TNT transmitter question

[N9axl]

I'm thinking about building one of these 1929 vintage transmitters. I got some 1920s QST with some designs. What I can't figure out is how the two coils are connected. It looks like they aren't physically connected, but what I've read is unclear how big to make the coils for 40 meters, how they are physically placed together, and how one connects them to a modern antenna.

It appears the signal is produced, is inducted into the antenna coil, and from there I could simply connect it with a piece of coax to a modern female coax connector.  These were originally designed for open ladder line.  Now, the other problem is finding the appropriate Sangamo capacitors, ceramic standoffs, etc which must be on payBay

[W3GMS]

Look at the December 1929 issue of QST.  A great article written by George Grammer all about the TNT.   

I have a TNT that was built back then and have attached another picture which may clarify things.  Mine is on 80M but a simple grid coil change along with a reduced turn tank coil will easily allow 40M operation.  

The two coils are not connected.  One is the tank coil and the other is the antenna link.  I use mine into a 52 ohm system.  You simply tap down on the link until you get the most power transferred.  Depending on how close the link it pushed towards the tank coil will determine the power output.  You can't get greedy with output power, since when its very tightly coupled, the signal will be pretty chirpy.  Loosely coupled, the note can be surprisingly good!  

My TNT can run about 8W output with a fairly decent note.  I use a choke input power supply and my tube in the TNT is a 210.  

You will have lots of fun building one up!

73,
Joe-W3GMS    

[K4RT]

I too have been thinking about building a 1929 xmtr & PS. I had planned to start looking for parts at  Frostfest but couldn't make it.  Karl maybe you could update this thread from time to time with your progress & photos.

Joe, thanks for posting the photos.  Nice layout.  Have you heard of anyone builing a modulator for their 1929 set?

73,
Brad

[KA2DZT]

Joe,

Nice xmtr pics.

I once sent a friend a complete set of parts to build one of those xmtrs.  He asked me for a 500pfd Cardwell cap from that period.  I sent him the whole kit including those old brown caps exactly like the type in your set.  I sent all the power supply parts including meters.  I tested the brown mica caps and to my surprise they were still good.

Shortly after I sent the parts, WA3YNW Bill posted pics of the completed xmtr.  It was nice to see some of the tens of thousands of parts I have pressed back into service.

Looked at all the Frost Fest pics, nice of you to gift that last S-53 receiver.  Sometimes it's not about the money, it's worth more just to let someone else enjoy some of this stuff that we all have collected over the years.

Fred

[VE3LYX]

I have many 29 transmitters I use. First was a TNT. The coil is as mentioned inductively coupled. That is just one way of mounting it. I prefer the link loop over the centre. Coils are wound on  rattle paint can (to form them)with 1/4 to 3/8 inch copper tubing. 7 mhz 7 turns will work with a good big vintage tuning cap. 9 turns will probably put you more in the window but with a TNT your grid coil has to match your tuning range. Measure with a GDO and make sure it is with the tube you are using installed in its socket.
An afternoon will build one. I have a 45 TNT, a 211Hartley, A 01A Tuned grid tuned plate, A 01A hartley, , A rat trap hartley 45 tube, A Mopa , (twin 01As,) and a modulated 0171A modulated by a 01A(series cathode) Plus a handful of experimental s .My 45 TNT is also phone capable and I have worked at least two members of this list with it at several hundred miles away.
Lots and lots of fun. I try to participate in AWA events and run each rig that fits that weekend at least for one contact.
Interest in these was fostered by Lou VE3AWA. It has completely revived my interest in Ham radio. Be careful. It is addictive. ;>) You also need a regen to really "get it" and Nostalgia light bulbs hanging in your vintage shack. What will amaze you is how well it all works. As good as anything you currently have if you do it well.
donVe3LYX

[W3GMS]

Joe,
Nice xmtr pics.
I once sent a friend a complete set of parts to build one of those xmtrs.  He asked me for a 500pfd Cardwell cap from that period.  I sent him the whole kit including those old brown caps exactly like the type in your set.  I sent all the power supply parts including meters.  I tested the brown mica caps and to my surprise they were still good.
Shortly after I sent the parts, WA3YNW Bill posted pics of the completed xmtr.  It was nice to see some of the tens of thousands of parts I have pressed back into service.
Looked at all the Frost Fest pics, nice of you to gift that last S-53 receiver.  Sometimes it's not about the money, it's worth more just to let someone else enjoy some of this stuff that we all have collected over the years.
Fred

Hi Fred,
Good for you sharing those parts.  Everyone needs to do more of that in my opinion.  Speaking of Bill-WA3YNW, I am talking to him on the AWA net on 3.837.  He is a good guy for sure and I just sent him some antenna insulators from the late 20's.  Martha and I had a nice visit with him at his QTH a few years back. 

Your right, its about more than the money.  The smile on his face was well worth it. 

73,
Joe-GMS

[W3GMS]

I too have been thinking about building a 1929 xmtr & PS. I had planned to start looking for parts at  Frostfest but couldn't make it.  Karl maybe you could update this thread from time to time with your progress & photos.
Joe, thanks for posting the photos.  Nice layout.  Have you heard of anyone builing a modulator for their 1929 set?
73,
Brad

Build one!  Parts are out there and I know you will enjoy building a TNT or Hartley is lots of fun.  My next breadboard project is a 40M Hartley. 

Bob-W2ZM built a Harley and he modulated it with a Heising modulator.  He even used an old fashion Candle Stick Microphone.    As long as he kept the the modulation percentage around 70 % he had very little FM'ing.  So yes, it definitely can be done. 

Joe-GMS

[N9axl]

Thanks. I grabbed this article and it gives very clear and detailed descriptions of what to do -- including the spacing for a 40 meter coil - 3/16 of an inch. I would do 80 but I don't have an antenna at present for that band.  Now, I can get my hands on a UV200 and the base. The UV200 is a detector tube so no go I think but the base seems the same. 


There are many blessings in my job -- which is being a university library director -- and one of the perks is I can go downstairs where we have a complete bound run of QST and move volumes as needed to my office.  That makes these projects so much easier.

[KA0HCP]

Here is my TNT, type 45's in push-pull.

[N9axl]

Very cool.  I will get on with this project in the next week or so.  I think starting with making the coils and the base.  I will have to search out the parts but I believe I've found a supplier who can provide me all requirements in a single order. 

[W3GMS]

Here is my TNT, type 45's in push-pull.

Very nicely done PP 45's in a TNT configuration!

Joe 

[VE3LYX]

My most favourite Hartley 211. Used for all 40m work in the last Linc Cundall Event.
donVe3LYX

[PA0NVD]

I made one for AM, but with a crystal in a replica holder. The crystal lies on a plate and a small metal plate simply lies on top connected with a small wire. The transmitter is a little more complex, oscillator, buffer, PA and grid modulator. Output approx 6 Watts AM
The crystal holder is in the third photo
Oscillator- PM4DX, buffer- PP430, PA-PX4, modulator-PM4DX.
Antenna coupling by selection of taps at the PA coil, PA neutralized.
All parts except the crystal holder, the chassis and the coils are original. The antenna current meter is a 192x hot wire meter.
As you say Don, real fun to operate the transmitters. I also made an amplifier with a VT17 for it. Gives 40 Watts AM

[VE3LYX]

I really like that rig. You did a wonderful job!
donVE3LYX

[Chris P.]

Karl,

How are things coming along with the TNT?

Here is a video of my TNT in QSO with Joe on his TNT during the 1929 BK. Hope to hear you join in on the fun next year!

https://www.youtube.com/watch?v=tEmfygHnQ3I

[N9axl]

I'm ordering parts right now.  It will be a few weeks. I made one of the coils using 8 feet of  1/4 copper tubing. At 3 inches long, 2 3/8 diameter and 6 coils I computed this to be 1.2 micro-Henrys. My coil seems relatively uniform in shape with about 1/4 inch between turns.

Now the other coils obviously needs to be be longer. I thinking in the 5 to 6 microhenry range.  How precise does the manufacture have to be? 16 turns at this diameter 6 inches long makes 5mh.

I read all these complicated ways people make these coils. I ended up just bending it around an antique can of Comet bleach powder which, incidentally, happens to be exactly 2 3/8 inches in diameter.  I suspect I've rediscovered an authentic 1920s ham radio fabrication technique. Hi.

[VE3LYX]

There is some TNT and a hartley being tested today with various types of modulation. 3605kcs + if necessary. Hartley at top of each hour and the TNTs tonite between 7 and 8 pm. Feel free to listen in.

donVe3LYX

[N9axl]

I will see. I just checked and was getting s9 plus 20 noise across all of 80 meters. This is not normal and perhaps it will subside.  20 seemed to be hopping.  I was using my HQ-170C. I'll check again later and try a different receiver.

[VE3AWA]

Hello,

If you are interested in building an early transmitter I invite you to check out: https://groups.io/g/AWAGroup

The AWAGroup focus is on the building, restoration and use of Ham Radio transmitters and receivers common to the era 1896 -1941.

Along with 138 kindred members you will, after joining, find information on 1920s rigs and receivers in the Files section. For rig info specifically go here: https://groups.io/g/AWAGroup/files/1.%20Transmitter%20Articles

73, Lou VE3AWA

[W7TFO]

If any of you OM's get stuck for vintage parts, hit me up.

I have more than I'll ever use, and might have what you need.

73DG

[Opcom]

Some day i would like to visit your bunker of doom.

[WU2D]

This is my 160 station for the 1929 Contest. It is a simple 211 Hartley and a pair of 27's in a Regen. 

[VE3AWA]

Hello,

Here it my latest restoration, a Radio Engineering Laboratories (REL) Cat. Nr. 175-TNT (ca. 1930) ham transmitter with a RCA UX-210. 

It works...after their fashion.

73, Lou  VE3AWA

[W7TFO]

That is a pretty design with a great restoration.

73DG

[VE3AWA]

Thank you, Dennis.

Here is the "before".

73, Lou

https://groups.io/g/AWAGroup