开云体育

The other day, I was given an SR760, presumably with a faulty CRT. I don't know where else to go for help, so I'm turning to you guys and girls.
If someone can recommend a place to seek help, please do.
As it is, I can find different versions of a Service Manual with component lists but no schematics. All SM's for SRS equipment from the same period come without schematics. Some have them mentioned in the TOC but that's all... I think that SRS won't provide schematics if I ask but I'll do that anyway. Maybe one of you happens to have something. Even a schematic for another member of the same family could do. I'm mainly interested in the digital part.

The problem:
The CRT seems OK but there is no video coming out of the video controller; a 64 pin DIL MC63484. The Chip Select pin is never toggled by the microprocessor (80C186).
More significantly, 9 out of 10 times after a H/W reset the uP seems to remain inactive, although no NMI-, Hold- etc. pins are active at that time. The main oscillator runs and the Clock Out is always OK. 1 out of 10 times the uP generates addresses, strobes etc. - and a R/W signal but no Chip Select for the video controller nor several of the other peripheral chips. The H/W reset is clean and so are all power supplies.
It seems obvious that the uP isn't running its intended program. This could be due to address decoding-, buffer- or latch- problems or even malfunctioning UV-EPROMS, which contain the program. A malfunctioning CPU seems less likely, although a missing data- or address- line or wrong level cannot be excluded. Almost all IC's are easily obtainable but I haven't found a shop around the corner that sells the 80C186.
I haven't looked at things systematically yet with a Logic Analyzer (just a 'scope) but fully intend to do that since I think it's a nice piece of equipment, albeit with limited practical use to me. Schematics would *really* help though.

Any ideas?

Raymond

A possibly clean one-shot solution for replacing these pesky filter caps is on my mind. I was given a non operational Tek 465 just before i retired. The +55VDC rail is sitting at 41.6VDC, it is the reference voltage for the other lower rails, so they are all low too.

Assemble the capacitors between two sheets of 0.0625" vector board cord-wood style. The Sidewinder AIM_9H air-to-air missile (first all solid state electronics) used modules made this way, the AIM_9G used mini vacumn tubes. That was way back in 1974, when i was a lowly GS7 coop student at China Lake.

The volmeteric efficiency should be good and the cost of each capacitor should be very low and in stock. I would think adding a ceramic MLCC at the pcb cap through holes would be a very, very good idea. I was the designer of application specific single board computers used on some military platforms, Like the GLOBAL HAWK and M1A2.

FWIW I have also built a "silent" compressor.
Well, I had to, after switching that monster from the DIY store on the
first time I knew I wouldn't put up with that racket.

I took a refrigeration compressor, a slightly larger one from a
commercial unit, and cut it open to clean it (it was rusted solid),
and replaced the oil with regular motor oil. You really need to
replace that oil since refrigeration oil is hygroscopic and everything
will rust like crazy if you run it in air.
I simply cut open the case with an angle grinder, and later sealed it
back up with a rubber strip and a metal band.
Mine is from 1970 or thereabouts, made in Scotland of all places. The
old cast iron ones are better than the aluminium ones, in my mind
anyway.
It fills up the tank of the noisy compressor, but has it's own
pressure switch, I just didn't have a suitable pressure vessel at the
time.

Refrigeration compressors typically don't have piston rings, so they
introduce more oil into the the air than other piston compressors. But
it tends to settle out in the tank and not cause any issue.

Some commercial silent compressors look suspiciously like
refrigeration compressors anyway, with an added sight glass for the
oil level.
I guess a scroll compressor from a modern AC unit would be neat too,
but those are usually higher powered and not really silent.

ST

On Sat, 28 Jul 2018 08:26:52 -0700, you wrote:

If you have a dual channel scope, preferably one that does storage, or
a digital scope, or a logic analyzer, then you're looking for a
coincidence of the bus going to a 1 or 0 (at that output pin) when the
dir and OE are enabled on the driver chip. Alternatively, a chip
analyzer clip (HP, don't think that Tek ever made any) would work, and
you're looking for errors. Another option is to hold the reset pin
down on the processor, then using an HP logic pulser, see what the
output pin of the chip (bus side) does.

Your other option is to replace the chip. Note that it might be a
reasonable assumption that this particular board may be programmed to
ignore that switch, either through revision or because another option
is not enabled.

Guessing, though.

the main problem in finding this is that the switch is likely sampled
only on bootup. Hence, a relatively rare event unless you can put the
processor in a signature analysis mode (which cycles all the address
lines), that would give you a repeating pattern that would not require
a digital or storage scope.

If you had a signature analyzer, and you had the right signatures at
that chip, that would also be beneficial to know. They'd have to be
at that pin with the switch in a particular position, though.

Harvey

[Edited Message Follows]

495P A54 Memory Board Troubleshooting: continued

At some risk of wearing out my welcome here with multiple posts on this topic, however, I am seeing this instrument and its various circuits for the first time and can use as much experienced advice as I can get.

Situation:

495P SA s/n B030xxx: Purchased with the representation by the seller that the A54 memory board is defective. SA boots up in somewhat expected fashion, except that on-screen message identifies it as a 492AP, not a 495. However, substantial functionality is apparent but with several error messages; the initial screen is what one would expect for a 492AP and the cal signal produces typical SA traces.The microcomputer is running the 492AP firmware rather than the 495 firmware. Choice of firmware to run is based DIP option switch S1050 on the A54 memory board. When I install a known good memory board with option switch SW4 set to OPEN and all other option switches set to CLOSED, SA boots up with correct indications and no error messages; when I set option switch SW4 to CLOSED with all others closed, SA boots up as a 492AP just as it does with the defective A54 memory board.

Analysis:

After consideration of the symptoms and review of block and circuit diagrams in the service manual, it appears that the microcomputer controller in not reading the option switch setting correctly at boot up. IOW, it reads SW4 as CLOSED regardless of the switch position, and runs the 492AP firmware accordingly.

Possible causes:

Defective DIP options switch: Tested these with ohmmeter and readings are consistent with a working switch: 0 ohms closed, about 11K ohms open, which is close to what the circuit diagram suggests. These readings match those on the known good board. Can likely rule out switch on this basis.

Defective address decoder chip(s): The option switch is treated as a memory location in the controller I/O address space. Three decoder chips (U2045, U3040, U3045) are used to decode the option switch address and generate an enable signal to place the option switch settings on the 8 bit data bus to be read by the processor during boot up. This happens only once at boot up for a few microseconds at most, so somewhat difficult to trace. Decoders U2015 and U3040 are also used for other purposes on this board, and since the board is mainly functional, these dont seem to be candidates for replacement. U3015 decoder is used only for the purpose of enabling the option switches to the data bus, and if defective, would account for the problems I am seeing.

Defective U2050 74LS244 tri-state buffer: this chip enables the settings of the option switches onto the 8 bit data bus when the appropriate address on the address bus is detected by the decoder chips. If this chip is defective, it would very likely be the source of the problem.

Damaged circuit board: I have inspected this carefully with a magnifier and see nothing of concern so far. Have also checked the continuity of traces throughout the switch/decoder/buffer circuits and find no problems. The three 10mfd electrolytics on this board have been replaced.


Diagnosis:

Its probably not a defective option switch or defective U2045 or U3040 decoder, and probably not a circuit board problem. My best guess so far is a defective U3045 decoder or a defective U2050 tri-state buffer, with the latter perhaps more likely.

I welcome any insights/advice on this topic.

Rick
K8EZB

On Sat, 28 Jul 2018 07:03:54 +0200, you wrote:

I see they still use the RF tips where you can't adjust the temperature.
That has always been a deal breaker for me (I adjust the temperature
quite a lot) but I think for desoldering it would be fine.

I've never found it to be a problem, I just swap tips as needed for
different temperatures and situations.

The price is to be expected, it's actually cheaper than the other high
end desoldering stations, and it's someone else's money.
(For now, I might need one at home too if it is that great, you know
how it goes ;-)

Go look for used, of course. For me, it's NEVER someone else's money
unless I get something used, and it's still at least partly my money.

I'm not keen on the bent solder tube that directs the solder downward.
I hope that doesn't plug up too much.
80W seems a bit on the low side.

Possibly, but heat efficiency and transfer are unknown factors in
comparison to other wattages.

It's nice that they employ a blind designer, it's always good to see a
company support the disabled.
(Seriously that thombstone power station with the 2x16 display is ugly
as f, but at this point I really don't care as long as it works).

If it offends you, you could always repackage it, I suspect.

Not aware of anyone who makes an equivalent. Thermaltronics has much
the same scheme.

Harvey

ST

On Sat, Jul 28, 2018 at 6:25 AM, Bruce Lane <kyrrin@...> wrote:

On 27-Jul-18 20:41, stefan_trethan wrote:

I wasn't familiar with the Metcal MX-DS1 and it does look rather good, thanks!

Do either one of you, or maybe both, currently have that system?
If so, please tell me which model, especially also of the control station.

<snippage>

I have the Metcal DS1, as well as two sizes of soldering pencil
(standard and micro-fine) and the hot tweezers. I use them with the
MX5000 power unit.

Honestly, I consider it the best soldering/desoldering tool investment
I ever made. The desolder gun beats the pants off the Pace unit I used
to use.

The only possible downside is you'll need a source of clean, dry
compressed air ('shop air') to make the Metcal unit do its thing. To
take care of this, I also bought a mini compressor from California Air
Tools (one of their ultra-quiet series).

Be prepared to spend between $750-$1100. Metcal makes some of the best
stuff around, but it doesn't come cheap.

Keep the peace(es).

--
---
Bruce Lane, ARS KC7GR

kyrrin (at) bluefeathertech dot com
"Quando Omni Flunkus Moritati" (Red Green)

Eric I'm curious on your air compressor since the metcal seed 90 PSI
can you contact me off group and tell me how you build it thanks

On Fri, Jul 27, 2018, 9:28 PM EricJ via Groups.Io <wyzkydd2358=
[email protected]> wrote:

Yes Stefan, I have mine, still use it. I'm using a Metcal PS2E-01 power
unit with mine. The power units can be had on eBay pretty cheap these days,
and since this older unit produces the same 13MHz frequency as the newer
ones a good Metcal iron will plug right in and work with the same power
supply also. Happy to answer any questions that I can.
Regarding the air line length, I use mine straight from a homemade
"silent" compressor with a 5 gallon tank next to my bench at the end of an
air line that may be 6 feet long, so no issues of that sort for me. I also
use the tip cleaners frequently and thus have not really had to battle many
clogging issues.
--Eric
Sent from my Samsung Galaxy smartphone.
-------- Original message --------From: stefan_trethan <
stefan_trethan@...> Date: 7/27/18 10:41 PM (GMT-06:00) To:
[email protected] Subject: Re: Wow Radio Shack desoldering Iron Best
review ever, Re: [TekScopes] 466-464 stray wire
I wasn't familiar with the Metcal MX-DS1 and it does look rather good,
thanks!

Do either one of you, or maybe both, currently have that system?
If so, please tell me which model, especially also of the control station.

I have to read up on it and if any questions remain I hope I can put
them to you.
Information from actual users is often much more valueable than from
sales staff ;-).

See, a rant sometimes isn't entirely futile.

ST

On Sat, Jul 28, 2018 at 1:50 AM, tom jobe <tomjobe@...> wrote:

I have had that same Metcal MX desoldering system for years, and I found
that being connected with a fairly long air hose (25 feet?) limited the

air

pressure available to the desoldering gun used to make its vacuum. An old
Freon tank of a few gallon capacity was turned into an air pressure
reservoir and installed between the Metcal desoldering gun and the air
pressure line. That improved things a lot as there was now full air

pressure

available at the instant you pulled the trigger.
Keeping the nozzles clear of solder is the main problem, but frequent

use of

the available Metcal tip cleaning rods can partially keep you on top of

that

problem.
The Metcal cleaning rod set is just a customized version of the same tip
cleaners a welder uses to keep his gas welding tips clean, but the Metcal
set of cleaning tips are longer and sized to the standard Metcal tip
diameters.
The only other real issue is keeping the 'business end' of the

desoldering

tips 'wetted' with fresh solder, and I never have solved that problem.
tom jobe...



On 7/27/2018 3:27 PM, EricJ via Groups.Io wrote:

Yes, the good venturi models have much better suction (high volume) and
it's instant. I've got a Metcal MX-DS1, it's awesome. Totally agree on

the

rest of your points also. Clogged nozzles will make any desoldering gun

work

like crap.
--Eric
Sent from my Samsung Galaxy smartphone.
-------- Original message --------From: Harvey White
<madyn@...> Date: 7/27/18 2:19 PM (GMT-06:00) To:
[email protected] Subject: Re: Wow Radio Shack desoldering Iron Best
review ever, Re: [TekScopes] 466-464 stray wire
On Fri, 27 Jul 2018 14:47:33 -0400 (EDT), you wrote:

I've used my Radio Shack solder sucker (not the bulb but the
spring-loaded cylinder version) with pretty good success but I have

lifted a

couple of pads along the way. I really, really need to get something

like

the Hakko. I watched a video this morning where it was used to

desolder a

component board from another board that had around eight pins soldered

with

through-holes to the larger board. After the Hakko was finished (in

less

than a minute total time), the secondary board practically fell out.
Impressive.

Selecting the tip temperature is important (where this adjustment is
available).

Heating the joint all the way through is also critical. Don't be
afraid to add solder so that no air gets sucked in.

The ones with the built in pumps are most convenient, but I wonder if
the ones that run off compressed air (bernouli principle) don't have a
sharper vacuum pulse.

The right tip diameter is also important.

Cleaning out the tips and filters is pretty critical, no suction, no
desoldering.

Harvey

Thanks,
Barry - N4BUQ

----- Original Message -----

From: "Ray Burke" <burke.ray@...>
To: [email protected]
Sent: Friday, July 27, 2018 9:10:46 AM
Subject: Re: Wow Radio Shack desoldering Iron Best review ever, Re:
[TekScopes] 466-464 stray wire

The Radio Shack Desoldering bulb is useless because you cant get the
tips any
more, no more Radio Shack. I have used the Radio Shack Desoldering
bulb,
(have one). Solder Wick, Solder Suckers and other tools, while they

are

cheap, they do cause damage to the circuit boards with pulled pads,
through
holes, and other problems, ( I have used them and damaged my boards).
Don't
use any of the cheap alternatives, if you want to save the circuit
boards.
Use at least a good Desoldering gun or station. Use at least a

Hakko

FR-301 which I just bought, or a better Hakko Desoldering station,

there

are
others that are more expensive like Pace, Metcal, which I used at

work.

I
just used it to repair my wifes monitor that died with no power, and
opened
it up and found about three bulging capacitors, replaced all eight on
the
power supply, and fixed it. After getting the caps at Fry's it only
took
me about 20 minutes to change all eight, love my new Desoldering

gun,

NO
PULLED PADS. One other thing is manufacture support, Hakko is the

best.

I
got a desoldering station from my work, which they didn't want any

more

and
Hakko had the tips for the thing. Now you could get some cheap

Chinese

knockoff but support may not be their in a few years, or at all.

Buy

at
least a Hakko and you won't be disappointed. The other main

desoldering

companies are more expensive. You could check out the tear apart

videos

of
the www.EEVBlog with Dave Jones.

On Thursday, July 26, 2018 11:36 PM, Michael A. Terrell
<mike.terrell@...> wrote:


I started working in a TV shop at 13, in 1965. One older tech was a
fountain
of practical knowledge. I wasn't old enough to open an account at

the

local
parts house, so he would buy things for me so Ii didn't have to go
through
our boss and pay his markup. He bought me my first desoldering iron
which
was a professional version of that Radio Shack version. It was made
by
Endevco, and it was almost $40 which was a lot for a kid making a
buck an
hour after school. He was also the one who got me started on Ersin
Multicore solder. I've never regretted paying a little extra for

good

solder, because there was very little waste.

We handed the resale of a wave solder machine for Lockheed Martin

around

1990, along with other process equipment after they shut down a
production
line in one of the Orlando plants.

Microdyne was still using the same grade of paste solder they tarted
with,
even though the SMD parts were a lot smaller than the first they

used. I

had
to fight with Manufacturing engineering to buy a type with smaller
solder
balls and a RMA flux. The fine pitch ICs (IE: MC68340) came out of the
early
ovens with unmelted solder balls under the ICs, and the 0402 passives
were
tombstoning. They had spent a wad on that Heller oven, but the quality
hadn't changed. Once we had better solder, we could refine the reflow
profiles. That eliminated over 95% of the reflow problems within a few
months, as they continued to refine the profiles.

Did you build much equipment for your Amateur radio hobby? I went a
different
route, into broadcasting. Not many hams ever got to pump out 5MW EIRP

of

RF
from a 1700 foot tower. :)

Michael A. Terrell


-----Original Message-----

From: Chuck Harris <cfharris@...>
Sent: Jul 26, 2018 11:59 PM
To: [email protected]
Subject: Re: Wow Radio Shack desoldering Iron Best review ever, Re:
[TekScopes] 466-464 stray wire

I have minimal experience with industrial soldering machines. I
was a kid back in 1970, and a ham, and getting a job working for
DEI was like being let loose in a candy shop. I did a ton of
odd jobs after the child labor bureau made me stop doing all of
their silver and gold plating. I was a sponge, and soaked up every
process or technique I was exposed to. Which was a lot. I did
etching, plating, drilling, KPR, soldering, helped set up the
one-off machines that made standoffs and rivets... moved safes,
carried trash, pushed a broom... but I digress.

Nobody that I am aware of was using reflow ovens back in 1970.
Everything I saw was either through-hole, or was simple stuff
that was hand soldered on one of the teflon based pcb materials.

But I can only talk to what DEI, Nems-Clarke, and Vitro were did,
and also what a PCB manufacture/build/assemble house I worked at
later was doing.

I just did a search, and the only 80/20 alloy I could find was a
Pb80/Sn20, which has a solidus temperature of 183C and a liquidus
temperature of 280C. That is as compared to 63/37 which is 183C.

Pb80/Sn20 would be wonderful for operations where you needed to
sculpt the solder, like a car fender, or the terminals on very high
voltage circuitry. It would also be useful for soldering terminals
that might be later soldered with 63/37, such as the internal
connections
on a modular mixer.

-Chuck Harris

495P A54 Memory Board Troubleshooting: continued

At some risk of wearing out my welcome here with multiple posts on this topic, however, I am seeing this instrument and its various circuits for the first time and can use as much experienced advice as I can get.

Situation:

495P SA s/n B030xxx: Purchased with the representation by the seller that the A54 memory board is defective. SA boots up in somewhat expected fashion, except that on-screen message identifies it as a 492AP, not a 495. However, substantial functionality is apparent but with several error messages; the initial screen is what one would expect for a 492AP and the cal signal produces typical SA traces.The microcomputer is running the 492AP firmware rather than the 495 firmware. Choice of firmware to run is based DIP option switch S1050 on the A54 memory board. When I install a known good memory board with option switch SW4 set to OPEN and all other option switches set to CLOSED, SA boots up with correct indications and no error messages; when I set option switch SW4 to CLOSED with all others closed, SA boots up as a 492AP just as it does with the defective A54 memory board.

Analysis:

After consideration of the symptoms and review of block and circuit diagrams in the service manual, it appears that the microcomputer controller in not reading the option switch setting correctly at boot up. IOW, it reads SW4 as CLOSED regardless of the switch position, and runs the 492AP firmware accordingly.

Possible causes:

Defective DIP options switch: Tested these with ohmmeter and readings are consistent with a working switch: 0 ohms closed, about 11K ohms open, which is close to what the circuit diagram suggests. These readings match those on the known good board. Can likely rule out switch on this basis.

Defective address decoder chip(s): The option switch is treated as a memory location in the controller I/O address space. Three decoder chips (U2045, U3040, U3045) are used to decode the option switch address and generate an enable signal to place the option switch settings on the 8 bit data bus to be read by the processor during boot up. This happens only once at boot up for a few microseconds at most, so somewhat difficult to trace. Decoders U2045 and U3040 are also used for other purposes on this board, and since the board is mainly functional, these dont seem to be candidates for replacement. U3045 decoder is used only for the purpose of enabling the option switches to the data bus, and if defective, would account for the problems I am seeing.

Defective U2050 74LS244 tri-state buffer: this chip enables the settings of the option switches onto the 8 bit data bus when the appropriate address on the address bus is detected by the decoder chips. If this chip is defective, it would very likely be the source of the problem.

Damaged circuit board: I have inspected this carefully with a magnifier and see nothing of concern so far. Have also checked the continuity of traces throughout the switch/decoder/buffer circuits and find no problems. The three 10mfd electrolytics on this board have been replaced.


Diagnosis:

Its probably not a defective option switch or defective U2045 or U3040 decoder, and probably not a circuit board problem. My best guess so far is a defective U3045 decoder or a defective U2050 tri-state buffer, with the latter perhaps more likely.

I welcome any insights/advice on this topic.

Rick
K8EZB

Hi, I have a 7L12 and a 7L14 and I made my self the same question. With two prescalers and two counters is possible to make a circuit and write in the readout system. Anyway I?m searching for a TR502 system with counter.

Regards

Miguel

-----Mensaje original-----
De: [email protected] [mailto:[email protected]] En nombre de Gudjon Gudjonsson
Enviado el: sábado, 28 de julio de 2018 15:54
Para: TekScopes
Asunto: Re: [TekScopes] 7L13, more exact frequency readout

Thanks for the answer Chris

You made things a bit clearer.

I don't need accuracy, just stability. I do have a frequency source that I can use to tune into the frequency I'm after but then I would like to keep this stable.

In zero span mode I should be able to use a frequency counter on the 1st LO. I found one for frequencies up to 5.8GHz for a reasonable price.

In scanning mode I will try to read the DVM input voltage (U2140) with a more precise external DVM and see if I can use it for some improvement.

I will test and let you know if it works.

Regards
Gudjon

I used to feel the same regarding temperature adjustment, but with the newer high wattage PID controlled irons I haven't found it necessary to mess with temperature much at all, even though my main iron is adjustable. My go-to is an Ersa iCon-1, which peaks at 150W. It has never failed to wet a joint out nearly instantly with the correct tip. The Metcal is pretty much the same from what I hear. These days with the better irons correct tip geometry/size is more critical than temp adjustment IMO, and the Metcal has that covered in spades. If you end up really wanting to change temp, it's as easy as sliding out the lower temp tip and sliding back in the high temp tip.
--Eric
Sent from my Samsung Galaxy smartphone.

I would like two boards please.

I'm good in QRZ

W0MPM

On Fri, 27 Jul 2018 21:25:23 -0700, you wrote:

You can sometimes find Metcal power supplies at hamfests. You can
find various varieties, the older ones are least expensive. The newer
ones may drive more than one wand at a time, and have a display. The
ones I have do not have readouts, and only one has a switch.

Thermaltronics makes plug-in equivalents (available on amazon.com)
that are significantly less expensive than the Metcal tips, but come
in less variety.

Note that you can get (for tips) temperature ratings in 600, 700, and
800 degrees (all fixed), soldering and desoldering varieties. Pay
special attention to the number on the desoldering tips, since some
are for different packages and not all will work on TQFP, for
instance, even though they look as if they do. The SMT part
desoldering tips are particularly useful at times, but need to be
ordered for each size, say 1206, 0805, etc.

The desoldering tweezers are reportedly nice (but quite expensive, so
I don't have any).

I do have the desoldering system, so finding a silent air compressor
becomes a requirement. I think I have one somewhere.

You'll want the stands as well. A pace wand stand *may* fit the
wands, but you do have to be somewhat careful.

Harvey

On 27-Jul-18 20:41, stefan_trethan wrote:

I wasn't familiar with the Metcal MX-DS1 and it does look rather good, thanks!

Do either one of you, or maybe both, currently have that system?
If so, please tell me which model, especially also of the control station.

<snippage>

I have the Metcal DS1, as well as two sizes of soldering pencil
(standard and micro-fine) and the hot tweezers. I use them with the
MX5000 power unit.

Honestly, I consider it the best soldering/desoldering tool investment
I ever made. The desolder gun beats the pants off the Pace unit I used
to use.

The only possible downside is you'll need a source of clean, dry
compressed air ('shop air') to make the Metcal unit do its thing. To
take care of this, I also bought a mini compressor from California Air
Tools (one of their ultra-quiet series).

Be prepared to spend between $750-$1100. Metcal makes some of the best
stuff around, but it doesn't come cheap.

Keep the peace(es).

Oops, got the URL wrong!

First, the markings for C1115 and C1132 are mixed up in all Tektronix documentation.

I have created a page on the TekWiki for this sort of info. If anyone has any helpful info, this would be a great place to add it. If you can't add it, send it to me (here on the group) and I'll add it. This includes pictures and instruction docs.

So I can get the linkage right, can someone confirm which 'scopes use this same PSU please? Is it just 2245, 2445A, 2465, 2465A, and 2465B?

Brian.

Thanks for the answer Chris

You made things a bit clearer.

I don't need accuracy, just stability. I do have a frequency source
that I can use to tune into the frequency I'm after
but then I would like to keep this stable.

In zero span mode I should be able to use a frequency counter on the
1st LO. I found one for frequencies up to
5.8GHz for a reasonable price.

In scanning mode I will try to read the DVM input voltage (U2140) with
a more precise external
DVM and see if I can use it for some improvement.

I will test and let you know if it works.

Regards
Gudjon

Barry,
Can you please send me a pdf of the PCB? It will be easier for me to get
them fabricated in VU Land locally.
Kind regards and 73,
Sudipta Ghose VU2UT

--
One of those ... ...

Hi Barry,


I am not sure that you receive my previous e-mail, so I copy the text hereunder.



Great, thank you. When I live in Miami, my preferred carrier was USPS. Prices was a that time quite reasonable, but I know with the decrease of the postal volume prices going increasing every where.
I try to have a look over the internet on the USPS site and prices look just stratospheric... May be if you use a bobble wrap envelop and send it as a regular letter the price will be acceptable...otherwise the other option is to buy 5 boards and keep the extra ones for future need ( in this case the shipping cost per board will be better).



Please let me know.


For payment did you accept Paypal?

Have a nice day.

Thanks,
Victor

You might even think about doing a ringing test on the transformer, I've
replaced a few of these over the years.

-Bert

Hi Bert,

the "ringing test on the transformer", is that a way of testing the windings of the primary transformer?
Do you have any information about this test?

Because my scope is running fine on an external 43VDC, and I am still waiting for the FET's and Diode's, if there is a way of testing the primary transformator I would like to do so.
I can easily remove the transformer and apply some sinusoidal signal to it, is there any data available in terms of no. of windings, resistance per winding, etc. for this trafo?

Un saludo,

Leo

I mostly adjust the temperature for specific tasks rather than for
more power (I agree that is not a good workaround anyway).
For example to tin enamel wire I need to crank it up so the laquer
burns off, and when I want to make solder bridges I need it a little
colder.

I specifically bought the old style JBC stations because of that,
where you can simply twist the knob to where you want with no fuss,
not like the new ones with up/down buttons and a menu.

So for the regular iron I don't think I would be too happy with
changing tips for temperature, and the thermal performance of the JBC
stations is excellent anyways. Also I have the JBC tweezers and
autofeed iron already (these days about half the time I solder with
the autofeed).

But for desoldering I don't think that is an issue, I never change the
temperature on my desoldering station, not even the tip size all that
much.

I would probably still get the dual Metcal station anyway because the
price difference is negligible, and have another iron handy maybe with
some particular tip. It doesn't look like they have any other tools
that would benefit me over what I already have.

Metcal is not as well supported here as the other brands, but my
regular supplier does carry them, so I should be able to get a demo
unit.

ST

On Fri, Jul 27, 2018 at 11:18 PM, Gudjon Gudjonsson wrote:

I'm using my 7L13 to measure bursts of 480 MHz signals.
It works pretty well but I miss a more precise frequency readout.
Is it possible to make a better frequency readout?

Is it difficult to either:
1. Mix the first LO with an external 2095MHz source and insert into a
frequency counter.

This is basically what the TR502 and similar tracking generators do. They're designed to solve exactly this problem. However, just mixing with the first LO isn't enough. At frequency/div settings less than 200kHz/div (I think) the first LO is fixed and the second LO is swept, so you need to use both LOs to extract the signal frequency. So if 'precise' to you means better than 100kHz accuracy, you need to take both LOs into account.

2. Replace the YIG oscillator with a digital signal source.

I wonder - maybe this could work, if you can find a signal source covering 2.1-3.9GHz. However, you'll need to measure the second LO too.

The cheapest way of measuring the signal frequency is probably just to measure both LOs with frequency counters and then do the math, as they say. I found that my old but great HP 5245L counter with a 5254A 0.3-3GHz frequency converter plugin (plugin was $20 on ebay - there are still bargains out there!) does a fine job of measuring the local oscillator frequencies.

Chris

Hi list

I'm using my 7L13 to measure bursts of 480 MHz signals.
It works pretty well but I miss a more precise frequency readout.
Is it possible to make a better frequency readout?

Is it difficult to either:
1. Mix the first LO with an external 2095MHz source and insert into a
frequency counter.
2. Replace the YIG oscillator with a digital signal source.

As you may have found out by now, I am a bit of a novice in RF :)

Regards
Gudjon