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Re: Recreating an old board for the 7854
Time for the Cone of Silence before we get the OT warning!
Now back to the 7854. I use the board to run my analog backup 7854 parts. It has no Max, I mean smarts, in it. I kludged in 7k readout board and now I have a fully functional 7804. Some of the boards are early prototype boards and some from different production runs. Think of Johnny Cash¡¯s ¡°One Piece At A Time.¡± No fins on it though! |
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Re: Recreating an old board for the 7854
Looks like a suitable new chip would be this
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Vce - 25Vdc Hfe 120-240 Frequency - 800 Mhz -----Original Message-----
From: [email protected] <[email protected]> On Behalf Of Glenn Little Sent: Tuesday, July 20, 2021 4:05 PM To: [email protected] Subject: Re: [TekScopes] Recreating an old board for the 7854 A web search shows Frequency as 500 MHz as guaranteed minimum. Glenn On 7/20/2021 3:49 PM, Zentronics42@... wrote: Thanks for all the help.-- ----------------------------------------------------------------------- Glenn Little ARRL Technical Specialist QCWA LM 28417 Amateur Callsign: WB4UIV wb4uiv@... AMSAT LM 2178 QTH: Goose Creek, SC USA (EM92xx) USSVI, FRA, NRA-LM ARRL TAPR "It is not the class of license that the Amateur holds but the class of the Amateur that holds the license" |
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Re: Recreating an old board for the 7854
That was the number I was unable to find. I had a feeling these needed to be fast as they are in the trigger circuit and the 7854 is a 400 Mhz frame. Test triggering to 500 Mhz is what I was expecting maybe even higher. Good news is as this is a from scratch board design package does not matter as I will be ordering parts. So for this spot I need lowish Vce and fast.
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Ill keep working on the boards. When the design is checked and tested If there is any interest in these let me know. Not sure how many out there want to tackle a full cal of a 7854. Zen -----Original Message-----
From: [email protected] <[email protected]> On Behalf Of Glenn Little Sent: Tuesday, July 20, 2021 4:05 PM To: [email protected] Subject: Re: [TekScopes] Recreating an old board for the 7854 A web search shows Frequency as 500 MHz as guaranteed minimum. Glenn On 7/20/2021 3:49 PM, Zentronics42@... wrote: Thanks for all the help.-- ----------------------------------------------------------------------- Glenn Little ARRL Technical Specialist QCWA LM 28417 Amateur Callsign: WB4UIV wb4uiv@... AMSAT LM 2178 QTH: Goose Creek, SC USA (EM92xx) USSVI, FRA, NRA-LM ARRL TAPR "It is not the class of license that the Amateur holds but the class of the Amateur that holds the license" |
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Re: Recreating an old board for the 7854
A web search shows Frequency as 500 MHz as guaranteed minimum.
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Glenn On 7/20/2021 3:49 PM, Zentronics42@... wrote:
Thanks for all the help. --
----------------------------------------------------------------------- Glenn Little ARRL Technical Specialist QCWA LM 28417 Amateur Callsign: WB4UIV wb4uiv@... AMSAT LM 2178 QTH: Goose Creek, SC USA (EM92xx) USSVI, FRA, NRA-LM ARRL TAPR "It is not the class of license that the Amateur holds but the class of the Amateur that holds the license" |
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Re: Recreating an old board for the 7854
Well, actress Barbara Feldon is still alive? evidently.? ?She's 88, though, so not nearly as hot as she was in Get Smart.? ? ? ?Jim?Sent from my Verizon, Samsung Galaxy smartphone
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-------- Original message --------From: Clark Foley <clarkfoley@...> Date: 7/20/21 12:49 PM (GMT-08:00) To: [email protected] Subject: Re: [TekScopes] Recreating an old board for the 7854 Where is Agent 99 when you need her!
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Re: Recreating an old board for the 7854
You guys aren't as Smart as you think you are!? ? ? ? ? ? Jim Ford?Sent from my Verizon, Samsung Galaxy smartphone
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-------- Original message --------From: Tom Lee <tomlee@...> Date: 7/20/21 12:17 PM (GMT-08:00) To: [email protected] Subject: Re: [TekScopes] Recreating an old board for the 7854 Missed it by that much.Sent from my iThing, so please forgive typos and brevity.> On Jul 20, 2021, at 12:13 PM, Clark Foley <clarkfoley@...> wrote:> > ?Would you believe octal latches? Sorry about that, Chief.> > > > >
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Re: Recreating an old board for the 7854
Thanks for all the help.
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I have about 80% finished with the schematic. I need to find a replacement for the 2N5769 The documentation says this was a "Switching Transistor" but it does not say the switching frequency. But that is the next hurdle that needs to be cleared. I will post the schematic and the board layout when it is finished to make sure I did not make any errors. Also need to get the pin outs for P190. At the moment P190 looks like it is the board edge connector. All advise is welcome and thanks in advance. -----Original Message-----
From: [email protected] <[email protected]> On Behalf Of Raymond Domp Frank Sent: Tuesday, July 20, 2021 3:28 PM To: [email protected] Subject: Re: [TekScopes] Recreating an old board for the 7854 On Tue, Jul 20, 2021 at 09:12 PM, Clark Foley wrote: Since we're at it: It's not 8 latches: There are 8 D-type flip-flops in a '374. Latches pass the input with one control level (the output follows the input, no clock involved) and latch their input value with the control at the other level, much like an analog sample and hold. Compare 7475 (quad latch). The '374 uses a clock to transfer the data at the D-inputs to the complementary outputs. Raymond |
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Re: Recreating an old board for the 7854
On Tue, Jul 20, 2021 at 09:12 PM, Clark Foley wrote:
Since we're at it: It's not 8 latches: There are 8 D-type flip-flops in a '374. Latches pass the input with one control level (the output follows the input, no clock involved) and latch their input value with the control at the other level, much like an analog sample and hold. Compare 7475 (quad latch). The '374 uses a clock to transfer the data at the D-inputs to the complementary outputs. Raymond |
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Re: Replace/Repair TM 500 Module Side Panel Latch
I have purchased TM500 plugins from reputable sellers (eg. Stewarts of Reading, Telford Electronics) and from less well-known purveyors on eBay and have found several broken latches of this type. The common "fix" seems to be to use a bit of some kind or insulated wire to wrap around the engaging parts. Since the casual observer will have no idea of this "fix" when the plug-in is in a power mainframe and in use, I can't see any problem with it. Of course, if someone were to manufacture facsimiles of the original latches and sell them at pocket-money prices, then I would be interested, but not at something like $50 each - that may be justifiable, but it is not economic, in my opinion. Others with deeper pockets may (and are welcome to) disagree.
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Colin. -----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Jeff Dutky Sent: 20 July 2021 19:36 To: [email protected] Subject: Re: [TekScopes] Replace/Repair TM 500 Module Side Panel Latch Cory, I have no experience replacing the latch, but I have a side cover that looks exactly like yours, where the latch seems to have broken internally: the slotted side rotates, but the latch side does not. I also have a TM500 "toolbox" with a solid cover and a similar latch mechanism. The latch seems to be made of two parts, the latch side and the slotted side, which snap together on a central shaft. I would expect that you could push the center shaft out of the latch side with a small screwdriver or punch, but I haven't tried this. If your latch is broken like mine, however, you don't have much to lose by experimentation (nor do I, so I will see what I can achieve). One solution would be to simply glue to the two halves of the latch together, maybe by dripping some epoxy down the hole on the latch side. This would be a fairly permanent fix (you would not be able to take the latch apart again without some amount of destruction) but I imagine a permanent fix is kind of what you are looking for. -- Jeff Dutky |
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Re: Looking for data on 9-pin Vacuum time delay relays used in old Tek-scopes
These can still be found as NOS on eBay. I bought a 6NO45T, a couple months back for around $10, for a Tek 551 I'm restoring. Turned out I didn't really need it. The main open-air PS relay that the timer triggers was sticky and had dirty contacts.
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Re: Recreating an old board for the 7854
Missed it by that much.
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Sent from my iThing, so please forgive typos and brevity. On Jul 20, 2021, at 12:13 PM, Clark Foley <clarkfoley@...> wrote: |
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Re: Replace/Repair TM 500 Module Side Panel Latch
Cory,
I have no experience replacing the latch, but I have a side cover that looks exactly like yours, where the latch seems to have broken internally: the slotted side rotates, but the latch side does not. I also have a TM500 "toolbox" with a solid cover and a similar latch mechanism. The latch seems to be made of two parts, the latch side and the slotted side, which snap together on a central shaft. I would expect that you could push the center shaft out of the latch side with a small screwdriver or punch, but I haven't tried this. If your latch is broken like mine, however, you don't have much to lose by experimentation (nor do I, so I will see what I can achieve). One solution would be to simply glue to the two halves of the latch together, maybe by dripping some epoxy down the hole on the latch side. This would be a fairly permanent fix (you would not be able to take the latch apart again without some amount of destruction) but I imagine a permanent fix is kind of what you are looking for. -- Jeff Dutky |
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Re: AA 501A Parts, DM 501A Probes
Likely no surprise to most if not all, Sphere in Canada has the AA 501A parts I need, with some caveats: the knob is a dark grey type rather than light grey as originally fitted (no big deal there), and the side panel is missing the 1/4 turn latches. I have a separate thread I started about tips for removing or repairing those, or if there are possibly replacements available.
Anyway, just wanted to follow up. Thanks again for all the helpful info! Cory Oace |
Raymond Domp Frank
Flannel Tuba
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