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Author Topic: SSB transmission using vacuum tubes?  (Read 649 times)
KC9KEP
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Posts: 208


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« on: December 07, 2007, 07:02:56 AM »

Hello Elmers!

I've become interested in building a SSB transmitter
with vacuum tube technology.  I've been studying
the construction projects in the 50's/60's ARRL
books and a few ARRL/QST collections on SSB transmitters.

I'd like to target about 50 - 100 Watts for 75m phone.

It seems that there are basically two popular methods
of creating a SSB exciter, i.e.  phase & filtering
systems?

The "rub" is that the required filtering components &
I.F. transformers are not as common as they once were!

Can anyone suggest a "beginner's" design for such an
endeavor, or a commercial unit that I might copy?

Here's a link of the units that I've fabricated to date:
http://www.bignick.net/Morgan_Radio/Radio.htm

Perhaps I should post my query in the Homebrewing
section, but there seems to be so much more activity
and response in the Elmer's Forums :-)

Thanks again,

--Tom Nickel KC9KEP
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N5KBP
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Posts: 293




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« Reply #1 on: December 07, 2007, 07:17:41 AM »

Look at the Heathkit early SB and HW series of rigs. The only transistors used in them was in the vfo.

Marty
N5KBP
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KA5N
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Posts: 4380




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« Reply #2 on: December 07, 2007, 07:35:22 AM »

You can get filters and crystals from IRAD in fact they sell a 9 MHz filter kit for $24 (LSB carrier crystal $12).  For IF transformers you can modify 10.7 MHz transformer out of old FM radios for use at 9 MHz.  Old (1960's mostly) handbooks and CQ's and QST's have many transmitter circuits.  You still see B&W phase shift networks for sale at swapfests and on eBay.  
I think you would have trouble duplicating a boat anchor rig.  Many parts are designed and built just for that particular transmitter.  
Good luck Allen
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WB2WIK
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Posts: 20595




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« Reply #3 on: December 07, 2007, 08:11:43 AM »

Certainly a "noble" project.  I'm sure this will me quite a bit more expensive than a modern SSB design, and unless you have a good stock of tubes, even they can be pretty pricey -- I see 7360s and such going for $25 each today, when they used to be $3.50 back when they were being commonly used.

Although "100% homebrew" is very satisfying and gives us certain bragging rights we don't have otherwise, I'd be very tempted to just pick up an old boatanchor that has the key components and is in need of restoration, and restore it, and put it on the air, and call it "half homebrew," because by that point, it will be!

WB2WIK/6
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W5RKL
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Posts: 891




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« Reply #4 on: December 07, 2007, 08:44:01 AM »


It's great that you want to build a single sideband
transmitter and for that, I applaud you!!! However,
unless you have a good grasp on vacuum tube theory
and the following topics, it's not going to be easy.
Even experienced hams have troubles building
sideband transmitters. Knowing what the following
topics do and how they work will make you task much
easier.

TOPICS:
1. Speech amplifiers
2. Carrier generators (USB, LSB, CW/TUNE)
3. Balance modulators
4. Mixers
5. VFO
6. Heterodyne oscillators
7. Drivers
8. RF amplifiers
9. Power supplies
10. ALC and biasing circuits
11. Harmonic and spurious RF radiation which includes
    RF amplifier neutralization
12. Grid Block keying ( a must for CW )

All of these topics play a role in a vacuum tube
sideband transmitter. These topics also exist in
solid state sideband transmitters but the subject
is about tube transmitters. Although your desired is a
sideband transmitter, including CW mode is rather easy
once you know how.

Which is the better, phasing or filter? In my opinion,
the filter method is the best and the easiest to
understand. I wouldn't consider phasing as that's much
more involved and not used much anymore, if at all.
You should read about it so you know what the
difference is between phasing and filtering.

As you have indicated, the handbooks of the 60/70's
present the material in such a way that they are
easier to understand instead of the Rocket Scientist
method used in current handbooks. For those who
like the modern handbooks, that's great! I simply
believe the older handbooks are much better for
new comers to learn from.

If I can be of any help, e-mail me off forum and I'll
be glad to help you.

73's
Mike
W5RKL
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WA6HDZ
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Posts: 52




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« Reply #5 on: December 07, 2007, 11:42:25 AM »

Check out ebay or your local used bookstore for 50's and 60's editions of the ARRL SSB handbook and the Don Stoner (CQ magazine) SSB book.  They have a lot of designs for homebrew SSB using basic components. Look for designs featuring common tubes especially in the modulator and PA section.  

An overlooked source for IF cans are old tube-type 2-way FM receiver strips that still show up at hamfest junkpiles.  There's also no reason why you can't wind your own IF transformers on ferrite sticks, but it is tedious!
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KE4DRN
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Posts: 3722




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« Reply #6 on: December 07, 2007, 03:54:30 PM »

hi,

Many kenwood ts-5xx and ts-8xx radios out there, most are just waiting for the next QSO.  
Some need a little TLC and others just a good cleaning.  Prices are right too.

Grab a ts-530 and you can get on the air fast,
pop off the covers and marvel at what was the
current technology !

73 james
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W8JI
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Posts: 9296


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« Reply #7 on: December 07, 2007, 07:36:04 PM »

Geeze, don't let people discourage you into buying a radio!! I didn't know much about radio when I started and I build my own receivers and transmitters from stuff I brought home from dumps. I was 12 or 13 then. That's how you actually learn.


It isn't THAT tough to build a good SSB exciter. Probably the very worse part will be the VFO and making the VFO stable, and the mechanics of the VFO.

You need an audio amp driving a balanced modulator, a filter, a few IF amplifiers and a mixer followed by a driver and PA.

I'd look at the old handbooks, or SSB for the Radio Amateur.

The old Radio Handbooks by Bill Orr had some SSB exciters. They were tube type up until about the 20th edition.

The 22nd edition seems to be all solid state, but my 20th and earlier have tube exciters.

Also the RSGB Radio Communication Handbook 5th edition is very very good.

73 Tom
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W8JI
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« Reply #8 on: December 07, 2007, 07:41:40 PM »

By the way, I'd stay away from a phasing type exciter.

I'd stick with a filter type.

Filter type exciters are actually cheaper and easier to build now. They are much less headache and cleaner.
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K9YLI
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Posts: 863




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« Reply #9 on: December 08, 2007, 08:26:39 AM »

If you want a real "cookbook" approach,  I have a heath  HW12   75 meter rig.
bought frm  AES  way back when i lived in Kenosha.
I could copy the schematic and  some of the tune up  pagers if you wanted to not design,, just copy/build.

K9yli@aol.com,
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N6AJR
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Posts: 9908




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« Reply #10 on: December 08, 2007, 09:39:22 AM »

Ten Tec also still sell kits as does elecraft, but not tube kits
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