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A CORRECTION
I gave the wrong links for the "Radiotron Designer's Handbook". I gave links to the table of contents only, the full text is available, it is:

Radiotron 4th Edition:
<>

Radiotron 3rd Edition:
<>

Sorry for this, I didn't notice until I reveiwed my post later.

On 12/30/2024 9:12 PM, Richard Knoppow via groups.io wrote:> wave response. Beside scope specs also see the catalogs for probe specs.

--
Richard Knoppow
Los Angeles
WB6KBL
SKCC 19998

Anita Abranovic <anita.abranovic@...> added the photo album JFETs substitution for 12au6s in 575 curve tracer ( /g/TekScopes/album?id=299769 ) : Both horizontal and vertical amplifiers have these instead of matching 12au6s

In very good mechanical condition, lights up when plugged in, controls and buttons seem to work.
$100 and I'll ship free (from Austin) CONUS only please.
I can't guarantee it since I don't have any probes / scopes that are compatible as far as I can tell.
Email if you want a picture.
Thanks!

A few things to consider when selecting probes:

Check the probe's compensation range against the input capacitance of the scope input.

For work in tube circuits check the max input voltage spec of the probe. Also consider how safe the probe is for high voltage circuits.

Lastly consider the attenuation of the probe against the v/dev range of the scope against the voltages in the circuits you're working on.

The Tek P6006, P6008, P6009 should be considered. The first two are 10x. The latter is 100x.

Mark,
I listed the Multiplier and knob on eBay.

Barry

Hi Joel,

Sorry to say, they are already spoken for. I will let you know if that changes.

Regards,

Barry

Hi Barry,
I'd be interested in buying the remaining V/Div knob(s). The ones I have have lost the silkscreened numbers (1/2/5/10 V etc...). Will pay a reasonable price + shipping to France, of course.
Sincerely,
Joel Setton

I just got an email from groups.io saying Dennis is due to be billed for
this.



1. Is Dennis still with us?

a. If no, groups.io need to be informed who should be billed
b. If yes, and he's not able to handle this, as above.



Cheers, David

I don't know of a reason to call the 535 best for audio work, but if so, I'd pair it with a 1A7 plug in for it's 10 uV/div sensitivity and variable bandwidth, 2nd choice 1A1 for 5 mV sensitivity with the two channels chained.? Haven't used a 500 series scope since the early1970's. For audio, I would much prefer the 5000 series scopes for solid state, large screen, and with a 5A22 plug in, the same 10 uV and variable bandwidth. 7000 series with 7A22 plug in also good. Of course this topic could be argued endlessly.

John?? KK6IL

Thank you, John, Dave, and Richard!? Now that I think about it, I did see that P6006 probe mentioned on eevblog, IIRC.
Much appreciated!
Jim

I’ve been using the WBT solder on all my Tek repairs and have had zero issues. But I bought my 1/2lb when it was $50 cheaper. And still have over half of it left.

Hi Jim. Always glad to encounter someone using tube scopes in this day and age. I design and troubleshoot with tube scopes as well, although I often reach for the 2465A. Now it would be hard to find a Tek scope that could not be used for audio work. My personal preference is for the 502 or 504. The 504 is cheap, nice and portable, and offers adequate bandwidth. There is no fan so they are very quiet. On the downside they of course are single channel. The two channels of the CA are often very useful. The 530 series, the 531 and 535 both are good scopes for low frequency work, having a 15 MHZ bandwidth. However they do constitute a lot of scope for the application. They are big, heavy to move around, and noisy. They both are fairly complex, especially the 535 with delayed sweep, which I did not find very useful but it is there if you need it. It is tricky to find one that doesn’t have its problems, especially considering the age. If something goes wrong fixing a problem can be tricky. Also getting one shipped without damage can be a challenge. But with say a CA plugin they are a fine instrument. They originally came with a 6006 10X probe, which I use with most of my scopes. I have a lot of parts for these scopes, so if you do get one let me know if you need something. Best regards.

The handbook for the scope should tell you its input impedance which will tell you what probes it can use. Typical scopes have 1 megohm input but not all. Probes can provide voltage range extension which is accompianed with increased impedance, i.e. a 10X probe will give you 10 meg impedance. Probes usually also have some means of compensating for capacitance, usually an adjustment on the probe to optimise its square wave response. Beside scope specs also see the catalogs for probe specs.
Now, if you are going to explore vacuum tube amplifiers you absolutely need the "Radiotron Designer's Handbook" 4th edition. Available several places on the web for example:
<>
Books on this site are very well scanned and complete. They are free.
Actual hard copies are still available, do a web search. Personally, being quite old fashioned I prefer hard copy actual books but must settle for electronic versions where the originals are not available or are too expensive.
Earlier editions of the Radiotron are of historical and some practical insterest, the 3rd edition is available at the same site:
<>
There will never be another book like the 4th edition, an excellent compilation of audio design at about the end of the vacuum tube period.
BTW, I also have the original Australian edition (in hard copy) and the American edition has everything and is excellently reproduced so there is no advantage to searching out an original.
I bought a 4th when they first came out and wore it out. I have since gotten two used ones beside the PDF version.
Lots of other tube audio books at Tubebooks.org
I wonder why the Tek 535A is considered so good for audio?

--
Richard Knoppow
Los Angeles
WB6KBL
SKCC 19998

Jim
The Tek catalog from March 1967 is what you need. I've had one for years and its one of the best single references for the 500 series stuff that you will find. I see its available on Tekwiki - lots of data on appropriate probes and plugins.
DaveB, NZ

Hi, everybody.
So at some point I will take the plunge into vacuum tube audio, and according to George Lydeck on this group, the Tek 535A is the best scope ever for tube audio work.? Now, I figured out that the letter series and 1- series plug-ins, although not all of them, are the ones to plug into this mainframe.? I have that stuff on my Test Equipment Wishlist already.
OTOH, plugging directly into scope or plug-in inputs (assumed BNC, since I don't really want to go down the rabbit hole of UHF connectors) is probably not going to be productive, so I will need some probes.? Type N, SMA, 3.5 mm, BNC, and TNC are quite enough variety in my garage lab, thank you very much.

Try as I might, on TekWiki and the Internet at large, I cannot find anything specifically saying which Tek probes are appropriate for a vacuum tube scope such as the 535A.? Maybe this is tribal knowledge?? AFAIK, I have not used a scope with more than 1 tube, the CRT, (I was born in 1965, approaching 60 years old early in 2025), so the world was mostly solid-state by the time I was old enough to be playing around with scopes.? Come to think of it, all 5 of my current scopes have CRTs, and I don't think I've owned one yet with an LCD screen.? I'm in the 'tween generation, I guess.
Any recommendations for probes for a 535A?? Plug-ins also would be a good idea to know for the wishlist.
Thanks a bunch!
Jim FordLaguna Hills, California, USA

For AudioPhools, it also MUST contain micro ground meteorite powder gathered in the dark of the moon? by stygian witches. :)

????? Bruce Gentry, KA2IVY

Never could find a product specification PDF... "Halogen free flux"
is about all.

I can say I have used it on assorted Tektronix ceramic strips,
successfully. (Re a 575 mostly, few other odds and ends here and
there.)

I'm in Dayton, Ohio, and Parts-Express is local to me.

I squigged the parts in where I could, and used very little silver
solder, and so I still have most of the 1/8 lb roll I bought some time
ago.

On Mon, Dec 30, 2024 at 7:57?PM Shirley Dulcey KE1L via groups.io
<mark@...> wrote:

Nice to know it exists. I wouldn't have thought to look for audiophile
solder! I wonder what else is in it?

On Mon, Dec 30, 2024 at 7:36?PM David Holland via groups.io
<david.w.holland@...> wrote:

I give you ... not 2%... not 3%... but 4!%, yes four whole percent!.. :-)



And if you don't like Amazon:



(don't read the PE product text too closely, as the audio-phoolery may
cause brain damage.)

That said, AFAIK, WBT is still producing it:


Its leaded too. WBT makes a WBT-0805 that's lead free....

(Not cheap tho....)

David

On Mon, Dec 30, 2024 at 7:13?PM Shirley Dulcey KE1L via groups.io
<mark@...> wrote:

The problem is that tin-lead-silver alloys with 3% or more silver is
unobtanium now; nobody makes them any more, likely because of limited
demand caused by the cost of silver. If you want it you'll have to track
down old stock. Tek may recommend 3% or more silver, but surely 2% is
better than 0%.

Lead free solder with 3% silver is readily available; the SAC305 alloy

that

is the most popular lead-free solder fills the bill for that. I'm fond of
the Special Blend solder that Sparkfun sells, with a small amount of
antimony added; it flows a bit better than standard SAC305. But most
lead-free solders have a higher melting point than 63/37 or 62/36/2
(bismuth alloys are the notable exception), so you'll have to work more
carefully with them.

On Mon, Dec 30, 2024 at 6:50?PM Dale H. Cook via groups.io

<bridgewaterma=

[email protected]> wrote:

On 30 Dec 2024 11:15 am, Shirley Dulcey KE1L wrote:

If you would prefer the ease of use of tin/lead/silver solder, you

should

look for Sn62Pb36Ag2 solder.

I am using a similar mix but with 3% Ag, because the Tek service

manuals

specify a minimum of 3% Ag for use on the ceramic terminal strips.
--
Dale H. Cook, GR/HP/Tek Collector, Roanoke/Lynchburg, VA

Nice to know it exists. I wouldn't have thought to look for audiophile
solder! I wonder what else is in it?

On Mon, Dec 30, 2024 at 7:36?PM David Holland via groups.io
<david.w.holland@...> wrote:

I give you ... not 2%... not 3%... but 4!%, yes four whole percent!.. :-)



And if you don't like Amazon:



(don't read the PE product text too closely, as the audio-phoolery may
cause brain damage.)

That said, AFAIK, WBT is still producing it:


Its leaded too. WBT makes a WBT-0805 that's lead free....

(Not cheap tho....)

David

On Mon, Dec 30, 2024 at 7:13?PM Shirley Dulcey KE1L via groups.io
<mark@...> wrote:

The problem is that tin-lead-silver alloys with 3% or more silver is
unobtanium now; nobody makes them any more, likely because of limited
demand caused by the cost of silver. If you want it you'll have to track
down old stock. Tek may recommend 3% or more silver, but surely 2% is
better than 0%.

Lead free solder with 3% silver is readily available; the SAC305 alloy

that

is the most popular lead-free solder fills the bill for that. I'm fond of
the Special Blend solder that Sparkfun sells, with a small amount of
antimony added; it flows a bit better than standard SAC305. But most
lead-free solders have a higher melting point than 63/37 or 62/36/2
(bismuth alloys are the notable exception), so you'll have to work more
carefully with them.

On Mon, Dec 30, 2024 at 6:50?PM Dale H. Cook via groups.io

<bridgewaterma=

[email protected]> wrote:

On 30 Dec 2024 11:15 am, Shirley Dulcey KE1L wrote:

If you would prefer the ease of use of tin/lead/silver solder, you

should

look for Sn62Pb36Ag2 solder.

I am using a similar mix but with 3% Ag, because the Tek service

manuals

specify a minimum of 3% Ag for use on the ceramic terminal strips.
--
Dale H. Cook, GR/HP/Tek Collector, Roanoke/Lynchburg, VA

I give you ... not 2%... not 3%... but 4!%, yes four whole percent!.. :-)



And if you don't like Amazon:


(don't read the PE product text too closely, as the audio-phoolery may
cause brain damage.)

That said, AFAIK, WBT is still producing it:


Its leaded too. WBT makes a WBT-0805 that's lead free....

(Not cheap tho....)

David

On Mon, Dec 30, 2024 at 7:13?PM Shirley Dulcey KE1L via groups.io
<mark@...> wrote:

The problem is that tin-lead-silver alloys with 3% or more silver is
unobtanium now; nobody makes them any more, likely because of limited
demand caused by the cost of silver. If you want it you'll have to track
down old stock. Tek may recommend 3% or more silver, but surely 2% is
better than 0%.

Lead free solder with 3% silver is readily available; the SAC305 alloy that
is the most popular lead-free solder fills the bill for that. I'm fond of
the Special Blend solder that Sparkfun sells, with a small amount of
antimony added; it flows a bit better than standard SAC305. But most
lead-free solders have a higher melting point than 63/37 or 62/36/2
(bismuth alloys are the notable exception), so you'll have to work more
carefully with them.

On Mon, Dec 30, 2024 at 6:50?PM Dale H. Cook via groups.io <bridgewaterma=
[email protected]> wrote:

On 30 Dec 2024 11:15 am, Shirley Dulcey KE1L wrote:

If you would prefer the ease of use of tin/lead/silver solder, you should
look for Sn62Pb36Ag2 solder.

I am using a similar mix but with 3% Ag, because the Tek service manuals
specify a minimum of 3% Ag for use on the ceramic terminal strips.
--
Dale H. Cook, GR/HP/Tek Collector, Roanoke/Lynchburg, VA