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Message |
    
Snapperhead
Intermediate Member
Username: Snapperhead
Post Number: 206
Registered: 2-2002
| | Posted on Sunday, April 17, 2005 - 6:25 pm: | 
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Hey all, I got a Redco Digi-Scan that I want to wire up to my old style Cobra 148gtl. I'm not sure what model digiscan it is. On back it sais model UFO. There's no RDS-1 2 etc...Really strange.....I have another DigiScan laying around that's wired up to a old grant, but It has the rainbow ribbon on back model No. RDS-1.
This digiscan is rather larger than the RDS-1....It has a red wire wich wires to power switch and black wich wires to ground......But I have two miniture coaxes that I need to know where to wire two......I think the shields on two coaxes go to ground like on the can of L23...I was told that MB8719 chip has to be removed. Is this true.......Any input from you techs or someone who is familiar wireing up these bootleg devices would be appreciated.... |
Snapperhead
Intermediate Member
Username: Snapperhead
Post Number: 208
Registered: 2-2002
| | Posted on Sunday, April 17, 2005 - 8:38 pm: |
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Hey Racer X thanks for URL. It does seem similiar to my UFO. There is a coax #1 and a second #2 that are marked on my wires. Now a few more questions. On this procedure
Step #4: Locate 8207 and cut one lead. What component is 8207, schematics is very hard to see. Also, on this step, Step 11: Remove C891C70 to prevent down mixer oscillation. Is that two seperate Caps?.....Just making sure, before I give it the attempt.....Thanks again, Racer X
73's ~:^D)> |
Racer_x
Intermediate Member
Username: Racer_x
Post Number: 332
Registered: 2-2005
| | Posted on Sunday, April 17, 2005 - 10:01 pm: |
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I think it's a typo and should be R207. If you look further down the instructions there are specific points shown in a picture, and R207 is one of them. Also, step #4 in INSTALLATION #1 references cutting R72. |
Snapperhead
Intermediate Member
Username: Snapperhead
Post Number: 209
Registered: 2-2002
| | Posted on Monday, April 18, 2005 - 8:03 am: |
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Hello Racer X, yes it is probably a typo in there part......Also in this procedure:
Loop Filter installation: Locate the 10K trimpot and 10uf capacitor supplied with the 400. Solder the wiper of the trimpot to ground (see Fig. 2). Install the 10uf capacitor between one end of the trimpot and TP-9. Observe polarity; the negative (-) lead of the capacitor must connect to the trimpot. Remember to keep leads as short as possible during this procedure.
(See page 6)
I don't have the 10k trimpot or the 10uf Capacitor. I wonder if Radio Shack carries them. Also, what is the wiper of the trimpot that is described?......Thanks
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Racer_x
Intermediate Member
Username: Racer_x
Post Number: 336
Registered: 2-2005
| | Posted on Monday, April 18, 2005 - 4:50 pm: |
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I'm fairly sure they do. Usually a pot will have three or more terminals, leads, prongs - whatever you want to call them. The wiper is the one that the pot is there for. It's the output.
I don't want to sound condescending, but perhaps you should have someone help you with this project, or read a bit on your own to learn some basics. Knowing what the wiper of a pot does is pretty basic stuff. |
2600
Advanced Member
Username: 2600
Post Number: 551
Registered: 7-2002
| | Posted on Tuesday, April 19, 2005 - 12:44 am: |
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Hi Snapperhead,
Is this the metal case one marked "UFO" on the front, or the later plastic-case "Elite" model?
It's a safe bet that even after everything is soldered in place correctly, there will be some adjustment (alignment) issues that have to be taken care of in the radio.
As you've seen so far, this is a bit more complex than installing a noise toy, roger beep or echo board.
A SSB radio that was stable and dependable using its own internal channel selector will become "twitchy" with the Digi-Scan if none of those adjustments are altered to match the new setup. Without a 'scope, it's going to be a game of pin-the-tail-on-the-donkey to get it right after the Digi-Scan is wired in.
And if I haven't made your day already, it's worth pointing out that using an amplifier with this radio may cause the frequency to 'warble' or jump around when you modulate. The two shielded wires lead into the most sensitive part of the radio's internal circuitry. Those wires that join the two units can become accidental antennas, picking up stray power leaking out of an amplifier. When that happens, the radio's frequency will try to change in step with your modulation when an amplifier is running. If you get reports on SSB like "Sounds like somebody is standing on your throat", this is likely the explanation.
Might just fire up and work great the first time. Maybe. And then again, maybe not.
Best of luck and
73
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Snapperhead
Intermediate Member
Username: Snapperhead
Post Number: 210
Registered: 2-2002
| | Posted on Tuesday, April 19, 2005 - 7:45 am: |
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Hello 2600, Thanks for the insight. Well, I'm no Rocket Scientist but I'm pretty handy on a soldering gun, I've already removed MB8719 chip from board, and need to pick up some parts to complete the job. I am aware of getting radio aligned after procedure......I will be sending radio to a well known tech for a complete alignment the right way, Scopes, signal generators, good meters.........I just wanted to save a couple of bucks on wiring this DigiScan up........Well, thanks for all the help you guys............Wish me luck.....73's |
Snapperhead
Intermediate Member
Username: Snapperhead
Post Number: 211
Registered: 2-2002
| | Posted on Tuesday, April 19, 2005 - 7:49 am: |
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Hey 2600, I forgot to answer your first question. It is not the one with Metal case, It has a plastic case and is larger than the metal case one's. It has two small coaxes coming out of device. One labled #1 and #2 and then a positive and negative wire as well. It doesn't have a model number. On back, it just sais Model No. UFO that's it........Thanks
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2600
Advanced Member
Username: 2600
Post Number: 553
Registered: 7-2002
| | Posted on Wednesday, April 20, 2005 - 2:08 am: |
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Sure enough, that one has the whole PLL inside it, except for the Voltage Controlled Oscillator, and a crystal+mixer that reduces the frequency that feeds into the PLL chip. That's the crystal hooked to the clarifier control.
The UFO takes the place of the stock channel selector and PLL chip. One signal that fed OUT of the stock chip now comes from one of the coaxes. The INPUT that went to the old chip feeds out to the UFO on the other coax.
The 5 kHz tuning steps mean that you don't need to 'stretch' the range of the clarifier nearly as much to get complete coverage with no gaps.
The less you stretch the range of the clarifier, the more stable it will be, usually.
73
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Ibacbfreq
Junior Member
Username: Ibacbfreq
Post Number: 29
Registered: 3-2005
| | Posted on Wednesday, April 20, 2005 - 9:55 am: |
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2600: I think the manuals I have would serve mankind better in your hands than mine. If you are interested in them[ all of the redco UFO-DS ect]I will photo copy them and send them to you. I have most of the comscan info also, they are nice 'caus they are smaller[will install inside some moble rigs]but harder to find. 73's, Don |
