"Jim Wilkins" wrote in message news:sf8qtv$sir$1...@dont-email.me...
"Joe Gwinn" wrote in message
news:dbofhglf9r8p0k4k0...@4ax.com...
...............
The modulation type is QAM256, and the symbol rate on each QAM256
channel is 5120 Ksymbols per second. There are 16 downlink and 4
uplink channels. The AM component of the QAM symbols will have a
fundamental at 5 MHz or so, far above the spectrum due to a rattling connector.
.<https://en.wikipedia.org/wiki/Quadrature_amplitude_modulation>
A spectrum analyzer would not have found this problem either. I
suppose if one envelope demodulated the received RF, the chattering
would have been quite obvious - big AM noise peak in the 10 to 1000 Hz
range, or the like. I would think that it would be useful for the
modem to do this - loose connectors are pretty common I'd hazard.
...
Joe
-----------------
+5dBm is nearly half a volt. Would an unsynced scope have shown dropouts in the envelope?
--------------------
I missed that you wrote 5 dBmV, not the dBm I'm used to. 5 dBmV is too small for a good scope display.
I missed that you wrote 5 dBmV, not the dBm I'm used to. 5 dBmV is too
small
for a good scope display.
"Michael Terrell" wrote in message news:6a9b4fd2-4dcc-4b2c...@googlegroups.com...
On Saturday, August 14, 2021 at 5:39:12 PM UTC-4, Jim Wilkins wrote:
...
I missed that you wrote 5 dBmV, not the dBm I'm used to. 5 dBmV is too small
for a good scope display.
Some of the older Wavetek CATV Signal Level Meters have a built in spectrum analyzer function that you connect to an oscilloscope for the display. They are in the SAM series like the SAM III shown here:https://www.ebay.com/itm/144138486196
A cheaper way is with a SDR, a F to SMA adapter and your computer. There is good freeware to operate it from 100KHz to 1.7 GHz. https://www.ebay.com/itm/304033297816
0dBmV is 1 milivolt.
Here is a good page comparing the older DOCSIS 3.0 to the current 3.1, including the RF frequencies used: https://www.rohde-schwarz.com/us/technologies/cable_tv/docsis/docsis-technology/docsis_technology_55513.html
------------------------
Thanks. Digital encoding is one of the most complex and difficult subjects I've studied, up there with chemical Thermodynamics.
The 0 dBm (1mW, 50 Ohms) I assumed is 0.632V p-p on a scope. Usually I measured signals with a vector network analyzer.
"Michael Terrell" wrote in message news:4dd4f6ec-ef0f-470c...@googlegroups.com...
...
Here is another useful website:
http://rfcafe.com/
---------------------
Thanks. I've put solar and RF electronics aside for the time and my home project problems have all been calculating loads on steel beams, columns and their connections. That overhead gantry hoist did successfully lift and move a 2130 Lb oak log onto my sawmill. The fallen trees have all been cut into timber framing beams and very nice foot-wide knot-free boards.
"Michael Terrell" wrote in message news:4dd4f6ec-ef0f-470c...@googlegroups.com...
...
Here is another useful website:
http://rfcafe.com/
---------------------
Thanks. I've put solar and RF electronics aside for the time and my home project problems have all been calculating loads on steel beams, columns
and
their connections. That overhead gantry hoist did successfully lift and
move
a 2130 Lb oak log onto my sawmill. The fallen trees have all been cut into timber framing beams and very nice foot-wide knot-free boards.
First the wood has to dry for a year or three. I'm still dealing with maintenance I had to postpone while working overtime in another state and taking night classes. The wood was accidental, cleanup of two huge oak trees that blew down in my front yard. The straight, knot-free trunks were too
good to become firewood.
First the wood has to dry for a year or three. I'm still dealing with maintenance I had to postpone while working overtime in another state and taking night classes. The wood was accidental, cleanup of two huge oak
trees
that blew down in my front yard. The straight, knot-free trunks were too
good to become firewood.
"Michael Terrell" wrote in message news:198f2320-ca8b-4c8a...@googlegroups.com...
On Sunday, August 29, 2021 at 9:39:07 AM UTC-4, Jim Wilkins wrote:
First the wood has to dry for a year or three. I'm still dealing with maintenance I had to postpone while working overtime in another state and taking night classes. The wood was accidental, cleanup of two huge oak trees
that blew down in my front yard. The straight, knot-free trunks were too good to become firewood.
Cabinet grade oak? :)
---------------------
One side of the trunk gave 8 defect-free boards 12' long and a foot or more wide, which I'll trim to 10" wide to fit my planer and 11' 6" long to fit the wall length. The overstuffed book shelves in there now are overlapped 6' 4" long boards that will become the side wall shelves and vertical ends. I cut that oak in the late 90's because it threatened a neighbor's new pool, and converted a band saw into a smaller sawmill to salvage its clear lumber.
My father's old cast iron Shopsmith has served pretty well to make custom cabinet doors and t&g flooring.
Have you tried to disassemble pallets before?
I use 40" x 48" pallets for the floors and end walls of my firewood sheds. The pallets that don't prove strong enough have been almost impossible to
pry apart without splitting the slats, and the dirt in them dulls saw
blades, so I cut them up with a chainsaw that I can file or grind sharp. I
do a lot with recycled material but many damaged pallets are just firewood.
Have you tried to disassemble pallets before?
I use 40" x 48" pallets for the floors and end walls of my firewood sheds. The pallets that don't prove strong enough have been almost impossible to
pry apart without splitting the slats, and the dirt in them dulls saw
blades, so I cut them up with a chainsaw that I can file or grind sharp. I
do a lot with recycled material but many damaged pallets are just
firewood.
"Michael Terrell" wrote in message news:1fdc4cf8-9af4-4cc5...@googlegroups.com...
On Sunday, August 29, 2021 at 6:16:22 PM UTC-4, Jim Wilkins wrote:
Have you tried to disassemble pallets before?
I use 40" x 48" pallets for the floors and end walls of my firewood sheds. The pallets that don't prove strong enough have been almost impossible to pry apart without splitting the slats, and the dirt in them dulls saw blades, so I cut them up with a chainsaw that I can file or grind sharp. I do a lot with recycled material but many damaged pallets are just firewood.
Yes, I repaired some by taking boards from one to replace them on other pallets, and some that I rebuilt without gaps between the boards. There is a tool to make the job easier, that you can buy or make. Here is an example: https://ussolid.com/pallet-buster-head-deck-wrecker-heavy-duty-skid-buster-tool-diy.html
------------------
I just wanted to warn you in case you didn't know how difficult they could be.
To reduce the cost of my firewood storage sheds I salvage the pressure-treated beams from replaced decks, from a neighboring contractor's scrap heap, so I have several large wrecking bars and nail pullers to deal with ringed and glue nails. The prying tool I used on the pallets is a 3-foot import version of the flat Wonderbar, with its edges ground sharper. It took some softwood pallets apart successfully but the nails in many hardwood ones were glued/rusted in too tightly and broke through the slats. My main pallet source is a garden center that stores their used pallets outdoors, indoor pallets might be cleaner and easier..
The most useful ones I found were from a kitchen installer and had held counter tops. The 12' long timbers underneath are large enough that I used them as shed roof beams. The supply dried up when a new owner milked the company to death.
"Michael Terrell" wrote in message news:849f450c-c3b0-4861...@googlegroups.com...
On Monday, August 30, 2021 at 5:18:08 PM UTC-4, Jim Wilkins wrote:
The most useful ones I found were from a kitchen installer and had held counter tops. The 12' long timbers underneath are large enough that I used them as shed roof beams. The supply dried up when a new owner milked the company to death.
A HVAC company was doing a lot of work, and received a lot of equipment on those 12 foort pallets, but Covid hit before I could start picking them up. There was a local pallet maker/repair business for sale back in 2000. A guy
I worked with and I were thinking about buying it, but he backed out. It had a hydraulic powered tool to separate the boards to speed up repairs. -----------
I needed to put the roof rack on the Ford Ranger -- it's old enough to have rain gutters -- and have help loading them.
The most useful ones I found were from a kitchen installer and had held counter tops. The 12' long timbers underneath are large enough that I used them as shed roof beams. The supply dried up when a new owner milked the company to death.
Autozone has been pretty good for aftermarket parts for my '91. Somewhere there must be a demand for repairing old US vehicles. The quality/fit isn't OEM but it's been good enough as-is or with a little tweaking. I've recently replaced the headlight assemblies, outside mirrors, door window seals and a while back the radiator support, which is the front crosswise sheet metal behind the grille. This is a bad rust zone.
Autozone has been pretty good for aftermarket parts for my '91. Somewhere there must be a demand for repairing old US vehicles. The quality/fit
isn't
OEM but it's been good enough as-is or with a little tweaking. I've
recently
replaced the headlight assemblies, outside mirrors, door window seals and
a
while back the radiator support, which is the front crosswise sheet metal behind the grille. This is a bad rust zone.
"Michael Terrell" wrote in message news:9976439b-6731-4521...@googlegroups.com...
On Tuesday, August 31, 2021 at 6:34:20 PM UTC-4, Jim Wilkins wrote:
Autozone has been pretty good for aftermarket parts for my '91. Somewhere there must be a demand for repairing old US vehicles. The quality/fit
isn't
OEM but it's been good enough as-is or with a little tweaking. I've recently
replaced the headlight assemblies, outside mirrors, door window seals and
a
while back the radiator support, which is the front crosswise sheet metal behind the grille. This is a bad rust zone.
This is a thick molded black plastic piece that runs from one side of the frame, to the other to keep water from spraying up from wet roads. It would have to come from a junkyard, Autozone doesn't list a replacement, and none of the other sites that I've checked. It's just too old to make it worth stocking..
---------------------------
I patched the truck's broken plastic radiator shroud by pop-riveting a wide strip of formed sheet metal over the break. Before buying Clecos I used #5 screws as removable substitutes for 1/8" pop rivets while fitting a patch. 1/8" fender washers can spread the load on the other side. Suitable metal is galvanized steel of thickness between 22 gauge and salvaged corrugated roofing, 29 gauge, or 0.030" - 0.040" aluminum. 26 gauge steel is a good compromise between strength and ease of forming without special tools.
Stovepipe crimping pliers can form curved edge flanges and aircraft shears cut without much distortion. An anvil is useful but a length of firewood
with one end flat and a depression in the other is enough to form curved shapes, like costume armor or fender patches. I cut the depression with the end of a chainsaw. The metal bears on the edges and stretches when you
hammer in the middle, so the shape of the depression doesn't matter, it
could be the hole in the end of large pipe or maybe a brake drum. The important tool is 3-dimensional visualization of how the simple shapes you can create by hand will deform to duplicate the curves on the damaged part.
The most difficult sheet metal car part I tried to make was a stainless
steel catalytic converter heat shield. It was a good copy until I tried punching the louvers, which distorted it, so I bought a galvanized one. I probably should have formed the louvers separately and riveted them over slots.
"Michael Terrell" wrote in message news:47456d3b-318e-46e5...@googlegroups.com...
I have to dig out my ramps and see if I can drive it up on them without tearing it completely out. I think that I can cut a strip of heavy steel and drill holes to hold that side back up in place.
------------------
Would metal pipe hanging strap work?
"Michael Terrell" wrote in message news:47456d3b-318e-46e5...@googlegroups.com...
I have to dig out my ramps and see if I can drive it up on them without tearing it completely out. I think that I can cut a strip of heavy steel
and
drill holes to hold that side back up in place.
------------------
Would metal pipe hanging strap work?
When I redid the attachments for the vulnerable plastic parts under my car and truck I purposely made them weak enough to not break the harder-to-fix body sheet metal they are fastened to. The hardware is mostly nylon license plate and toilet seat bolts and nuts, except for those on the less exposed wheel well liners which are stainless.This would pull out from under the bar which would be fastened into the original holes in the chassis It is just to cover the broken mounting holes in the shield. The plastic is getting brittle after 24 years on Florida's hot roads, so it is liable to
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