1937 Desktop Transmitter

[WQ9E]

If you have some 6L6 tubes left after the modulator here is a transmitter for them.

[W3GMS]

Roger,
Talk about simplicity!  Paired up with the 6L6 modulator and your all set to go.  All its missing is a coil set for 160M but that would not be hard to do. 

I remember some old timers telling me how they use to really push the metal version of the 6L6 by turning it upside down and sticking it in a bath of water.  I not sure how long they lasted that way nor do I remember how much power they ran with them.  They were cheap, so when one pop'ed it was no big deal!

Regard,
Joe, W3GMS       

[WQ9E]

Joe,

I just located a Millen Variarm VFO and I think the 6L6 transmitter and modulator would make a nice match for it even though the design is a little older than the VFO.  I will have to decide between homebrewing a receiver to make it an all homebrew 160/80/40 station or pairing one of my existing 1930's era commercial jobs with it.  I also remember hearing about immersing 6L6 tubes for better cooling.

I picked up that stack of shortwave magazines and a parts RAS receiver years ago at a club meeting in Mississippi.  My wife gave me some framed poster sized reproductions of some magazine covers and attached are my 2 favorites.

Rodger

[w1vtp]

Joe,

I just located a Millen Variarm VFO and I think the 6L6 transmitter and modulator would make a nice match for it even though the design is a little older than the VFO.  I will have to decide between homebrewing a receiver to make it an all homebrew 160/80/40 station or pairing one of my existing 1930's era commercial jobs with it.  I also remember hearing about immersing 6L6 tubes for better cooling.

I picked up that stack of shortwave magazines and a parts RAS receiver years ago at a club meeting in Mississippi.  My wife gave me some framed poster sized reproductions of some magazine covers and attached are my 2 favorites.

Rodger

Congrats Rodger.  Just keep in mind that the older one has no power transformer (connected to the line like and old AC / DC  radio) and you need to exercise caution accordingly.  If I were going to use it, I'd use an isolation transformer to help with safety.  The later one with the slide rule dial came with a power transformer.  I had one but somehow, lost it during my move back in 84. Wish I had it.

Al

[WQ9E]

Al,

Thanks, I am planning to plug it into an isolation transformer although it does use an isolated B- bus so the chassis is meant to be grounded.  I believe that is the main difference between the Millen version and the original version described by Rice in his 1941 QST article which did connect one side of the line directly to the chassis.

I bought several little Hitachi isolation transformers from Fair several years ago and I wish now I had bought more since I am down to my last two.  They are small and perfect for little AC/DC radios and similar pieces of gear.  They are set up with a slight step down ratio so 120 volts in gives you 107 out.

The Variarm is definitely one of the cooler looking pieces of vintage gear.

Rodger

[W3GMS]

Rodger,

I have a pristine Millen Variarm VFO.  Your right in that would look real classy and unique even though its a few years later than the 6L6 xmtr.  I think Millen left National around 1939.  When was the Variarm introduced?  I may have a manual for mine so if you need any document let me know and I will dig through my files.   

Homebrewing a matching period rx would be a good project which I am sure you would enjoy.  If you want to get something together fast, I would recommend a National FB-7 or an HRO Jr.  Both are classy looking rcvrs not to mention the performance of the early HRO's in particular. 

Send some pictures when you get it together. 

Regards,
Joe, W3GMS         

[K1JJ]

It's amazing how radio articles and ads in 1937 revolved around the actual circuit design, voltages and tubes used, technical reasons for this or that multiplier stage, etc.  The target market was real radio experimenters and penny-pinching hams.

Nowadays, the ads usually stay clear of the specific circuitry and focuses more on "our proprietary digital-ready LSI design" that will make you "King of the bands"  and "Dominate the competition."  Kinda like an executive summary. 

T