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"On pg 241 of Lou Franklin's book" - so what does he say about this capacitor?

This gave me something to do this morning while I drink some coffee. C154 (.047 mfd.) is a RF bypass capacitor at the emitter of TR37, which is the bias supply to the RF output final TR36. you can put anything in there from .001 to .1 mfd. or just leave it out. it is working now.

the reason resistor R128 was cut was to disable the microphone audio AMC/ALC circuit so that you can overmodulate. (on the mic on the left side version of this 148GTL radio)

I should add, do this first...... remove the "shorting board" to isolate the RF driver and output from this test. test the voltages at TP9. the 6 V or so in AM Mode, and 12 V in SSB mode.

Yes, I had this problem before. Months ago on a few of these types radios. just a "hunch" I have. sounds like maybe problem in the series amplitude modulator circuit. (Q66/Q67) SSB n FM will still work if a voltage reading is present. check the voltage at the "shorting board" TP7, 8, 9...

I was in Suriname July 4 maybe 1988 or so. city of Paranam. ? ?... at the ALCOA plant. (Aluminum Company of America) a civil war going on. Buses and cars on their sides, with bullet holes. we were at a bar. bullet holes in the walls. it was "Dutch Guiana" they spoke Dutch. I have...

I just downloaded the schematic. L14 would burn up due to high current through it. If one or more of the RF amp MOSFETS Q45/46/47 got destroyed, and a short from source to drain, this would cause this. also maybe burning up Q55 TIP36 and/or Q54 also? ? So first test at TP9 AM MOD. test...

that picture reminds me, on the JB2000 I worked on, one problem was them screws, star washers, and tube socket standoffs were not making a good contact with chassis ground. So took them all out, cleaned it up. put back together then had grounded-grid again.

Well, this website is viewed worldwide, so relatively speaking, I am down the bayou from you. On the Bayou near Thibodaux. And I am not originally from these parts of the country but been through Rayne quite a few times. Listened to KBON while out there. any progress on that board?

I replace these bad SMT transistors with good old style TO-92 devices. NPN - 2N3904, 2N2222. PNP - 2N3906. I leave long leads on them, and solder to the circuit board solder traces. Easy to bend the long leads to go in the correct place. (EBC) Hold the transistor with some tweezers, while...

Yes, a few months ago, I got one of these monsters to work. It had many hands in it. has a nice newer Dahl HV transformer. but all messed up. screwed up to the max!! found problems with the 8417 driver tube wiring. the resistor at the screen was incorrect. I took out the high/low switch...

the main radio schematic is "RCI 2950DX MOSFET" first check for the bias problem on the Q62. add that resistor is needed. on the 8 MOSFET PA board, turn the bias pots, VR2 and VR3 so the wiper is at ground, so you have zero bias voltage when first turned on. then monitor the input current...

also I found this error on the one I worked on. and the schematic confirms it, on the main circuit board. https://www.worldwidedx.com/threads/rci-2970n2-2950-irf520-bias-problem-repair.264585/

is your radio drawing high current when you key it up in SSB mode, with no audio input? is the final amp board EPAC40010A ? ? with the eight FET's ( same as in a DX 98VHP )

I worked on a 2995 several months ago. same problem. no AM TX. found transistor Q66 was good. Maybe it was replaced by the last guy, that asked me to find the problem. But I found that SMT transistor Q67 was bad. So I soldered in a big old 2N3638 from my junk box, and it has worked fine...

months ago, I was given a Cobra 148GTL "D" ( made in China version ) and told it has problems and does not work. so got it working, but in SSB mode it had frequency FMing, the "Voice Lock" was squirrely. . so a few days ago it went out completely. could not change frequency. I quickly...

funny, just drank a virgin Bloody Mary moments ago. I float some of that Cholula Hot sauce in it. first put in some pickles okra and beans. maybe mix up some Cajun seasoning in it. I also like Louisiana Hot sauce.. with the red spot.

I found this bias problem on this 2970N2 I have here. but radio is still not transmitting fully. https://www.worldwidedx.com/threads/rci-2970n2-2950-irf520-bias-problem-repair.264585/#post-794662

the EPAC40010A board the board with the 8 IRF520's shows a feed back circuit with a 2W 100 ohm resistor in series with a .01 mfd. capacitor. 4 of these. you could just solder these parts in place. CB Tricks has this diagram on the DX 98VHP page. I have worked on a 2970N2 here...

I got one of them. have melted 811 plates. popping the AC input fuses. popped some of the resistors in line with the grids. etc. (yes, I need to ground the grids directly some day!) . but a friend sent me some old Russian made 811's and it has been working great since then! . make sure...