Warning: Creating default object from empty value in /homepages/11/d132647312/htdocs/Amfone/mkportal/include/SMF/smf_out.php on line 47
Taylor Super Modulation




 
The AM Forum
November 23, 2020, 07:37:12 PM *
Welcome, Guest. Please login or register.

Login with username, password and session length
 
   Home   Help Calendar Links Staff List Gallery Login Register  
Pages: [1]   Go Down
  Print  
Author Topic: Taylor Super Modulation  (Read 13003 times)
0 Members and 1 Guest are viewing this topic.
WQ9E
Member

Offline Offline

Posts: 3225



« on: January 10, 2009, 04:03:06 PM »

I came across an early article by R E Taylor on his Taylor super modulation system.  I will scan the entire article in high res later and see if Steve wants to add it to the website.  It is a large article spread across two issues.  This is a neat looking transmitter that I have never seen pictured elsewhere.

Rodger WQ9E


* Taylor Supermodulation.jpg (1126.91 KB, 1582x2202 - viewed 908 times.)
Logged

Rodger WQ9E
flintstone mop
Contributing
Member
*
Offline Offline

Posts: 5032


« Reply #1 on: January 10, 2009, 04:09:28 PM »

I think there were some threads about the Super modulation here before. A couple of Hams used this method in the past and were not very good neighbors on the bands. Very wide signals beyond normal A.M.

The huge positive peaks it's capable of are beyond a normal reciever's capability to demodulate without excessive distortion.

125% posssibly 140% is the most that can be handled by a radio.

Fred
Logged

Fred KC4MOP
WQ9E
Member

Offline Offline

Posts: 3225



« Reply #2 on: January 10, 2009, 04:15:31 PM »

Fred,

I agree that it has the potential of being a bad neighbor.  But I think it is an interesting historical piece that will be of interest.  It is nicely constructed but fairly complex and I doubt if anyone is likely to try to duplicate it now.  But it is an interesting article.

Rodger WQ9E
Logged

Rodger WQ9E
w8khk
Member

Offline Offline

Posts: 994


This ham got his ticket the old fashioned way.


WWW
« Reply #3 on: January 10, 2009, 04:29:40 PM »

Rodger, I would be very interested in reading the entire article.  Also anything about the "upside down tube" techniques....  I have found little about this facet of AM, but used to hear the guys chat about this in the late '60s. 
Logged

Rick / W8KHK  ex WB2HKX, WB4GNR
"Both politicians and diapers need to be changed often and for the same reason.   Ronald Reagan
Steve - WB3HUZ
Guest
« Reply #4 on: January 10, 2009, 05:20:04 PM »

I have that magazine somewhere around here. Very interesting construction techniques too.
Logged
W3SLK
Member

Offline Offline

Posts: 2385

Just another member member.


« Reply #5 on: January 10, 2009, 05:40:24 PM »

Wasn't the Taylor scheme along the same lines as the Terman-Woodyard modulation? Where you have a carrier tube and a peak tube.
Logged

Mike(y)/W3SLK
Invisble airwaves crackle with life, bright antenna bristle with the energy. Emotional feedback, on timeless wavelength, bearing a gift beyond lights, almost free.... Spirit of Radio/Rush
Pete, WA2CWA
Moderator
Member

Offline Offline

Posts: 7798


CQ CQ CONTEST


WWW
« Reply #6 on: January 10, 2009, 05:45:40 PM »

The patent attached below.

Also great article in December 1950 QST for members:
"Supermodulation" - An Evaluation and Explanation

* Taylor-MODULATION-SYSTEM.pdf (392.79 KB - downloaded 458 times.)
Logged

Pete, WA2CWA - "A Cluttered Desk is a Sign of Genius"
k4kyv
Contributing Member
Don
Member

Offline Offline

Posts: 10062



« Reply #7 on: January 10, 2009, 06:10:51 PM »

The Doherty and Terman-Woodyard systems use quarter wave phasing lines arranged to achieve the impedance transformations necessary to achieve the positive peaks.  Taylor modulation is less complex, relying on extra plate voltage on the peak tube, or tapping the peak tube  down on the coil to give a step-up.

I see no reason why the Taylor system, if it were adjusted for a linear modulation modulation characteristic, would be any wider than other techniques, like screen grid modulation.  I think the wide signals were most likely a result of trying to achieve extended positive peaks, which would produce the same kind of distortion as "ultramodulation".

Doherty and Terman-Woodyard are too complicated to be practical for an amateur installation because of the difficulty in QSY'ing - unless you have one of those famous 75m rock-bound VFO's.
Logged

Don, K4KYV                                       AMI#5
Licensed since 1959 and not happy to be back on AM...    Never got off AM in the first place.

- - -
This message was typed using the DVORAK keyboard layout.
http://www.mwbrooks.com/dvorak
Mike/W8BAC
Contributing
Member
*
Offline Offline

Posts: 1042



WWW
« Reply #8 on: January 10, 2009, 07:00:34 PM »

As for style it appears to be in a similar cabinet as that used for the Hallicrafters DD1 receiver section.

http://www.radioblvd.com/DiversityDD1.html

This picture makes me drool. Talk about unobtainimum.
Logged
WBear2GCR
Member

Offline Offline

Posts: 3966


Brrrr- it's cold in the shack! Fire up the BIG RIG


WWW
« Reply #9 on: January 10, 2009, 10:41:14 PM »

Mike,

Thanks for that link... wow!!

             _-_-bear
Logged

_-_- bear WB2GCR                   http://www.bearlabs.com
w8khk
Member

Offline Offline

Posts: 994


This ham got his ticket the old fashioned way.


WWW
« Reply #10 on: January 11, 2009, 02:21:58 AM »

Rodger, I would be very interested in reading the entire article.  Also anything about the "upside down tube" techniques....  I have found little about this facet of AM, but used to hear the guys chat about this in the late '60s. 

Does anyone remember the term "upside down tube" in relation to AM?  Does this refer to the Taylor Super Modulation, Doherty, or Terman Woodyard?  Or something totally different?

I have never been successful searching for an answer to this question, but if I recall correctly, Bacon and Warren discussed this subject on 75 back in the late 60s or early 70s.  I have always been curious to know more about it.
Logged

Rick / W8KHK  ex WB2HKX, WB4GNR
"Both politicians and diapers need to be changed often and for the same reason.   Ronald Reagan
k4kyv
Contributing Member
Don
Member

Offline Offline

Posts: 10062



« Reply #11 on: January 11, 2009, 03:59:57 AM »

The Upside-Down Tube circuit is nothing more than a high level balanced modulator, with DC applied to the "carrier" tube so that there is some carrier output, but the sideband-to-carrier power can be much higher than what is required for normal 100% modulation.  The transmitted signal is DSB reduced carrier.

The original circuit was described in an article written by O.G. "Mike" Villard, W6QYT, and published in a 1948 QST.  Its purpose was not so much to allow one to pile on extra modulation, but to prevent occasional overmodulation peaks from causing splatter.  It was designed to be received on an ordinary diode detector, and the distortion is unnoticeable if the modulation level is kept close to that of normal AM.  Villard later became one of the pioneers of amateur SSB.

When the circuit is used to generate extra sideband power, the signal becomes distorted when receiving with an envelope detector, and either a synchronous detector is used, or else the BFO is turned on and the signal is received with a narrow enough bandwidth to reject one sideband and the signal is copied as SSB.  Normally, the synchronous detector is a product detector that uses a phase locked loop to cause the BFO to lock onto the original (reduced) carrier.

If the DC to the final is turned completely off, the signal output becomes double sideband suppressed carrier.  To receive the signal and  demodulate both sidebands, the reinserted carrier supplied by the BFO must be exactly on frequency and in exact phase with the original suppressed carrier.  This can be achieved using a type of synchronous detector known as the Costas Loop, which derives the reinserted carrier from the mirror-image sidebands, rather than a "pilot" carrier.

The upside down tube circuit is completely unrelated to Taylor modulation, negative peak clipping and ultramodulation.
Logged

Don, K4KYV                                       AMI#5
Licensed since 1959 and not happy to be back on AM...    Never got off AM in the first place.

- - -
This message was typed using the DVORAK keyboard layout.
http://www.mwbrooks.com/dvorak
W3SLK
Member

Offline Offline

Posts: 2385

Just another member member.


« Reply #12 on: January 11, 2009, 08:10:29 AM »

Now that I think about it, in the early days of the HN-500, I had the 'ultra-modulation in there.  It used a Pi filter in conjunction with a splatter choke. It also had 846's (?) rectifiers in the circuit. One of the caps in the chain shorted. I decided to remove the whole thing from the circuit. I'm glad I did because it sounded much better without that crap in it.
Logged

Mike(y)/W3SLK
Invisble airwaves crackle with life, bright antenna bristle with the energy. Emotional feedback, on timeless wavelength, bearing a gift beyond lights, almost free.... Spirit of Radio/Rush
w8khk
Member

Offline Offline

Posts: 994


This ham got his ticket the old fashioned way.


WWW
« Reply #13 on: January 11, 2009, 10:28:53 AM »

The original circuit was described in an article written by O.G. "Mike" Villard, W6QYT, and published in a 1948 QST

Don, I found the article in June 47 QST.  Interesting reading indeed.  Thanks for the detailed explanation.
Logged

Rick / W8KHK  ex WB2HKX, WB4GNR
"Both politicians and diapers need to be changed often and for the same reason.   Ronald Reagan
w1vtp
Member

Offline Offline

Posts: 2625



« Reply #14 on: January 11, 2009, 01:26:56 PM »

As for style it appears to be in a similar cabinet as that used for the Hallicrafters DD1 receiver section.

http://www.radioblvd.com/DiversityDD1.html

This picture makes me drool. Talk about unobtainimum.

Yep that is drool material!!  However, my Sync AM detection does a pretty good job in most cases of selective fading.  I'll drool but stay with my SDR detection system

Al
Logged
k4kyv
Contributing Member
Don
Member

Offline Offline

Posts: 10062



« Reply #15 on: January 11, 2009, 02:58:02 PM »

Now that I think about it, in the early days of the HN-500, I had the 'ultra-modulation in there.  It used a Pi filter in conjunction with a splatter choke. It also had 846's (?) rectifiers in the circuit. One of the caps in the chain shorted. I decided to remove the whole thing from the circuit. I'm glad I did because it sounded much better without that crap in it.

Those were probably 836's, high vacuum equivalents of 866's.  I tried the ultramodulation circuit for a short period in the early 70's.  It indeed did kick the  rf ammeter up with modulation, you could see the expanded positive peaks on the scope and plate current would increase with modulation, but comparative signal reports told me that the audio was just as loud without it as with it, but that it sounded more distorted with it.

The meters kick up and the modulator tube plates glow more brightly because you are generating a lot of extra audio power that is then being rectified and converted to DC, which adds to the power supply voltage causing the plate voltage to kick up with modulation.  Generating audio power and then rectifying it is an awfully inefficient and expensive way to produce DC. 

I have seen articles from the 1930's that described various schemes for applying carrier control to plate modulation (as opposed to the controlled carrier screen modulation used with the Knight T-150, DX40, DX60, and Drake rigs).  Controlled carrier plate modulation would be much more effective than ultramodulation.

One method of controlled carrier plate modulation used a saturable reactor in series with the modulator plate supply line, so that the varying class-B  modulator plate current controlled the a.c. to the primary of the final amplifier plate supply, causing the PA plate voltage to kick up with modulation.  Another circuit had the  class-B modulator wired in series with the class-C final, so that the DC plate current to the final would increase with modulation, since the modulator would act like a variable resistor in series with the final amplifier plate supply. 

Look into the pre-WW2 RADIO magazines and RADIO Handbooks for details.
Logged

Don, K4KYV                                       AMI#5
Licensed since 1959 and not happy to be back on AM...    Never got off AM in the first place.

- - -
This message was typed using the DVORAK keyboard layout.
http://www.mwbrooks.com/dvorak
flintstone mop
Contributing
Member
*
Offline Offline

Posts: 5032


« Reply #16 on: January 11, 2009, 05:04:48 PM »

Through experience gained from the use of the ultra-modulation transmitter folks might build one now and adjust it properly. But in its beginning the Ultra modulation was to purposely be as much positive peaks as possible.

During the loudness wars of the A.M broadcasters the FECES stepped in and mandated that 125% positive peaks were the limit. Some of the tube transmitters were capable of much more than 100% positive peaks. Loudness was coverage and revenue back then.

Fred
Logged

Fred KC4MOP
WQ9E
Member

Offline Offline

Posts: 3225



« Reply #17 on: January 11, 2009, 08:10:25 PM »

Well, a slight problem.  I have scanned the September part of the article but the second part appears in October of 1948 which is the only month I am missing from 1948.  There are a lot of issues on ebay but not this one.  Does anyone here have the issue by chance?

I was going to request it via inter-library loan but the electronic form requires you to fill in the page numbers which of course I do not have, Grrrr.  My wife is a professor at the library so I guess I will have to involve her in this process also when she gets back from the stores.

Rodger WQ9E
Logged

Rodger WQ9E
ka3zlr
Guest
« Reply #18 on: January 11, 2009, 08:25:21 PM »

Awesum SX-28 Notes...Kewel.... Smiley
Logged
KD6VXI
Contributing
Member
*
Online Online

Posts: 2301


Making AM GREAT Again!


« Reply #19 on: January 11, 2009, 10:18:15 PM »

Well, a slight problem.  I have scanned the September part of the article but the second part appears in October of 1948 which is the only month I am missing from 1948.  There are a lot of issues on ebay but not this one.  Does anyone here have the issue by chance?

I was going to request it via inter-library loan but the electronic form requires you to fill in the page numbers which of course I do not have, Grrrr.  My wife is a professor at the library so I guess I will have to involve her in this process also when she gets back from the stores.

Rodger WQ9E

In advance, thanks to both you and your wife.

As a youngin, I'm 'rarin' to learn about this here new fangled Aye Yemm.

--Shane
Logged
Opcom
Patrick J. / KD5OEI
Contributing
Member
*
Offline Offline

Posts: 7656



WWW
« Reply #20 on: January 11, 2009, 10:53:31 PM »

Thanks and Please, we have to see this article!
Logged

Radio Candelstein - Flagship Station of the NRK Radio Network.
WQ9E
Member

Offline Offline

Posts: 3225



« Reply #21 on: January 11, 2009, 11:08:11 PM »

In order to have AM I have to use some other "older" technology.  In order to inter-library loan an item you fill out a form on the website and it will be scanned and sent to me as a PDF file which is fine.  But to get it I have to provide the exact page numbers for the article and since the library's electronic reference does not go back that far I have to walk across campus and use the good old Reader's Guide which apparently goes back to the 1820's.

I will get part 1 of the article out in the next day or so and part 2 will be here in about 2 to 3 weeks according to the best estimate from the library.  So it will be just like when it first came out, you have to wait for next month's issue for the conclusion  Smiley

Never fear, I have also found some other great AM articles which I will scan and share.  The 1946-1954 issues in particular have a large number of great articles.  An interesting one that I doubt anybody will want to build is from 1956 and describes a 2 meter receiver preamp using a pair of 2C39A transmitting tubes in a grounded grid configuration.  The tubes each have a fan to provide the necessary forced air cooling.  I have already scanned a number of interesting low, medium, and high power AM rigs.

Rodger WQ9E
Logged

Rodger WQ9E
W5COA
Guest
« Reply #22 on: January 20, 2009, 03:32:05 PM »

Howdy All,

I read this thread with great interest, and just could not resist adding my experiences.

Back in 1960-61, I started building a HB pair of 813's push-pull link-coupled modulated by a pair of 810's. A kindly ham had given this kid a mod xfmr that was about 12" X 12" X 24". I don't think that I ever weighed it, but it was a lot of iron. I was told that it had come out of a broadcast transmitter. It had a common internal connection for the modulators and rf plate. Since it was too large to fit in one of my racks, it sat on the floor behind them.

In an old issue of QST, I believe, I read about something called negative cycle loading. I found another 3B28, hv filament xfmr, and globar resistor, and gave it a try. You hooked the resistor in series with the rectifier and placed it all across the secondary of the mod xfmr, making sure you had the rectifier oriented in the proper direction.

Having no scope, the best I could do was to get another local ham to listen for splatter as I cranked up the gain, adjusted the resistor, and then cranked the volume knob down a skosh.

I received audio reports like "my gosh, what are you running?", and "loudest audio I ever heard".

The only problems I had were blowing the resistor to smithereens one time, and arcing over my antenna insulators and setting the trees on fire.

I gave the transmitter and parts to a school prior to a move, so don't have it any more..... sigh.....

I really don't know how high the positive peaks ran, but it was a lot of fun.

73,

Jim, W5COA
Logged
flintstone mop
Contributing
Member
*
Offline Offline

Posts: 5032


« Reply #23 on: January 21, 2009, 09:32:42 AM »

It seems that using the tube rectifier in the neg cycle loading gave you better results than the silicone diodes that are typically used. I don't think any one here has had those results with super loud transmit audio without the complications and drawbacks that come from the silicone diodes/keep alive voltage,etc

Fred
Logged

Fred KC4MOP
W5COA
Guest
« Reply #24 on: January 21, 2009, 10:43:07 AM »

Howdy Flintstone,

At the time, I had a choice of using a 3B28 high vacuum rectifier or 866 mercury vapor rectifier. I chose the 3B28 for its higher PIV rating, if I remember correctly.

Keeping the filament xfmr, rectifier tube, and resistor insulated from everything else was probably the biggest challenge, since the whole mess floated at some pretty high potentials. I probably just mounted them on a wooden plank. Cheesy

73, Jim
Logged
Pages: [1]   Go Up
  Print  
 
Jump to:  

AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands
 AMfone 2001-2015
Powered by SMF 1.1.21 | SMF © 2015, Simple Machines
Page created in 0.1 seconds with 18 queries.