Posts Tagged ‘coil’

Pastime Projects rights to copy

July 10, 2018

The Pastime Projects (www.pastimeprojects.com) web site contains warnings about copyright
terms and conditions. This may frighten away those experimenters who are inspired by the
vintage makeup of our kits. That is the last thing we want to do! Please email us at
pastimeprojects(at)yahoo(dot)com for permission to copy or request copies of our materials.
We are “Makers” “do it yourselfers” handy men, or what ever you call yourself!
Let us hear from you! How can we help you?

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What is next at Pastime Projects?

July 5, 2015

Got an email from one of our customers wondering why we didn’t make the output on our 6V6/6L6
transmitter kit a pi-network instead of link output. Very good question! Probably one factor
in our decision was the cost of the change. Variable capacitors are expensive. The chassis size
would probably have to be larger also. But, these are not big issues. He is probably right; we
should revisit the pi-output design.
Some of the projects underway now include:
1. Regenerative receiver with tube(s) and toroid coils – Short Wave design with capability
to tune ham radio cw, am, and ssb in a rudimentary fashion. Status at this time is a prototype
6 – 10 MHz model that is very promising. Needs to be simplified for easy duplication as a kit.
Current model runs on 12 volts dc. No project completion date set.
2. Our low pass filter design converted to PCB configuration. We have the tools but not
the talent or time to complete this task. Interested in volunteering your expertise in this
very basic board design?
3. Vacuum Tube T-R switch based on vintage Handbook designs for handling our transmitter/
receiver interconnection automatically transferring from transmit to receive mode. Well underway
with this project.
4. Simple receiver design, probably solid state, to allow reception of cw along with our
transmitters..

Any ideas or suggestions? Let me know. Glenn W8JZI(at)ARRL(dot)NET or go to contact us
page of http://www.pastimeprojects.com7.28.09 prod

Pastime Projects Vintage style 6V6 Tube Type CW Transmitter – Another reveiw.

February 8, 2014

We would like to thank Amateur Radio Operator WB0FDJ Clarence for his writeup in eHamNet of our slat board
vintage style 6V6 CW 80/40 meter CW kit. See http://www.eham.net/reviews/detail/10299. It is reviews like
this that bring others to our web page http://www.pastimeprojects.com . Thanks Clarence and happy operating!
Glenn pastimeproject(at)yahoo.com

Plug-in Coil forms for the Radio Builder

April 30, 2012

“Back in the days” home built radio receivers and transmitters often used plug in coils. Plug in coils were used with variable capacitors to create an “L-C” circuit (L being the inductance and C being the capacitance).  The coil-capacitor combination was connected in parallel to tune the cicuit. To narrow the range even further a second variable capacitor would be wired in parallel with the LC circuit.  This  second variable would be of low value and would change the resonant frequency of the circuit a very small amount. It would, in effect be the “Band Spread” of the tuning circuit. One more obvious example was the wonderful old Hallicrafters Recievers. They had the main tuning dial on the left, and a bandspread dial on the right.

Radio amateurs are interested in very small portions of the radio spectrum. These small frequency allocations were best tuned so that the whole CW or Speech portion of the Amateur band would cover the entire swing of the variable tuning capacitor.  By narowing the coverage,  hams could spread out the signals.  While many receivers used a complex switch to change frequencies.  The plug in coil was simpler, less costly, and a favorite amoung our predecessors.

Pastime Projects (www.pastimeprojects.com) introduced new plug in coil forms in October of 2010.  The dimensions and construction of our coils is shown in the attached sketch.

The Pastme Projects coil form is available either glued or unglued. The joint is edge glued between the coil form and the octal base. The glue used in the factory is Loctite Stik n’ Seal Non-Toxic adhesive manufactured by Henkel Corp of Avon Ohio  www.loctiteproducts.com

While the coil form of old may have used 4 pin or 5 pin sockets, these have become scarce.  The use of the octal base makes more sense and give us some choices in the amout of taps and/or coils we can combine on one form.  An obvious disadvantage of the octal socket is more friction in inserting or removing the coil from the base.  We have found that the extra unused pins can be carefully cut off.  We have easily removed every other pin and ended up with a 4 pin socket which is much easier to work with.  It still allows the allignment of the coil into the correct pins in the base because of the keyed center pin on octal bases.  You can choose how many pins you need on your coil for your project. 

 

Why not include plug in coil forms in your next project?  Vry 73 es bcnu Glenn for Pastime Projects.