开云体育

On 5/11/2024 11:17 PM, Benjamin Badrakh wrote:

So I used cyanocrylateto glue them together. I stopped the fogging effect by putting the knob above a fan to constantly move air. This allows the cyanocrylate vapors to move away from the knob and not precipitate on the knob.
It worked perfectly.

Very clever.

Very cool. How do you reattach the top of the can cleanly? Is there a trick or do you just fill up the empty space with eg. Silicone?

is NOS ok or brand spanking new


On Sun, May 12, 2024 at 9:22?AM n4buq via groups.io <n4buq=
[email protected]> wrote:

Nichicon has discontinued a large part of their leaded capacitors. Their
ULD, UHE, and others, are no longer available in small-value, radial
types. I'm looking for good replacements for blown tantalums for values
under 100uF, etc.

Anyone have suggestions as to what to look for now?

Thanks,
Barry - N4BUQ

Nichicon has discontinued a large part of their leaded capacitors. Their ULD, UHE, and others, are no longer available in small-value, radial types. I'm looking for good replacements for blown tantalums for values under 100uF, etc.

Anyone have suggestions as to what to look for now?

Thanks,
Barry - N4BUQ

Hello everyone,

I've been carrying out expert assessments in the various fields of EMC for 40 years, and in the early years I was able to use a MONROE 175 electrostatic voltmeter to measure how people became charged. In 95 to 98% of cases, they were negatively charged.

But if there's one subject we couldn't care less about, it's whether the discharge is positive or negative. It's only the value of the peak voltage at which the person is charged that counts and has a direct influence on the effect and pain felt. I read at one point that the current value of relative humidity measured was only 20%. With such a low value, it's totally normal to become charged as soon as the person makes the slightest movement.

F1EKU

So I used cyanocrylateto glue them together. I stopped the fogging effect by putting the knob above a fan to constantly move air. This allows the cyanocrylate vapors to move away from the knob and not precipitate on the knob.

It worked perfectly.

Not having a problem at all I'm using comcast e-mail with MS Echo in WIN10. Receive all emails with posts and can answer in the post or as a new message in the web site.

Jim O

A cheap $100 vna can help diagnose signal path issues. This shows what happens when a micro crack in a connector can do.

/g/TekScopes/photo/284401/3583773

Yes, the 2712 is different from the 492 series. But it still has a 1st if via a YIG but now at a slightly higher 2110MHz, 100MHz master and the same 110 2nd if etc. It is a completely new physical design, newer CPU, maybe about 2-3 times faster (my estimate) than the 68xx in the 492. But, the general RF design is similary, phase gate, inner, outer loop control, analog log amps, 2 frequency markers and all that.

The relay atten is a much less expensive design than the uwave cavity in the 492's which works up to10 times the frequency using thin film wafers. (The 492 attens are not repairable but can be found on paybay).

As a side note, the 275x 279x series parts are way way more expensive than 492 parts (ignoring the 40GHz model) I wonder what 2712 parts costs are like?

Need a new-ish computer?

discountelectronics.com -- I have half a dozen from them. Year warranty on
most. Take a look. My only financial interest is the money I save on not
buying new computers at retail.

73
Jim N6OTQ

Funny how upgrade usually means downgrade and yes my system does not flow as well as it did.
This page came up at the top where I could not see a place to respond.
Going back from a message on the bottom winds up at the top instead of where I was, what next?
--
Jeffeelcr

Hi Jon,

The 2712 has been in dedicated power supply ripple QC duty. It is fed by a jig with 0.1 uF caps blocking the 14 V supply DC, so it only sees any RF on the SMPS supply rails. It is possible that one of the supplies being checked had a bad output filter and very high ripple, but I do not remember one.

Well, if that first mixer is burnt out I wonder if the CR256B or CA130 diodes have failed? I did a search through the archive for 2712 issues and did not find any other reports where the fault was found. I guess I'll have to pull the can and do some measuring.

Cheers!
Howie

I have never paid that much for a computer. You can buy a new computer, but
I typically buy recent, used business computers for under$100 and get
several years of life out of them.
I prefer a used business grade, to a new, consumer grade system which isn't
likely to survive as long as its installed OS. Keep the old computer, with
the old software if it will still do the job.
I have working computers back to Win 95. and several older Commodore
computers to run old software, or to convert files

On Sat, May 11, 2024 at 2:28?PM Greg Muir via groups.io <big_sky_explorer=
[email protected]> wrote:

I use an old XP machine for email so as not to clutter up my main
machine. But now I can no longer send replies via the groups.io page.
When sending the message it no longer goes through and I only receive a
“{"DraftID":26752611}” reply. But replying through the digest I receive
via my email (use Yahoo for these types of sites) sending messages is
successful.

Somewhat unrelated to this there is the “Your Browser is No Longer
Supported” that occasionally pops up when bringing up a webpage. This XP
computer is using the last version of the FireFox browser that can be used
under this system. The computer has some issues trying to support other
later browser variants. So one has to look at an upgrade to a later OS.
But this computer also has a multitude of older software that will not work
with later operating systems unless upgraded.

Solution?

1. Buy new computer with recent operating system: ~$1000.00
2. Purchase new software to work on new operating system: ~$2800.00

Nearly 4 thousand dollars expenditure just to look at a single website? I
think not.

Problem here is that the people who design websites simply let those who
have older systems fall through the cracks. The young puppy programmers
are not willing to learn legacy systems. That serves as a good reflection
on how companies nowadays distribute their respect for customers. Not
everybody is on the bleeding edge of technology for many reasons.

It’s interesting to note that some actual vary good and professional
organizations have coded their websites to honor older browsers when they
send out probes to see what the client has. These are people who really
care for their website visitors. I have also experienced some companies
who will offer a XP patch for their upgraded software if requested.

Fundamentally things are working well with this older machine except for
the occasional “surprises” like the one that has now occurred with
groups.io.

I realize that there are many people out there who enjoy a brisk encounter
doing “scientific experiments” to accommodate website changes but I simply
don’t have the luxury of a lot of time to do so. When something works well
I simply stick with it. And I’m not about to jump through a dozen hoops
just to satisfy a variant introduced by just one website. I do understand
the aspects of technical progress but it has been my impression to have
companies concentrate on “neat, new & nifty” advances purely for
profit/stockholder motives is one of the issues doing damage to many people
out there from a user and cost standpoint.

Greg

Howard, was the input ever overloaded, the mixer is easy to burn out, and the symptoms are low sensitivity eg -24 db down.

Did the issue develop after measurement of a TX , PA or generator capability over 10 DVM?

Jon

Hi Jaap,
I'm back on the 2712 diagnosis...

I tested all the relays in the RF Attenuator block...and they were good, but upon reassembly the issue still exists: it does indeed show input, but the level is some 24 dB down, frequency dependent. I had thought the Calibrator signal was proper, but the unit fails just about all the Amplitude Normalizations, so the problem likely exists with the calibration signal as well. Since the RF Attenuator relays are OK, the issue must be afterwards, in the 1st Converter, LO or some other block I do not have test equipment to check, I only have a 350 MHz scope...

Barring any further ideas from the group, is there anyone in the US Southeast who repairs these older Tek gear?

Thanks for the help,
Howard Hoyt

?ann lau., 11. maí 2024 kl. 13:26 skrifa?i david via groups.io <davide_us=
[email protected]>:

Now that I think about removing the front panel, it comes off without
removing the knobs. I had to remove the knobs to replace the BNC connector.
Are the relay contacts hard to get at in the attenuator? I don't want to
damage the attenuator.

Once you get the attenuator out, it’s easy to get into it. You do need to
desolder the connection to the preeamp, though. Be careful with the lion
foot contacts, though.

Stand Down. I found enough to proceed.

I use an old XP machine for email so as not to clutter up my main machine. But now I can no longer send replies via the groups.io page. When sending the message it no longer goes through and I only receive a “{"DraftID":26752611}” reply. But replying through the digest I receive via my email (use Yahoo for these types of sites) sending messages is successful.

Somewhat unrelated to this there is the “Your Browser is No Longer Supported” that occasionally pops up when bringing up a webpage. This XP computer is using the last version of the FireFox browser that can be used under this system. The computer has some issues trying to support other later browser variants. So one has to look at an upgrade to a later OS. But this computer also has a multitude of older software that will not work with later operating systems unless upgraded.

Solution?

1. Buy new computer with recent operating system: ~$1000.00
2. Purchase new software to work on new operating system: ~$2800.00

Nearly 4 thousand dollars expenditure just to look at a single website? I think not.

Problem here is that the people who design websites simply let those who have older systems fall through the cracks. The young puppy programmers are not willing to learn legacy systems. That serves as a good reflection on how companies nowadays distribute their respect for customers. Not everybody is on the bleeding edge of technology for many reasons.

It’s interesting to note that some actual vary good and professional organizations have coded their websites to honor older browsers when they send out probes to see what the client has. These are people who really care for their website visitors. I have also experienced some companies who will offer a XP patch for their upgraded software if requested.

Fundamentally things are working well with this older machine except for the occasional “surprises” like the one that has now occurred with groups.io.

I realize that there are many people out there who enjoy a brisk encounter doing “scientific experiments” to accommodate website changes but I simply don’t have the luxury of a lot of time to do so. When something works well I simply stick with it. And I’m not about to jump through a dozen hoops just to satisfy a variant introduced by just one website. I do understand the aspects of technical progress but it has been my impression to have companies concentrate on “neat, new & nifty” advances purely for profit/stockholder motives is one of the issues doing damage to many people out there from a user and cost standpoint.

Greg

Now that I think about removing the front panel, it comes off without removing the knobs. I had to remove the knobs to replace the BNC connector. Are the relay contacts hard to get at in the attenuator? I don't want to damage the attenuator.
David

So, the relay contacts are in the attenuator? I really don't want to remove the front panel if I can avoid it. Knobs are prone to breakage when removing them. But at least I'm sure that the relay contacts are the problem. If it continues to be an issue, I will have to open it up. I'm wondering if warming the knobs with a heat gun will allow me to remove them without breaking them. When I had to replace a BNC connector on my first 2465, I broke one Knob during removal. Previous owners probably never used 50ohm DC input enough to keep relay contacts clean.
David