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Post by Deleted on Mar 28, 2017 19:28:13 GMT -5
My childhood dream radio from the early 1980's. Been searching for a while as they were overpriced. Got one that is 8.5 to 9 out of 10 condition.
Of course, there is no service info on it. No SAMS. No nothing. LOL
Anyone know the sister radio for this?
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Sandbagger
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Post by Sandbagger on Mar 28, 2017 21:11:47 GMT -5
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Post by Deleted on Mar 28, 2017 21:16:04 GMT -5
I was looking for full blown procedure. I will open it up and verify the PLL. |
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Post by Deleted on May 15, 2017 19:07:38 GMT -5
I was looking for full blown procedure. I will open it up and verify the PLL. OK. So I went over this radio with that schematic. The power supply is same as the schematic, but the main PCB is different animal. The PLL is not a 7131. It is a UPD2814C. The modulation circuit is not the same as the schematic, either. Mine only has one 4558 op amp chip. The schematic has 2. It appears they put an entirely different PCB than in the schematic. If anyone has any other info, it would be greatly appreciated. |
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Sandbagger
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Post by Sandbagger on May 16, 2017 6:25:50 GMT -5
I was looking for full blown procedure. I will open it up and verify the PLL. OK. So I went over this radio with that schematic. The power supply is same as the schematic, but the main PCB is different animal. The PLL is not a 7131. It is a UPD2814C. The modulation circuit is not the same as the schematic, either. Mine only has one 4558 op amp chip. The schematic has 2. It appears they put an entirely different PCB than in the schematic. If anyone has any other info, it would be greatly appreciated. It's odd that Radio Shack would put two different circuit boards in the same model radio. Usually when there's a change, they release a completely new model. Similar to what they did with the TRC-458 > TRC-490, and TRC-450 > 451. It's possible that the schematic you found is for the wrong radio. |
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Post by 2600 on May 16, 2017 23:15:36 GMT -5
At least GE would put a suffix letter behind the model number when they changed vendors. Apparently RatShack didn't feel obligated. The board with the 7131 most certainly came from a different contractor than the one with the uPD2814. That board is most likely made by Uniden. They would typically identify the main circuit board with "PB" followed by some digits. Might be etched into the copper, or printed in the white screen-print ink on the component side. That number will almost certainly be used in more than one other radio. Uniden would use the same board for multiple contracts, radios they sold to different brand names. Good chance that board is documented in some other brand/model. The control wiring and installed options may be different if it was used in a mobile radio, for example.
73
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Post by Deleted on Jul 15, 2017 9:39:29 GMT -5
Nomad,
On the solder side of the PCB, is P-200820. That is the only number I could find.
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Sandbagger
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Post by Sandbagger on Jul 15, 2017 10:39:28 GMT -5
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Post by mark4 on Sept 26, 2017 20:45:42 GMT -5
I was looking for full blown procedure. I will open it up and verify the PLL. Just trying to clarify. The TRC-441 has only one op amp also. 4558. The schematic shows 2 sections of one 4558 op amp. There were 2 TRC-432's made. The second one was designated TRC-432 on the catalogue number on the box. |
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Post by mark4 on Oct 3, 2017 17:52:36 GMT -5
I have the one with the LC7131 PLL. Tried hooking up a D104 Silver Eagle Plus and it just pulsed and squealed. But it's ok with the stock mic. I know it needs re-capping. 20db pad on gain CCW nothing would help it. Any ideas? I use the same mic on my TRC-440. And what is the best way to open this up to 100% modulation? All kinds of info online clip Q10, clip Q12, clip R56. I don't like clipping the limiter usually changing a value to achieve 100%. |
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Post by Deleted on Jan 2, 2018 21:05:52 GMT -5
Does anyone have a President Old Hickory schematic? This radio has the same PLL and seems to have the same front panel controls. Not available on the net. I would gladly buy it if it is the right one. If no schematic, component layout pic would help.
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