Left Coast Political Scene

  Before investing a huge time sink in building / reworking the FP-200 power supply for Project X, I wanted to assure myself that everything short of the Final Amp is working! To date most of my energy has been spent on cleanup, fixing some of the mechanical issues and in general that the receiver is more or less working. To that end the Receiver works pretty well on 40 and 20 Meters. The 80M band is a work in progress. I then looked at could Project X generate an SSB signal. That was my trip down the rabbit hole yesterday. CIO, Bal Mod and Prod Detector First question: Does it generate SSB signals? That is a hard question to answer as it depends. The CIO (Carrier Insertion Oscillator) and Balanced Modulator are textbook and no rocket science here. The Bal Mod is a Diode Ring and includes both phase and amplitude balance. The CIO at 5.173500 MHz regrettably includes no "netting" the frequency so that with crystal aging it is a crapshoot to place the carrier at just the right ...

Most but not all SSB Transceivers have RF Amplifier Stages. This stage can be troublesome as it is a high wire balancing act to provide a sufficient amount of gain but not so much that the atmospheric nose amplification is so great as to negate the gain stage. The RF Amp stage can be untuned so that it is a wideband amp and a follow-on Band-Pass Filter limits the beefed-up signal just to the band you are operating within. But most of the designs some 60 years ago used a continuously tuned RF Amp Stage. Frequently a multi-section variable cap would have one section to the VFO while another section tuned the RF Amp stage. Those with Ten Tec gear like the Triton series manually tuned the RF Amp stage with a slick named "Resonate" control. The Project X has a separate control, but it is not a slug tuned coil (Ten Tec) nor even involves a mechanical variable cap. It was a slick design back in 1965 but not so today. I have been wrestling with this circuit.  Project X RF Amp Stage D...

After putting all back together, the VFO was inoperative. But now it is working, and the fix will astound you or should I say the implementation will give you cause to say," I'll be damned!" First, we must acknowledge something about Germanium transistors, like the 2N2092, which is that it is 65 years old. These class of transistors are prone to failure especially one which has a 4th wire ground lead that is internally connected to the transistor substrate. 2N2092 and 2N2093 are Equivalent PNP Devices   L to R: Collector, Shield, Base and Emitter I asked Copilot AI "What's up with Germanium Transistors" that fail?  Common Failure Mechanisms Tin Whisker Growth Tiny conductive filaments called tin whiskers can grow inside the transistor casing, especially if the interior is tin-coated. These whiskers can cause internal shorts between the transistor terminals, leading to erratic behavior or complete failure. Internal Shorting Some vintage germanium trans...

  Finally Access to the VFO Board! In looking at the schematic and measuring voltage at the emitter we had power to the circuit but no oscillation. The 1st thought was that the Germanium transistor was bad... I pulled it only to find it tested good. Plugging it into a socket on a working homebrew rig (Plessey Circuit) it was good! Now that I had access to the components I could make other voltage measurements. I noted there was voltage on the collector BUT none at the junction of RFC and 5.6K and the .01 Cap. An ohmmeter measurement across the RFC (shocking) it was open. Ah hah, found it!  Not so fast McGee! True it was open, further checks once removed from the circuit affirmed that. But there was no visible sign of an open, it was not crisped nor any leads broken off. It was just plain open.  Seeing the choke was inaccessible, there was no probing of or any accidental damage to the choke before it died. It just stopped working. The transistor is good so no huge current ...

First a caution and a funny story. I hate the type of Manhattan construction where you use Super glue to glue the cut off copper squares to a PC Board.  Frankly Super glue and Pete are a volatile combination. Somehow every time I use the product, I get my fingers stuck together.  Yesterday I had the need to use Super glue to repair something and managed to get Super glue on my index finger. The good news is that I only got it on my finger but avoided the gluing the fingers together.  When I got the T Mobile Home Internet, they required you use the Biometric function on your Smart phone. That was pretty slick as now you can open your phone with a fingerprint. Don't you just love technology. After the Super glue event, I cannot use Biometrics to open the phone and had to enter the code. Then it hit me... the Super glue prevents the phone from reading the index finger. So, I will have to wait until the glue wears off. I was laughing that I was done in by Technology! Stupid p...

 Raspberry Sundae Our ice cream sundae is a perfect metaphor for today's blog. If you love to homebrew, then you likely have a penchant for ice cream. Afterall, who in their right mind would turn down a taste of a Raspberry Sundae. But to take a bite, does involve a calculated decision. Afterall with the average age of our ham being way above 30 then it is not a simple decision as concerns for health such as lactose intolerance, adding to an already bulging waistline, cholesterol impacts and then there is that leaking filing that rapidly responds to sugar shock on the nerve endings. When you are 16, none of these issues matter for at that age it is YL's and not ice cream that are in the PFC (Pre-Frontal Cortex) and causes sensations in other parts of the anatomy. But those factors are in the process when it comes to a radical decision such as completely removing the analog VFO from the Project X radio and replacing it with some modern digital electronics. Let us ponder some of ...