开云体育

One important thing to remember is that CB channels below 24 are NEITHER contiguous nor numerically ordered. So to repurpose these switches, you might set up an LED matrix to show continuity per switch position.
I’ve seen a few switch tables for CBs but it was decades ago. I’m pretty sure but not positive that all 40-channel CBs used a switched digital PLL and VCO arrangement and not the “rock crusher” crystal mixer common with most 23-channel rigs.
FWIW the digitally controlled rigs used an octal +1 switch matrix on the VCO, but some had hex inputs. Some also had a ROM to block non-permitted frequencies. Defeating the ROM was non-trivial and required significant surgery.
If CBTRICKS.com is still online, you may be able to garner more info there. Especially if you are converting CBs to other bands, you want to buy their DVD set if it’s still available.
It’s much faster to search a DVD than to download from their website, especially since some misguided anti-CB dweebs continue to engage in DoS attacks against them, 30 years after the CB wars ended.
73
Jim N6OTQ
Sent from my quenched-gap spark transmitter.

"Be worth obtaining an adjustable power supply if you plan on doing many
board repairs. Why risk damaging boards?"

Absolutely! And use a PS with an adjustable current limit and set the
limit only slightly higher than the amount of current that you expect the
item under test to draw. I used to keep notebooks full of notes about
various repairs including how much power that model item actually drew
under various operating conditions. I also STRONGLY suggest using a GOOD
quality PS like those from HP, Lambda, etc and not one of cheap Chinese
ones. Many of the cheap PSs contain large filter caps on their output in
oder to reduce AC ripple but those large caps can provide enough power to
fry your electronics before their *slow* current limiters can kick in.
GOOD PSs are expensive when new but used ones are available just about
anywhere (at least in the US and Canada) and are usually very cheap (~$20)

On Sat, May 1, 2021 at 8:45 PM Bill via groups.io <ko4nrbs=
[email protected]> wrote:

Be worth obtaining an adjustable power supply if you plan on doing many
board repairs. Why risk damaging boards?

Bill

Paul,

I used to haul large CRTs (21" computer displays) this way, which are admittedly less finicky than an old tek scope, at least they never seemed to care about orientation, and I would seatbelt them in. They were all deep enough that the seatbelt was near its limit, so they were held in pretty securely that way. For this, however, I will try to pick up some bungie cords or something, to get a good strap around the seat back. I was going to bring some larger blocks of closed cell foam to give it some cushioning in case I had to put it in back, but I can use the same foam to wedge against the dash in front.

I'm still a little worried about the CRT mounting in the case. I can't seem to find the thread now (and maybe it wasn't in this group; maybe it was in a Facebook group I also belong to) where someone had moved a 500-series scope but some part of the CRT mounting hardware had failed and the neck had shattered. I'd really like to avoid that sort of tragedy if at all possible.

-- Jeff Dutky

I am not sure if you will agree, but I think eBay had a major impact on
hamfests. For me, they were always a great place to buy and sell
electronics. I did sell a couple of Tek scopes at the Gaithersburg Hamfest
years ago. One I probably let go for too little - a completely working 556
dual beam with 1A4 and 1A1 plug-ins. I also bought Tek stuff - mostly
plug-ins. A couple of the hamfests had a place where you could plug stuff
in to see if it worked. The reputable sellers would let you do this.

I want to ones mostly on the east coast plus a couple in southern
California when I happened to be there when one of the hamfests was
running. Many of my friends with whom I would go to hamfests also think
that eBay cut into hamfest participation. One thing we noticed was that
many of those both selling and purchasing would cite eBay prices; buyers
would say, “Well, I can get it for less on eBay” and sellers, “On eBay
these go for much more.” Of course there were comebacks for these - “So,
I’ll go buy it on eBay instead of from you” - “So, sell it on eBay then.”

Hamfests were another resource for buying and selling electronics. The
large Dayton hamfest (I never got to this one) has gone with virtual
sessions this month, but no fleamarket. Maybe next year - let’s hope.

Steve Horii


On Sat, May 1, 2021 at 11:10 Dennis Tillman W7pF <dennis@...>
wrote:

Auctions have been around since at least 500 B.C. since they promise to
fetch as high a price as possible for the seller while at the same time
offering to the buyer the prospect of buying items at bargain prices or
perhaps buying items that would be difficult to buy in any other way.

Complaining about the latest changes in eBay's fees, or requirements

etc.,

as many members are doing, is a waste of time. The auctioneer, eBay in

this

case, is entitled to collect a fee for providing the auction venue and

for

running it. The shipping companies all charge virtually the same price
(monopolistic competition) so there is nothing you can do about that fee.

A far more useful way to spend your time is learning how to get what you
want at the lowest price (if you are a buyer) or how to sell it at the
highest price (if you are a seller). Almost everything you need to know

to

be more successful can be found in "Snipers, Shills, & Sharks : eBay and
Human Behavior", by Ken Steiglitz, ISBN-13: 978-0-671-12713-2 and

ISBN-10:

0-691-12713-1, 381.177015193-dc28.

Dennis Tillman W7pF

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of -
Sent: Friday, April 30, 2021 10:30 AM
To: [email protected]
Subject: Re: [TekScopes] OT! OT! --- E-bay fee change -- OT! OT! Cross
posted with HP group.

Dennis,

I agree with everything that you said. However I think that what

people

truely object to are the *never-ending* price increases from E-bay. PLUS
all of the other charges (PayPal and Global Shipping for example) for
services that they force buyers and sellers to use. Personally, I've

been a

buyer and a seller on Ebay since the first year that they started I've

seen

their fees rise from a FLAT 2% to whatever the combined totals are

today. I

quit sellling on Ebay about 5 years ago after I sold ONE item for $200

and

was charged slightly over $22 for Ebay and PayPal only and shipping not
included. But as you point out Ebay is a private company and isn't

beholden

to it's buyer and sellers so they have decide if they want to use it or
not. However, as far as I'm concerned, E-bay is still the only serious
game in town if you want to sell something for a decent price. And it's
also usually the only place where most individuals can buy the

specialized

test equipment or other items that we desire.

Overall; despite it's constant cost increase, I'm very pleased to have
seen the rise of Ebay. I've made a pile of money selling TE and other

items

that I would never have been able to sell without them and I've also been
able buy books, TE and some other items that I would never been able to
find, or have been able to afford, from the old regular TE suppliers such
as Tucker Electronics.




--
Dennis Tillman W7pF
TekScopes Moderator

So by protection diode, you're not talking about over-voltage, you're talking about accidentally driving another source. So a forward biased diode that would prevent current into the power supply.

That much I got. No, don't drive into the PS, either setup in parallel, or attempting to drive some other source. Yeah, I wouldn't do that. (On purpose).

Dave


On Saturday, May 1, 2021, 02:52:35 PM PDT, Harvey White <madyn@...> wrote:
Definitely.? Most power supplies take a very dim (as in permanently off)
view of reverse voltage applied to their terminals.? Most also don't
like to be tied to another power supply in parallel unless designed for it.

If you're going to charge a battery with a Chinese (or many other types)
power supply, put a series diode in so that the supply can't be fed by
the battery.

Harvey


On 5/1/2021 5:38 PM, Ed Breya via groups.io wrote:

Be sure to add an external reverse protection diode across each output, in case there isn't one built in.

Ed

Any advice on what to check before transporting a 500-series scope? I know
that there's some kind of clamp or brace for the CRT on these old scopes
that can deteriorate with time. I'm planning to takes some closed-cell foam
sheets tto brace the CRT if necessary, but I haven't found any pictures of
how the CRT is mounted and would like some advanced warning.

I'll be picking the scope up tomorrow (Sunday, May 2nd), so quicker
answers would be appreciated.

Thanks.

-- Jeff Dutky

Paul,

I used to haul large CRTs (21" computer displays) this way, which are
admittedly less finicky than an old tek scope, at least they never seemed
to care about orientation, and I would seatbelt them in. They were all deep
enough that the seatbelt was near its limit, so they were held in pretty
securely that way. For this, however, I will try to pick up some bungie
cords or something, to get a good strap around the seat back. I was going
to bring some larger blocks of closed cell foam to give it some cushioning
in case I had to put it in back, but I can use the same foam to wedge
against the dash in front.

I'm still a little worried about the CRT mounting in the case. I can't
seem to find the thread now (and maybe it wasn't in this group; maybe it
was in a Facebook group I also belong to) where someone had moved a
500-series scope but some part of the CRT mounting hardware had failed and
the neck had shattered. I'd really like to avoid that sort of tragedy if at
all possible.

-- Jeff Dutky

Auctions have been around since at least 500 B.C. since they promise to
fetch as high a price as possible for the seller while at the same time
offering to the buyer the prospect of buying items at bargain prices or
perhaps buying items that would be difficult to buy in any other way.

Complaining about the latest changes in eBay's fees, or requirements etc.,
as many members are doing, is a waste of time. The auctioneer, eBay in this
case, is entitled to collect a fee for providing the auction venue and for
running it. The shipping companies all charge virtually the same price
(monopolistic competition) so there is nothing you can do about that fee.

A far more useful way to spend your time is learning how to get what you
want at the lowest price (if you are a buyer) or how to sell it at the
highest price (if you are a seller). Almost everything you need to know to
be more successful can be found in "Snipers, Shills, & Sharks : eBay and
Human Behavior", by Ken Steiglitz, ISBN-13: 978-0-671-12713-2 and ISBN-10:
0-691-12713-1, 381.177015193-dc28.

Dennis Tillman W7pF

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of -
Sent: Friday, April 30, 2021 10:30 AM
To: [email protected]
Subject: Re: [TekScopes] OT! OT! --- E-bay fee change -- OT! OT! Cross
posted with HP group.

? Dennis,

? ? I agree with everything that you said. However I think that what people
truely object to are the *never-ending* price increases from E-bay. PLUS
all of the other charges (PayPal and Global Shipping for example) for
services that they force buyers and sellers to use. Personally, I've been a
buyer and a seller on Ebay since the first year that they started I've seen
their fees rise from a FLAT 2% to whatever the combined totals are today. I
quit sellling on Ebay about 5 years ago after I sold ONE item for $200 and
was charged slightly over $22 for Ebay and PayPal only and shipping not
included. But as you point out Ebay is a private company and isn't beholden
to it's buyer and sellers so they have decide if they want to use it or
not. However, as far as I'm concerned,? E-bay is still the only serious
game in town if you want to sell something for a decent price. And it's
also usually the only place where most individuals can buy the specialized
test equipment or other items that we desire.

? ? Overall; despite it's constant cost increase, I'm very pleased to have
seen the rise of Ebay. I've made a pile of money selling TE and other items
that I would never have been able to sell without them and I've also been
able buy books, TE and some other items that I would never been able to
find, or have been able to afford, from the old regular TE suppliers such
as Tucker Electronics.




--
Dennis Tillman W7pF
TekScopes Moderator

Paul,

I used to haul large CRTs (21" computer displays) this way, which are
admittedly less finicky than an old tek scope, at least they never seemed
to care about orientation, and I would seatbelt them in. They were all deep
enough that the seatbelt was near its limit, so they were held in pretty
securely that way. For this, however, I will try to pick up some bungie
cords or something, to get a good strap around the seat back. I was going
to bring some larger blocks of closed cell foam to give it some cushioning
in case I had to put it in back, but I can use the same foam to wedge
against the dash in front.

I'm still a little worried about the CRT mounting in the case. I can't
seem to find the thread now (and maybe it wasn't in this group; maybe it
was in a Facebook group I also belong to) where someone had moved a
500-series scope but some part of the CRT mounting hardware had failed and
the neck had shattered. I'd really like to avoid that sort of tragedy if at
all possible.

-- Jeff Dutky