Modulating a tetrode according to God

[KM1H]

Well, according to Eimac anyway

The attached is from the June 1947 CQ Magazine and is also in 1947 and later data sheets in abbreviated form.

Carl
KM1H

[N4LTA]

I saw that somewhere in a google search last week and decided that would be the way I did it on my 4-400.

Somewhere else I found the calculation for determining the actual value of the inductor based on the lowest audio frequency. If you go for 300 HZ  - the value is about 10h and if you want to go down to 80 Hz you need to get up to about 30h.

I have a 30h, 40 ma choke that I plan to mount on ceramic standoffs - it is rated 300 volts and the screen voltage when modulated will go a good bit above that. We will see what happens.

Pat
N4LTA

[N3DRB The Derb]

Carl, can you scan that as a pdf? lotsa jaggies on hi magnification.

that would be a good thing to do today - find a choke and do the socket work on the HK.

[KM1H]

I dont have that option on my scanner software and dont have a clue how to change a jpeg to a pdf.

Carl
KM1H

[N3DRB The Derb]

well, tnx for scanning it. Thats what I'm gonna do with my stuff.

[Steve - WB3HUZ]

TNX. Not the best scan but easy enough to read. What month/year is that info from?

Don't worry about PDFs. There's nothing magical about them. The problem is that you saved the scan as a JPEG. JPEGs should only be used for photographs. That's what JPEG was designed to do. JPEG sucks at image/graphic files with sharply defined edges - like text and drawings. GIF or PNG will do much better for these kinds of files and will render a much sharper image.

[KM1H]

• TNX. Not the best scan but easy enough to read. What month/year is that info from?

Were you up all night again with Tom? Wash your eyes out with an icecube   Couldnt resist!

I think this POS scanner software supports GIF, I'll retry later if it does.

Carl
KM1H

[Steve - WB3HUZ]

Yea, it was Tom's fault!   

I could read it easily. My comments were more general than to this particular scan. If you can save it as a TIFF or BMP and email it to me, I'd be happy to convert it to PDF or whatever people want here. It's good info.

[k4kyv]

The problem is that you saved the scan as a JPEG. JPEGs should only be used for photographs. That's what JPEG was designed to do. JPEG sucks at image/graphic files with sharply defined edges - like text and drawings. GIF or PNG will do much better for these kinds of files and will render a much sharper image.

I recall trying to post a graphic drawing or text on this board, and  getting an error message that it would only accept txt, doc, mp3, wav, pdf, jpg, gif, mpg and png format.  Don't recall what format I had, but it turned out that jpg was the only format my scanner would generate, that would create a small enough file in an accepted format.  I tried pdf but they always came out more than 2000 KB.

Also, some of my files have the extension .jpeg and it won't accept those.  But I made a copy of the file and renamed it .jpg and it worked OK.  I don't know for sure what the difference is between a .jpg and a .jpeg file.  I always thought they were the same thing, but apparently not.

[K5UJ]

I tried converting it to pdf on my lunch hour with Adobe 9.0

It didn't come out too well but it might be easier to print out.  I had trouble printing the jpeg file here.
The problem the the schematic.  The text is okay.  It might be possible to puzzle out the schematic with the information in the text.  I can figure out L, the reactor (whee)

Rob

[N4LTA]

To create a pdf you need the Adobe software to convert the file. A pdf file is a standard for transmitting text and photos. The advantage of a pdf is that it cannot easily be edited or manipulated. My engineering business sends pdf files created from our Autocad drawings to the end user. The files can be printed and viewed but they cannot be changed.

You can imagine the liability one might have if a critical design was submitted in a form that could be changed by someone other than the designer.

Pat
N4LTA

[Steve - WB3HUZ]

Converting it after it has already saved as a JPEG will not improve the image quality. The damage has already been done and cannot be undone. That's the thing to know when working with lossy compression schemes like JPEG and MPEG.

I tried converting it to pdf on my lunch hour with Adobe 9.0

It didn't come out too well but it might be easier to print out.  I had trouble printing the jpeg file here.
The problem the the schematic.  The text is okay.  It might be possible to puzzle out the schematic with the information in the text.  I can figure out L, the reactor (whee)

Rob

[Steve - WB3HUZ]

You do not need Adobe SW. There are quite a few SW out there other than Adobe stuff that will do it. The conversion feature is built into Mac OS. For complex docs and for not allowing editing, encryption, etc, yes the Adobe SW is probably required. But to take some text or an image and convert it to a PDF, Adobe SW is not required.

To create a pdf you need the Adobe software to convert the file. A pdf file is a standard for transmitting text and photos. The advantage of a pdf is that it cannot easily be edited or manipulated. My engineering business sends pdf files created from our Autocad drawings to the end user. The files can be printed and viewed but they cannot be changed.

You can imagine the liability one might have if a critical design was submitted in a form that could be changed by someone other than the designer.

Pat
N4LTA

[ke7trp]

Here is the way they do this with the Globe King 500C.  It works ok.  I converted it to a Dropping resistor. Audio quality really improved, Peak power of the transmitter really shot up. The scope looks much cleaner now.  The only real draw back is that you dont have the low power tune postion anymore. So you have to be carefull when tuning.

Clark

[KD6VXI]

To create a pdf you need the Adobe software to convert the file. A pdf file is a standard for transmitting text and photos. The advantage of a pdf is that it cannot easily be edited or manipulated. My engineering business sends pdf files created from our Autocad drawings to the end user. The files can be printed and viewed but they cannot be changed.

You can imagine the liability one might have if a critical design was submitted in a form that could be changed by someone other than the designer.

Pat
N4LTA

Don't kid yourself.  Even the digital sig's can be forged, this day in age.

pdf can easily be changed to a .tiff or .dwg or other format.  Shoot, I saw a ute the other day that allowed one to change a .pdf file to a .avi or .ppt!

I understand what your saying, and as someone who has done computer forensics, your liability is GREATLY minimized, as you can show prior drawings, dates, etc... And it's DAMN hard to get the file sizes back to original size after making modifications... BUT, there is nothing more secure about a .pdf file than their is a .txt file.  To wit:  My 1st wife used one of the on-line divorce paperwork generators that had a "SAMPLE" watermark across each one.  She simply used a .pdf to .txt conversion tool, dragon dictate, and had complete paperwork drawn up, for free.  The 'divorce' site thought they where 'protected' by having a SAMPLE watermark across their pages.  Yeah, right.

--Shane

[Steve - WB3HUZ]

I agree except in the case where some of the security functions of a PDF are utilized. There is no comparison here between a plain text file and a PDF file. The PDF file is quite a bit more difficult to modify.

[KD6VXI]

I agree except in the case where some of the security functions of a PDF are utilized. There is no comparison here between a plain text file and a PDF file. The PDF file is quite a bit more difficult to modify.

Except there is always printscreen and paste, as well as printing and rescanning.

As I said, thinking ANY document format is secure, is well... Misleading.

I say this as a former IT Security Consultant to Fortune 5 companies.  If you think otherwise, or think that ANY 'security function' of a .pdf will get you any type of security over anyone with more skills than your 4 yr old is... Misplaced to say the least.

IOW, if you can't control my computer, you can't control how I manipulate things on it.  Since macros are a nono on this one, I highly doubt you can control it enough to ensure that I can't Alt Prt Screen and SHFT INSRT to paint shop pro, et al.

--Shane

[w1vtp]

For the record, most scanning SW allows the user to select the DPI.  I find normal print does very well with more than 150 DPI -- 300 DPI works quite well.  I get good scans with a $50 Canon scanner by being careful with the DPI selection.  I'd love to have this article with clearer resolution. For my print photos, I use 600 DPI with very good resolution -- good enough to post - all are JPG format.

Yes, there is other SW that will convert to PDF but you have to have the data first.  I have Adobe if anyone wants to have anything converted but it can be done with several others' SW.

Totally unrelated but attached is an example of one of my photos  scanned from a 4 x 6" print - an example of picking the right DPI

Al

[KM1H]

I replaced the jpg with a png file Steve. Ive also saved on my PC as a tif and bmp. Let me know if you want both of those emailed.  All the files were scanned at 300 dpi on a HP 7130 OJ. I can scan at higher resolutions if you want. If you want to put it in the archive that is fine too, it might save some future battles on here

Carl
KM1H

[Steve - WB3HUZ]

That's not changing the file. We're not talking about copying something. But rather, changing the file. As someone who has done computer forensics, you could tell the difference between the original PDF doc and a print-screen paste mash up in seconds. No company would ever have to worry about liability issues from such crude manipulation.

I agree except in the case where some of the security functions of a PDF are utilized. There is no comparison here between a plain text file and a PDF file. The PDF file is quite a bit more difficult to modify.

Except there is always printscreen and paste, as well as printing and rescanning.

As I said, thinking ANY document format is secure, is well... Misleading.

I say this as a former IT Security Consultant to Fortune 5 companies.  If you think otherwise, or think that ANY 'security function' of a .pdf will get you any type of security over anyone with more skills than your 4 yr old is... Misplaced to say the least.

IOW, if you can't control my computer, you can't control how I manipulate things on it.  Since macros are a nono on this one, I highly doubt you can control it enough to ensure that I can't Alt Prt Screen and SHFT INSRT to paint shop pro, et al.

--Shane

[Steve - WB3HUZ]

Email the tif. 

myname at amwindow dot org


Mucho TNX.

I replaced the jpg with a png file Steve. Ive also saved on my PC as a tif and bmp. Let me know if you want both of those emailed.  All the files were scanned at 300 dpi on a HP 7130 OJ. I can scan at higher resolutions if you want. If you want to put it in the archive that is fine too, it might save some future battles on here

Carl
KM1H

[KM1H]

Just sent it.

Carl
KM1H

[VE3GZB]

What you need is a good Photoshop-like image program.

Here's one that I have on my Linux box, it's called GIMP and there's a Windoze version too.

http://www.gimp.org/windows/

It's free. It's good too! Use it and enjoy it!

[N3DRB The Derb]

Carl,

macs have this kinda stuff built in to the operating system to a degree. I sometimes forget PC users dont have that sorta thing going on.

the PNG is ok fine. 

[w1vtp]

Found this on a 4-250 datasheet.  Haven't decided which approach to use on my 813 rig. All this info is good food for the designing brain.

Al