Archive for the ‘AM Band’ Category:

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

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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

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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

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2018-12-09 Selectivity V. Sensitivity

from FB group Building Transistor Radios 2016 Dec 9 Jim Glover An ideal receiver would have a bandpass shaped like a square wave where the bandpass is flat with no attenuation and the attenuation is infinite outside of the passband. In the real world this isn’t possible but any receiver buyer with the money would

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2018-11-19 Depth of Loop Antenna

from FB group Building Transistor Radios 2018-11-19 I shared my loop antenna – see photo, and it is somewhat 2 dimensional. The arms are 762mm across but the depth of the windings is only about 35 mm. Compare that to the ferrite loopstick at the other extreme, it’s 10 mm diameter but 100 mm long.

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2018-11-17 Cause Of Bleedover From Radio Stations

from FB group Building Transistor Radios 2018-11-19 IMPORTANT I used to work for a guy who did radio engineering and would troubleshoot problems such as this ‘bleedover’. For convenience some radio stations colocate their transmitters near or at the same site. Because the signal strengths are very high, the two stations can cross modulate their

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2018-11-07 The 2 Transistor Boy’s Radios

from FB group Building Transistor Radios 2018 Nov 7 I bought some 10 uF, 10 volt MLCC (multilayer ceramic capacitor) capacitors, which do not have the electrolyte so they can’t dry out. They are smaller, too. If they are used for replacements, then radios might last much longer. About the only thing left to go

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2018-10-29 Early Transistor Radios And LW Band

from FB group Vintage Transistor Radios 2018-10-29 One may find that some early transistor radios, along with AM, had Long Wave band before they had SW or FM. We should keep in mind that earlier germanium junction transistors had a maximum frequency that was limited to 2 to 4 MHz. The radios could have a

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2018-10-18 Admirable Admiral Radio

from FB group Vintage Transistor Radios 2018-10-20 Was it made in the late ’50s? The transistors are early RCA types. These old time radios are about 60 years old and I am amazed and inspired to hear and see that, once the caps have been replaced, they perform as well as the day they were

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2018-08-18 Two Types Of Germaniums In Old Radios

From FB group Vintage Transistor Radios There are really only two types of germanium transistors in older radios. One is for the RF and IF stages and has low collector to base capacitance. The other is audio and can handle a few hundred milliwatts. I recently replaced the germanium audio transistors with silicon, with change

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