TR Switches for Vacuum tube transmitter and receiver hook-ups

October 31, 2016

Before today’s modern transceivers,  radio amateurs used separate transmitters and receivers.  They were usually very large,  vacuum tube designs,  developed a lot of heat, and were quite a bit more sensitive to drift, filtering, hum, and adjacent channel interference.

Many amateurs continue to “work” with these designs for many reasons.  If you build a transmitter kit such as we offer on our web site, you have to figure out how to connect it to a receiver and be able to share a common antenna.

It’s really fun to connect it with a ‘modern’ tube type receiver, such as the Collins, Hallicrafters, National, Drake and others.  EF Johnson sold a automatic switching TR switch, model 250-39 which worked very well.  Do a search on the internet for more information.  There are come up  for sale occasionally; be careful – the condition of older equipment is always a concern.

Pastime projects is working on a new TR switch for use between vacuum tube type transmitters and receivers.  “New” is not the proper term, as our design will be very similar to a published design from the 1960’s.  We have a couple prototypes on the bench. We also have a rebuilt Johnson Model for reference.  Watch for introduction on our web page soon.  As always, write if you have comments.  73 Glenn W8JZI  or  pastimeprojects(at)yahoo(dot)com

Just a final thought:  These designs use a vacuum tube as a switch and switching between a low to moderate powered tube type transtmitter and a vacuum tube type receiver is automatic.  Makes for very smooth transition. This is not a mechanical relay system which requires manual switching…



August 9, 2016

Today we are offering a special on our pastime projects 6V6 MC 80 Kit. This kit includes a wound and tested
Output plug in coil tested on 80 meters in our shop. In addition, we will include a new 3.5795 crystal element assembled in a FT-243 or similar style vintage type crystal holder. These are assembled and tested here, both
on a communications monitor and in a completed 6V6MC 80 Kit. These crystals are performing well for us in the
lab here at Pastime Projects, especially using our QRP mode power supply at 200 volts. The crystals have been
tested at 350 VDC with good results, but we are not ready to warranty the crystals at this time. For a limited
time we will also offer free shipping within the US. Delivery may run a little longer depending on demand,
but we are starting to build stock in advance of orders. 73 best wishes Glenn Brown for and pastimeprojects(at)yahoo(dot)com.

How to Paint an aluminum chassis at home – the Pastime Projects Way

August 3, 2016

I have an aluminum chassis with some scratches on the surface. The usual methods of preparing the surface include sanding, etching, several methods of cleaning and final preparation of the surface using caustic materials and/or
primers and so on.
I liked the old timer radio chassis look of the 1940’s and 1950’s with the crinkled black finish. I also like the
“Radio Kit” approach of the 1960’s where the look went to cool “crinkle finish” variations in green-blue
shades of color.
For preparation I washed the chassis with warm soap and water, then wiped it dry with a very soft “bar towel”.
I made cardboard cutouts the size of the vacuum tube flanges. I purchased some double-sided tape and covered one
side of the cardboard cutouts with this tape. After trim, I located these on the metal chassis. Most of the other holes on the chassis were covered with AVERY #6733 “Color Coding Labels”. I have seen these used for pricing things at garage sales.
Many stores carry the “Rust-Oleum” Brand of spray paints. I found Rust-Oleum “Multicolored



Textured” spray paint at Walmart in 239119 Sea Green. Looks a lot like the old Radio Kit color of yesteryear. Now here is where my unprofessional thinking logic really kicked in. I figured if Momma sent her beer-drinking hubby out to paint the patio furniture, he is going to use the easiest product on the market. That way he can get back to cooking those steaks as soon as possible. Just what I needed. Very little prep, quick drying, very forgiving, and really nice
results. Just be sure you spray outdoors and away from fires and flames.
This chassis prep progress will continue. Watch for future blogs.
Just remember, I am no expert, and simple share my ideas with you. This takes time, and would appreciate it if
you share with friends, just include a little note this was first seen on Pastime Projects R3tr0rad’s Blog page,
written by Glenn Brown in August 2016. Visit and hit “Contact Us” or simply mail
pastimeprojects(at)yahoo(dot)com with your thoughts. 73 Glenn

“LookMa” Oscillator Kit available without 12K5 Tube for savings.

July 28, 2016

The price of our little 12K5 40 meter oscillator kit recently increased due to the scarcity and
price increase to us for 12K5 “space charge” tubes. The tube, of course, has long been out of
production. It has the unique property of being able to function at 12 volts dc ON THE PLATE.
Due to this very low dc power, the output power is a fraction of a watt, compared to, for instance,
a higher voltage tube such as a 6aq5 which can product 2 to 4+ watts on higher voltage DC inputs.
(Tubes are not interchangeable in the circuit. – Check your tube manual). The 12K5 tubes are advertised
on eBay as well as many other sources on the internet. Just do a search for 12K5 Tubes.
We will offer our kit for $35.00 less the tube, plus $5.00 S&H in the US.
This kit will not produce enough signal to contact other radio amateurs, but it is a learning tool,
and can be used for code practice within the shack. Very best regards Glenn W8JZI for

"LOOKMA" QRP oscillator kit returns

“LOOKMA” QRP oscillator kit returns

20 Meter Version Pastime Projects “Remember When” 6V6 Transmitter Kit Dropped

July 23, 2016

Further experiments with the 6V6 “Remember When” Pastime Projects 20 meter version of the Handbook published “Slat Board” wood chassis 40/80 meter CW Transmitter has been halted. Seems the 1940 Amateur Radio do-it-yourselves guys
knew what we had to discover ourselves. Instabilities that begin to show themselves on 80 and 40 meters become game changers on 20 meters. While the crystal seemed stable and chirp free with careful adjustment on the bench while transmitting into a dummy load, connecting to an antenna changed the situation. Even with a carefully tuned 50 ohm match, the capacitor value became sensitive to close-by variables. In our own terms, this means if my hand was
within 12 inches or so of the capacitor, resonance was lost or greatly degraded. It quit working or went off
frequency! Lesson learned. (1) Wood chassis do not shield coils and capacitors from surrounding effects. (2) Instabilities in RF circuits become worse at higher frequencies. (3) Better respect your Grandpa’s designs! They
knew what they were doing.. (4) Unless you plan to operate ten feet away from your slat board 6V6 transmitter, twenty meters on the Pastime Projects “Remember When” 6V6 Transmitter is not going to work.
Got to keep your sense of humor in this business and, for goodness sake, don’t EVER quit experimenting!

By the way, the origin of the “Remember When” name for our kit is explained on page two of our instruction manual.

Very best wishes and don’t let that soldering iron get cold! Glenn for pastimeprojects(at)yahoo(dot)com.rem kit a (2)

20 meters on the “Remember When” Pastime Projects 6v6 Transmitter Kit

July 22, 2016


We have been experimenting with a 20 meter set-up for the “Remember When” 1948 era Pastime Projects 6V6 Transmitter Kit which we have been manufacturing and selling for ten years.  On the bench it appears stable, clean, and ready to go.  We have not made on the air contacts as of today.  The information is being added to our manual.  If you own a Pastime Projects 6V6 transmitter please email us for more free information.  More changes are coming!  You are going to love our next announcements. Stay tuned!

PS  Don’t You love the vintage B&W Grid Dip Meter in the picture background?  Yes, it works!   73  dear friends —  Glenn  W8JZI Pastime Projects.


June 8, 2016

After 10 years of production our little 40 meter do it yourself code practice oscillator kit faces a price increase.  We recently looked at our costs in today’s market as compared to what we paid in 2006.  The increase is effective immediately. You will still get the same pre-wound coil, a new qrp style crystal, and the detailed instruction manual we have strived to improve over the years.  While this is considered a “transmitter” kit, we very
plainly describe its communication ability as “most likely won’t be heard next door”. You kit builders know that it’s still a thrill to follow instructions and build something yourself.

Remember When QRP 40 M transmitter

Happy Building!  73 Glenn for Pastime Projects   pastimeprojects(at)yahoo(dot)com








Pastime Projects Metal Chassis Transmitter Kit added value.

February 27, 2016

The Pastime Projects 6V6/6L6 vacuum tube HF transmitter kit has been updated with coils and instructions for 80 meter CW operation.  This is in addition to the 40 meter operation previously included.

The operation change from 40 to 80 meters requires only a change in the plug in coil and a change in the transmitting crystal.  Simple and quick.

The manual now includes the drilling and winding instructions for both frequencies.  It has been our practice to include the coil form and wire for winding the coil in the kit.  Now both coils, one for 40 and one for 80 will be included in the package.  Of course, the builder will  have to wind the coils, but that’s half the fun!

Already purchased our kit?  Just write and we will send the updated version at a no charge other than postage and handling.    73  Glenn  for

6V6 Vintage Kit as QRP Transmitter

December 22, 2015

Today we tested our “Remember When” Transmitter with 135 volts on the plate.  This was done at the request of an amateur who had recently built a power supply with 135 volts out at 50ma.  He was wondering what kind of power output could he expect from our Pastime Projects kit at this voltage.

Rather that interpret tube characteristics,  I went to the shop and set up the test.  There are some photos attached. I found that we could expect about one watt output into a 50 ohm load with 135 volts on the plate. This is definitely QRP (low power) operation!

He had experience with QRP operation, so the result was not unexpected. Our power supply kit runs about 200 volts dc and provides about 2 watts out. We recommend no more that 300 volts on our 6v6 kits.  The 6v6 will provide 10 to 14 watts output in certain classes of operation and higher levels of plate voltage.

Hope the pictures show the story.  We used a new imported 6V6 such as we sell on We used a new International Crystal made to old specifications (we also stock a few). Questions ?  contact me at pastimeprojects (at) yahoo (dot) com.  73  Glenn





Pastime Projects High Voltage Power Supplies

September 3, 2015

Pastime Projects ( manufactures amateur radio kits. Two of our most favorite are the “Remember When” slat board 6V6 kit which was featured in the 1948 (and elsewhere) ARRL Amateur Radio Handbook. This simple transmitter used a 6V6 (or 6L6) vacuum tube on a chassis made of orange crate wood. It was designed for the amateur radio operator to send CW (code) on 80 or 40 meters.
Our more recent kit uses a metal chassis and an improved oscillator kit introduced in the 1960’s Handbooks. It was more stable, easier on crystals, and oscillated on 80, 40 and other bands by switching plug-in coils. Ours uses a 50 ohm link coupled output which matches today’s antennas, antenna tuners, low pass filters, and dummy loads.
These circuits, as first published, were often accompanied by a power supply design which used a 5 volt rectifier vacuum tube. We chose to use modern solid state silicon rectifiers instead. This eliminated the need for a 5 volt winding on the transformer, and the added heat, light, current demand, vacuum tube, tube socket and so
on associated with the rectifier tube.
The result is a simpler less costly power supply for you to build and enjoy. Best regards, Glenn Brown W8JZI for