
The FET i ordered (IPA60R280E6) has a GS threshold voltage of 3-3,5V, so the 14V puse should be high enough to drive it, Voltage wise.
The original FET IRF710 has a GS threshold voltage of 4V.
I like the idea of running the chip by applying a test voltage of 28V down to 14V as used to test the chip as described in H?kan's document, and, while running, put a 1nF capacitor (imitating a worst case FET) in place of the real FET's G-S.
This way, using a second scope, I can see if the driver circuit is capable of driver this higher, capacitive load.
All this with Q9030 removed of course.
If not, I even may change (lower) R909 a bit.
A combination of R909 at 39Ohm and 200pF (original FET) would give an approximate risetime of 8ns;
A combination of R909 at 39Ohm and 1000pF (replacement FET) would give an approximate risetime of 40ns.
For now I ignore the ristime of Q908, the drive transistor in this comparison.
I will try the capacitor test later this afternoon.
Assume the switching frequency of the PS is 40kHz, thus having a period of 25us, so even with a dutycycle of 10% ON-pulses (ON-time 2,5us) the new risetime should work OK in terms of pulse duration.
The thing that might be a thingy could be the power consumption of the FET during the ON-OFF transitions, and for that reason it can be helped to increase the risetime by reducing R909 to force the FET to switch fully ON faster.
On the other hand, having a way lower ON-resistance could make up for the power consumption durig transistions
So far my thoughts, any ideas?
Un saludo,
Leo
|
Hi all,
with respect to FET's, I'd like to think of them as purely "Voltage" driven.
So, imho you're both making the same point:
If an one fet has a bigger input capacitance than the other, the drive circuit needs to be able to reach the required ON-voltage by delivering a higher current to charge the higher input capacitance of that FET.
If a FET need a higher input charge (nC) to switch on, that may be just the combination of ON-voltage and Input capacitance of that particular FET.
Basically: Q = C x V , Charge (Coulombs) = Capacitance (F) x Voltage (V)
The FET i ordered (IPA60R280E6) has a GS threshold voltage of 3-3,5V, so the 14V puse should be high enough to drive it, Voltage wise.
The original FET IRF710 has a GS threshold voltage of 4V.
I like the idea of running the chip by applying a test voltage of 28V down to 14V as used to test the chip as described in H?kan's document, and, while running, put a 1nF capacitor (imitating a worst case FET) in place of the real FET's G-S.
This way, using a second scope, I can see if the driver circuit is capable of driver this higher, capacitive load.
All this with Q9030 removed of course.
If not, I even may change (lower) R909 a bit.
A combination of R909 at 39Ohm and 200pF (original FET) would give an approximate risetime of 8ns;
A combination of R909 at 39Ohm and 1000pF (replacement FET) would give an approximate risetime of 40ns.
For now I ignore the ristime of Q908, the drive transistor in this comparison.
I will try the capacitor test later this afternoon.
Assume the switching frequency of the PS is 40kHz, thus having a period of 25us, so even with a dutycycle of 10% ON-pulses (ON-time 2,5us) the new risetime should work OK in terms of pulse duration.
The thing that might be a thingy could be the power consumption of the FET during the ON-OFF transitions, and for that reason it can be helped to increase the risetime by reducing R909 to force the FET to switch fully ON faster.
On the other hand, having a way lower ON-resistance could make up for the power consumption durig transistions
So far my thoughts, any ideas?
Un saludo,
Leo
|
Re: Replacing Electrolytics in a 465/465B
Hello Barry,
Nice job and clean solution congrats. I have 2 x 465B and one 465 that need to be recap soon. I would love to get 3 boards. What is the price for them. Also I live in France did you accept international shipping? Also the related cost.
Please let me know.
Have a nice day.
Victor
toggle quoted message
Show quoted text
-----Original Message----- From: n4buq <n4buq@...> To: TekScopes < [email protected]> Sent: Wed, Jul 25, 2018 1:05 am Subject: [TekScopes] Replacing Electrolytics in a 465/465B Recently, I had a problem with the LV supplies in my 465B. Thinking it was a shorted electrolytic can, I decided to replace all of them (although it turned out to be a shorted tantalum but had already pulled the cans before finding the real problem). I decided to design a small PC board on which to mount modern snap-in caps. THe board mounts with standoffs in the exising larger holes that are left when the cans are removed and allow replacement of the snap-ins if/when they fail and that can be done without further soldering on the original board. Pictures of the board and the process are in the following album: /g/TekScopes/album?id=64929If anyone is interested, I have extra boards for sale. Thanks, Barry - N4BUQ
|
Re: All TekScopes email sent to Spam
If you're using Yahoo mail to read messages, it's happening because you've hit the Spam button instead of Delete.? The button locations move, and it's easy to hit the spam button if you're not careful.? I do it about once every other week with some of my email.? Three times I've received a nastygram stating that I've been terminated from IO because of this, but there is always a link to rejoin the group in question if it was an error.? That's always worked, so far. -Dave From: Andre de guerin via Groups.Io <testing_h@...> To: [email protected] Sent: Wednesday, July 25, 2018 12:25 PM Subject: Re: [TekScopes] All TekScopes email sent to Spam Same here. Any ideas? www.cwgsy.net/private/mandoline "Error 008472. Horrible bug encountered. $Deity knows what happened." ? ? On Wednesday, 25 July 2018, 19:36:02 GMT+1, Carl Hallberg via Groups.Io <n9ess@...> wrote: Help, Now all my TekScopes email is sent to spam folder.? Is this a Yahoo problem?? Carl Hallberg? (W9CJH)
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Just wanted to get a little clarity here and also do an update. Went through a number of the scopes I have now and have found three of them where the wet tant has already been replaced with aluminum electrolytics same one that is leaking on the 466 board I am working on. On one of them it was replaced with a 1000uf 10v and on another a 1000uf 35v was used they replaced a 1000uf 10v wet tant they are both larger but fit in place. There is no way to fit a three times capacitance increase in place for that one found a 3300uf 16v that is closest to it at 3 times. There is a very small wet one used on the 464/466 that is 3.6uf 125v that is leaking on the one board I can get a 10uf 160v to replace it think it will fit but would using a solid bulb type of tant same uf but higher voltage be a better choice?
Made a list of wet tants used and what aluminum lytics I could get to replace with and most are close for fitting there are three leakers on this board and one iffy.
Jim
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Re: Looking for Power Cord for 400-series Scope
Wasn't Tek using Belden power cords at that time?
Michael A. Terrell
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-----Original Message----- From: Phillip Potter <p.potter@...>
Sent: Jul 25, 2018 11:56 PM
To: [email protected]
Subject: Re: [TekScopes] Looking for Power Cord for 400-series Scope
I wish to add my two cents...
I purchased some power cord to replace the butched one on my 453 (w/
same wire specs) only to find that it was too big (overall size) to fit
the cable clamp on the scope! I was forced to whittle the outside sheath
down to get it to fit... I was not happy but did end up with a cord that
included a plug with a cord holder.? I learned my lesson; never
assume... I know, I know!
Phil
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Re: Looking for Power Cord for 400-series Scope
I wish to add my two cents...
I purchased some power cord to replace the butched one on my 453 (w/ same wire specs) only to find that it was too big (overall size) to fit the cable clamp on the scope! I was forced to whittle the outside sheath down to get it to fit... I was not happy but did end up with a cord that included a plug with a cord holder.? I learned my lesson; never assume... I know, I know!
Phil
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On 7/25/2018 5:05 PM, n4buq wrote: Okay, Jim. I took a second look and the power entry section is just a small part of the back panel so that would be a fairly easy replacement.
Thanks,
Barry - N4BUQ
----- Original Message -----
From: "Barry" <n4buq@...>
To: [email protected]
Sent: Tuesday, July 24, 2018 11:14:21 PM
Subject: Re: [TekScopes] Looking for Power Cord for 400-series Scope
Okay - I'll take a look again at that. Perhaps it isn't as much trouble as I
was thinking it was.
Thanks,
Barry - N4BUQ
----- Original Message -----
From: "Jim Olson" <v_12eng@...>
To: [email protected]
Sent: Tuesday, July 24, 2018 10:51:07 PM
Subject: Re: [TekScopes] Looking for Power Cord for 400-series Scope
The panel is easy to get off it is held on just two flat head phillips
screws
and the fuse cover box it lifts off with the cord attached you just need to
take off the wires the ground is bolted to the frame right at the cord in
and the white neutral wire is soldered to the fuse box and the power is
attached to a blue piece on the main board soldered too.
Jim
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Did you find a knob for your scope? I have some for different 4** series scopes how is the clear flange marked and does it have a black ring around the cal red knob?
Jim
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Re: WTB: v9.7 EPROMs for 495P memory board
Wow! You da man! Thanks!
RB
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Re: WTB: v9.7 EPROMs for 495P memory board
On Wed, 25 Jul 2018, Rick Boswell wrote: [Edited Message Follows]
Sergey,
Thanks for your detailed post. I am new to SA's in general and to the 495P
specifically but am learning. I have spent considerable time with the
two-volume service manual (700+ pages) as well as reviewing various online
resources such John Miles notes, the KO4BB website, and others. Some
responses & questions re your comments:
Firmware: I am familiar with the physical distribution of the firmware on
the A54 memory board, GPIB board, and front panel. Thanks for your offer
to provide images to allow me to program the EPROMs I am looking for. At
present, I don't have the devices or programmer to do this, and since my
need is almost certain to be a one-time need, I'd like to avoid
programming my own EPROMs if I can purchase what I need. I am also I can program and send you those 2 chips, no problems. Just send me your address off list to ksi at koi8 dot net. No need to pay anything assuming you are in the US so it would make it with domestic First Class package. I have lot of 27256 chips here and it takes just couple of minutes to program 2 chips. --- * * KSI@home KOI8 Net < > The impossible we do immediately. * * Las Vegas NV, USA < > Miracles require 24-hour notice. * *
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Re: WTB: v9.7 EPROMs for 495P memory board
Sergey,
Thanks for your detailed post. I am new to SA's in general and to the 495P specifically but am learning. I have spent considerable time with the two-volume service manual (700+ pages) as well as reviewing various online resources such John Miles notes, the KO4BB website, and others. Some responses & questions re your comments:
Firmware: I am familiar with the physical distribution of the firmware on the A54 memory board, GPIB board, and front panel. Thanks for your offer to provide images to allow me to program the EPROMs I am looking for. At present, I don't have the devices or programmer to do this, and since my need is almost certain to be a one-time need, I'd like to avoid programming my own EPROMs if I can purchase what I need. I am also familiar with the front panel MCU. I own two 495Ps, one of which I purchased in essentially new condition and which works well. Along with this one I received a "parts" 495P which I find works as it should if I simply install a known good A54 memory board which has v9.7 EPROMs installed.. It boots up as a 495P, indicates v9.7 firmware is installed and v1.1 firmware on the front panel processor. So, it would seem that my issues are a result of a defective A54 memory board. I have obtained an A54 memory board from an older 494 unit with v9.0 firmware, and am looking for the v9.7 EPROMs to update this board. I have compared the 494 and 495 memory boards visually and via the parts lists and circuit diagrams in the service manuals and see no meaningful difference. I have moved the v9.7 EPROMs from a good A54 board to the 494 board and installed this in the non-working 495P and it works as expected.
Power supply: As far as I have investigated to date, the power supplies in both 495Ps are working as they should. IOW, I am able to step through the initial checkout section of the service manual and get the results specified in the manual. The capacitors have apparently not yet failed, or may have been replaced by previous owners. Since this has not been an issue yet, I haven't looked carefully to see if these might have been replaced. I see no anomalies in operation which would suggest a power supply problem, but I am still early in the checkout/repair process.
Fan: Not sure yet how to determine if the fan is working properly. For sure, It is turning and moving air. The top of the case gets mildly warm to the touch after several hours of operation, but this doesn't doesn't seem excessive given how much is going on inside this jam packed case. Is there a way to determine if the fan is working as designed? I know it is turning but don't know if it is moving the amount of air it was designed to do. The fan runs quietly, so no apparent mechanical issues.
Thanks,
Rick
K8EZB
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Re: All TekScopes email sent to Spam
Unless they're using a Yahoo email address..
Vince.
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On 07/25/2018 07:35 PM, David C. Partridge wrote: The mail isn't coming from yahoo any more guys, we moved to the groups.io server.
Dave
-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of John Griessen
Sent: 25 July 2018 21:18
To: [email protected]
Subject: Re: [TekScopes] All TekScopes email sent to Spam
On 07/25/2018 02:36 PM, Harvey White wrote:
It's possible
that the classification of the yahoo email has changed somehow,
causing your email program to put it elsewhere. Right. various yahoo.com servers may have been downgraded in their trustworthiness
and then the settings of your junk sensing flag it as junk. If you change settings to
allow from yahoo it will probably come through. That's called whitelisting.
No problem here using thunderbird email reader.
I also run my own mail server and it is not using the real time blacklisting
rankings of yahoo to reject mail from yahoo. Yahoo is still deemed trustworthy by them
as far as I can tell.
--
Michigan VHF Corp.
|
satbeginner
Victor
Michael A. Terrell
Sergey Kubushyn