I have always enjoyed building and experimenting with vacuum tube radios and amplifier designs as one of my hobbies. Changing soldered parts can be frustrating to get a circuit to work. What would be nice is to have a vacuum tube solderless breadboard to test circuit designs. So… I decided to make a solderless breadboard for tubes. I explored online several vacuum tube breadboard designs and ideas. Some used pcb pressure screw connectors for wiring which is a good idea but I see a problem. This type of connector is really meant for a one time connection and running the screw in and out constantly will most likely wear out the connector fairly quickly. I looked at other types of small connectors for wiring and came to the conclusion that the old workhorse Fahnestock clip invented back in 1907 is the best wiring connector for my breadboard. Below are photos of the vacuum tube breadboard that I assembled. The breadboard consists of individual component modules mounted on 12” x 12” x ¼” thick Baltic birch plywood. For each module base I used 1/8” thick Garolite cut to 2-1/2” x 3” and 2-1/2” x 4-1/4” for different sized components. Each module is attached to the breadboard using two 6-32 x 1/2”L male thumbscrews that screw into two 6-32 x ¼”L T-nuts on 2” centers in the board. At the top of the breadboard is a Garolite strip with 12 banana jacks wired to Fahnestock clips for tube power, voltage bias, filament power and antenna connections. What’s nice is that it’s easy to shift modules around on the board for component layout. I have only made tube modules for 4, 5, 6-pin tubes thus far and I’ll be making additional modules for 7, 8 and 9-pin tubes in addition to other passive components as needed. The breadboard is only capable of handling simple 1 and 2 tube designs. I’m thinking of making a second breadboard to be used in tandem for larger circuit designs.

I’m assembling a battery eliminator with some spare parts that I have to power filament and plate voltages for home brew experimental regen radios to build. Can any forum member suggest an all around resistance value and wattage for a bleeder resistor for my circuit below?

Hi Guys, I have always wanted a wide band magnetic loop antenna for my Palstar R30A radio for SWL as I’m retired and live in a HOA community. Checking out such possible mag loop antennas like the W6LVP, ICOM, etc. I have found that they are too expensive for my budget. So….searching around the internet I came across an interesting DIY mag loop antenna that looked promising. I pretty much followed the construction except that I added a pvc ½” piece of conduit to support the loop better. I could not find the suggested flat aluminum bar for the loop but a ½” wide x 1/8” thick x 6’ long flat aluminum that can be bought at a local Lowe’s or Home Deport makes a slightly small loop diameter and works. Instead of constructing the loop pre-amp circuit, I purchased a really good loop amp board and DC power injector board from a website for about as much money if I were to buy all the parts from the authors circuit. The company will include the DC power injector board for free with the purchase of the loop pre-amp. Once I assembled the mag loop antenna, I connected it to my radio to determine if it will even work. I was surprised that I was getting many stations and I haven’t even mounted it on a pole yet! Below are snap shots of the mag antenna and the DC power box. The original mag loop article and company that makes the pre-amp and DC power injector links are below. https://www.pa1m.nl/simple-active-receive-loop/ https://casarain.com/