Archive for the ‘AM Band’ Category:

2019-05-05 Using a 7805 For An Adjustable Regulator

from FB group Building Transistor Radios Willie Barnett When you understand how the 3 terminal regulators work, you can replace the 1N4148 and the almost impossible to get 1N34 with just a pair of resistors. The 7805 or 78L05 regulator always has a fixed voltage of 5V between the O and G pins. So you

(Read More…)

2019-04-05

from FB group Vintage Transistor Radios April 6 I clicked on the link and I looked at the schematic. I’m surprised that in 1959 they had a radio that used the OTL amplifier to drive the spkr. I remember OTL was used in the early ’60s for Hi Fi amps, but I didn’t think that

(Read More…)

2019-03-31

from FB group Vintage transistor Radios April 3 Are all ‘polyvaricon’ tuning capacitors the same? They’re all about the same size. Charles Vesser Japan Industry Standard… The few that I have examined were 140 pF antenna and about 70 pF oscillator. In parallel give 210 pF. They’re probably made to match up with the loopstick

(Read More…)

2019-03-27

From FB group transistor radios Mar 29 Lin Holcomb One never knows what secrets the US government has hidden. They could have some other plans for using the WWV stations. Decades ago I worked for a radio engineer, and we had a frequency counter traceable to NBS (now NIST). He noticed that the frequency of

(Read More…)

2019-03-19 Radio Alignment Questions

From FB group Building Transistor Radios Mar 20 Bob Kirsch Any recommendation for doing a complete alignment? Documents? I used a HP sweep gen decades ago but I don’t have one now, just an old signal gen. I thought about building a sweep gen but I need to get a few parts. I have bought

(Read More…)

2019-03-11 Dipper, Wavemeter PT. 1

from FB group Building Transistor Radios Mar 11 I watched a YouTube video from Alan Yates VK2ZAY, he built a combination Dipper, wavemeter, receiver and RF generator. I built his schematic ‘right side up,’ he admitted he built it upside down with positive ground and drew the schematic, see: https://youtu.be/0pJw0m2Lz6o I didn’t attempt to build

(Read More…)

2019-02-05 Floating Detector Diodes Are Not A Good Design.

from FB group Building Transistor Radios 2019-02-05 Graeme Heal Aaron Cake has a lot of good circuits and projects. But this one uses the ‘floating detector diode’ with no DC return path, so the circuit will only work if the diode’s leakage current provides the discharge. That means the diode must be germanium, not silicon,

(Read More…)

2019-01-07 TRF Receiver Experiment

2018-01-04 also FB group Building Transistor Radios I thought that the ‘tinkerers’ who were tinkering with the loop antennas may have been getting a stronger signal because the loop antennas have a large area to capture the RF signals, so I decided to make a single channel AM Band receiver, and I chose KNX 1070

(Read More…)

2019-01-05 Substituting Chokes For A Coil In A Reflex Circuit

From FB group Building Transistor Radios 2018-01-15 Nick wants to use two 10 mH chokes close to each other in place of a coil that’s used in the typical reflex circuit. I’ll include a schematic of the circuit (from somewhere on the net). This is labeled L2. (begin my comment) Nick Bastian The coupling is

(Read More…)

2018-12-31 Zenith Royal 500 Unique Issue

Also to FB group Building Transistor Radios 2018-12-31 I have several Zenith Royal 500 radios with the ‘long range’ eighth transistor added as a RF preamplifier (chassis number begins with 8). See the attached photo. This does not require a third section on the tuning capacitor, as some ‘TRF’ radios have. Zenith added a tuned

(Read More…)

© RustyBolt.Info/wordpress
CyberChimps