Keyboard Shortcuts
ctrl + shift + ? :
Show all keyboard shortcuts
ctrl + g :
Navigate to a group
ctrl + shift + f :
Find
ctrl + / :
Quick actions
esc to dismiss
Likes
- TekScopes
- Messages
Search
|
Re: 2440 deal
Bob Albert
Come to think of it, my friend W6TOM in your area has helped me similarly in the past.? Maybe you can connect with him and see if he is planning to go to the hamfest Saturday in Santa Barbara.? If so, he should be willing to bring it down.
toggle quoted message
Show quoted text
Bob818 894-2887 On Tuesday, August 6, 2019, 06:35:55 PM PDT, Robert Simpson via Groups.Io <go_boating_fast@...> wrote:
If I shipped it, I double box ( as those who bought o_scope CRTs know). so at 30 Lbs (item plus packing) boxed dimension 24x18x12. The USPS calculator ground delivery shows $80 from 95630 to Bangor Maine (worst case) Cheaper of course to LA or other (LA would be $45). Bob |
|
Re: 2440 deal
Bob Albert
Well I was hoping to meet and pick it up but that doesn't appear to be an option.? So my investment jumps to $95.? I probably shouldn't do it.
toggle quoted message
Show quoted text
Bob On Tuesday, August 6, 2019, 06:35:55 PM PDT, Robert Simpson via Groups.Io <go_boating_fast@...> wrote:
If I shipped it, I double box ( as those who bought o_scope CRTs know). so at 30 Lbs (item plus packing) boxed dimension 24x18x12. The USPS calculator ground delivery shows $80 from 95630 to Bangor Maine (worst case) Cheaper of course to LA or other (LA would be $45). Bob |
|
Re: Simulator
This is a part of an off line discussion.? JR has a 465B with the trace off to the right.? From what I can tell, the CRT is ok, and most of the horizontal amp except for the differential stage is more or less (pot adjustable) in balance.
toggle quoted message
Show quoted text
JR simulated the circuit with one simulator, I simulated the first stages with another.? His simulation doesn't seem to agree with reality (let alone the schematic voltages).? Mine (Multisim Blue, since discontinued) agrees with the schematic, but not reality as measured.? We're trying to get the first stage (differential, emitter coupled) to balance.? Having replaced most of the transistors, it's not happening, so he's doing the measuring, and I'm doing the "try to figure out what's going on" part. Harvey. Feel free to reply and comment off list. On 8/6/2019 10:07 AM, Tony Fleming wrote:
Can you point me to the place where you talk about it? |
|
Re: 2440 deal
Bob Albert
So buy all three and let us all benefit.? I am willing to pay for gasoline cost to bring it to wherever, such as Santa Barbara.
toggle quoted message
Show quoted text
Bob818 894-2887 after 3PM On Tuesday, August 6, 2019, 05:28:38 PM PDT, Robert Simpson via Groups.Io <go_boating_fast@...> wrote:
OK, I am actually going to ask my daughter who works nearby to try and get one. I actually live in Folsom CA, but she has helped me get stuff before. Bob |
|
Re: O.T. question on MoVs
I am not sure how to test them non-destructively. I only buy parts from
toggle quoted message
Show quoted text
real distributors, so you know what you are getting. Much of the stuff from Amazon / Aliexpess / Ebay, especially from international sources is counterfeit or bad. Markings don't mean anything either as they paint those on fakes too. Regards, Mark On Tue, Aug 6, 2019 at 3:38 PM Ancel <protofabtt@...> wrote:
Hi all, |
|
Re: O.T. question on MoVs
Ancel wrote on 8/6/2019 6:38 PM:
Hi all,Hello, Ancel-- Since there are no markings --including (I assume) any safety agency markings, I'd be strongly tempted to demand a refund from the seller. You may have received counterfeits or rejects. ?Purchase labeled replacements from an authorized seller to be relatively certain that you're getting reliable and predictable parts. Here's an article describing selection of MOVs: If you're intent on determining what parts you received, you can use a curve tracer to examine the MOV's breakover voltage (the knee of the voltage versus current characteristic) at a specified low current, perhaps 1 mA for smaller sizes). Note that MOVs have a service life because the voltage-clamping mechanism relies on degradation of the oxide layer surrounding the metal granules sintered together. After repeated overvoltages, the granules fuse together and the MOV conducts heavily. MOVs may fail in short-circuit mode. Thus, there should be fuses or circuit breakers between the incoming AC power and the MOVs. To be safe, always buy safety-related and branded components from legitimate sources. 73-- Brad? AA1IP |
|
Re: Tekmate 2402 rebuild and programming
I found it here:
toggle quoted message
Show quoted text
On Tue, Aug 6, 2019 at 11:22 AM A Rhodes <rhodes@...> wrote:
I have uploaded to Github a few different repositories under the user name |
|
O.T. question on MoVs
Hi all,
Somewhat off topic power supply related. I got some MoVs from aliexpress which I ordered to use in series to protect a 277VAC, 90mA mains supply from high transients. They ought to be a pair of 270VAC units in series, shorted across the 2 wire AC supply from high transients. 07D271 type part. They capacitive coupled design (2.2uf, 450VAC polypropylene Caps on both lines) allow for 900VAC transient operation without issue. But ..they shipped unmarked and the supplier is not responding. So it seems I need to do a test bed to validate their function. Any advice on the approach? |
|
Re: General Radio 874 Connector, inner conductor "bendies"
I looked at a couple of 874 s just now. The tips of the small center contacts are pointed and slightly tapered toward the center. The larger of the center contacts are tapered toward the inside and slightly bent outward so that the opposing contacts slide over each other and form a continuous tube. Its somewhat the same as the outside contacts.
toggle quoted message
Show quoted text
While the photo may be an optical illusion it does not look right. I don't think the connector was twisted but someone may have put a 274 banana plug into it and bent it. The 274 _can_ be used on an 874 but one must be careful not to stress it. The design is such that the outer shell makes contact first and pretty much prevents the mating plugs from being twisted. The 874 is a pretty good connector but has the disadvantage of not having a precise reference plane. They can act as a short sliding line. Even when locked the reference plane is uncertain. On 8/6/2019 2:44 PM, Roy Thistle wrote:
Hi All: --
Richard Knoppow dickburk@... WB6KBL |
|
Re: General Radio 874 Connector, inner conductor "bendies"
I don't see any bending. What I see are the sharp edges have been chamfered which makes it easy to mate with another GR874 connector. All my GR874 connectors look the same.
On 2019-Aug-06 5:44 PM, Roy Thistle wrote: Hi All: --- This email has been checked for viruses by AVG. |
|
Re: General Radio 874 Connector, inner conductor "bendies"
Hi Roy
These are hermaphrodite connectors and the picture that you refer to does not appear damaged. 73 George G6HIG On Tuesday, August 6, 2019, 10:44:41 PM GMT+1, Roy Thistle <roy.thistle@...> wrote: Hi All: Apologies, if this has been covered (there are a lot of posts on 874!).. but the picture on Tekwiki of the GR-874 (the one with the plug facing the viewer... so you can see into it)¡ well that picture shows two of the leaves of the center conductor, bent in at the corners, and so having little "bendies" barbs, or tangs. (You have to see the picture!). . My initial question is¡ Is that normal, or is the center conductor of the connector damaged? (You can see a bit of those "bendies" on the leaves of the outer conductor, in the picture, too.) My initial guess is the matching, inserter GR-874, after being rotated, and mated, has damaged the insertee?? If so, how does the mated pair maintain 50 ohms? Best regards and wishes. Roy |
|
General Radio 874 Connector, inner conductor "bendies"
Hi All:
Apologies, if this has been covered (there are a lot of posts on 874!).. but the picture on Tekwiki of the GR-874 (the one with the plug facing the viewer... so you can see into it)¡ well that picture shows two of the leaves of the center conductor, bent in at the corners, and so having little "bendies" barbs, or tangs. (You have to see the picture!). . My initial question is¡ Is that normal, or is the center conductor of the connector damaged? (You can see a bit of those "bendies" on the leaves of the outer conductor, in the picture, too.) My initial guess is the matching, inserter GR-874, after being rotated, and mated, has damaged the insertee? If so, how does the mated pair maintain 50 ohms? Best regards and wishes. Roy |
|
Re: Tekmate 2402 rebuild and programming
I have uploaded to Github a few different repositories under the user name "Tek-User".
You can use google for "github two-user". There are 4 project repositories. One on writing new software for the 2402. Another on repairing an old 2402 and getting it working. And then upgrading the 2402 to a 133MHz 586 EBX motherboard and the complexities that are encountered. Another project ports the new programming from the first project listed here and placing it on an arduino. A tiny arduino can largely replace the entire 2402 as an embedded system with the user interface through the scope. I have found and placed in these repositories various software packages relating to the 2402. One software package I have NOT found is the Tektronix "Program Development Software". This apparently has the source code used for the "dso-sh" and "dos-app" software packages provided by Tektronix. I have searched for the development software by thoroughly googling all variations and themes of this topic and found nothing. Does anyone here have any leads for the Program Development Software? -Tony |
|
Re: Simulator
Can you point me to the place where you talk about it?
toggle quoted message
Show quoted text
Thank you! Tony On Mon, Aug 5, 2019 at 11:19 PM Abc Xyz <yawrdanza@...> wrote:
Harvey, |
Ancel
to navigate to use esc to dismiss