Recent content by nomadradio

This circuit board has all the switches on it. For the price, buying the individual switches and the pain of replacing them seems a lot less attractive. https://stores.goldeneagleradios.com/galaxy-lever-switch-board-with-switches-for-dx2517/ He has individual switches, too. 73

There must be a McGyver way to evesdrop on that without a 'scope. But a 'scope is the only way I know to ID that fault. This radio demostrates the value of the 30-buck fleabay transistor tester. If your time is worth anything at all, it's a good bang for the buck. 73

Two of them in parallel, best I can tell. The driven element is an unbroken full-wave loop. We used a coax switch that grounded the unused coax of a 4-element antenna built on this model. Didn't seem to affect the match on the coax in use. Never could wrap my mind around that. 73

Inside. Separate coaxes feed into the building. 73

TIP42 with any suffix letter should be an upgrade from the original. 73

Not if the 7.5 Volt zener is at the top of its 10% tolerance range. 73

I'm accustomed to just pulling out Q30, 31 and Q33 to test each. D70 and 71 can be tested in circuit. The voltage on IC5 pin 5 has to be higher than pin 6 to make the radio receive. This should put at least 8 Volts onto pin 7. If the voltage on pin 7 is too low, Q33 will partially turn on...

A surface mount power transistor? The foil surrounding the part becomes the heat sink. I have no idea how to calculate the foil area required to carry the heat away from that kind of part. 73

A comprehensive cross reference between Uniden circuit-boards numbers and the brands/models where they were used would be really cool! The XLR radios are different from all later 40-channel Cobra models. President's name became Uniden some time in the 80s. But only in the USA. I have a vague...

That diode was famously vulnerable to getting toasted by touching ground on a loosened mike socket in mobile radios with that circuit board. Even briefly touching grounded metal would pop it. We adopted the habit of lap-soldering three 1N4148 diodes in series, to replace D71. For some reason...

I would unplug the bias-test jumper, sometimes called the "mirror board" and see if the radio will receive normally. If so, shorted driver/final transistors are causing the mischief. 73

Chicken or egg. Electroluminescent (EL) panel or bad inverter. If you have a 'scope check for at least 100 Volts peak-to-peak feeding into the EL panel's flat conductor. If you have drive voltage, the EL panel has gone bad. No idea how you'll turn up one of those. If the inverter is dead, and...

Is it "catching" mechanically? Or is the power to the motor failing in one direction only? A funky limit switch sounds plausible. Found the owner's manual at BAMA. https://bama.edebris.com/manuals/wilson/wr500/ 73

Here is the other half of the lower-channel mod for the Browning Golden Eagle Mark 4A. The receiver this time. The receiver comes with two tuneable bands and one "fixed" crystal receive frequency. The crystal socket is part of the front-end circuit board. Adding a third tuneable band requires...

Cool! No ferrites on the output side. Gotta learn how to do that! But nothing about where he gets his 50 Volts. 73