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Fusebreaker
Intermediate Member
Username: Fusebreaker
Post Number: 133
Registered: 3-2004
| | Posted on Wednesday, September 07, 2005 - 6:41 pm: | 
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is there any replacement diodes made that will work in place of one of these super diodes that no one seems to know about?
Im trying to break the super diode conspiracy LOL |
Hollowpoint445
Advanced Member
Username: Hollowpoint445
Post Number: 755
Registered: 6-2004
| | Posted on Wednesday, September 07, 2005 - 9:11 pm: |
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What's wrong with adding a small inductor in series with the varactor diode? It seems to add plenty of swing to the existing diode.
There are all kinds of varactor diodes out there. I don't know if they offer more capacitance than the ones currently used in CBs, but it's worth the few bucks that surplus electronics companies charge for them to find out if you're that interested.
As I understand it the super diodes were made only for a short time and aren't anymore. I never really saw the need for them so I've never used one. |
Slowhand
Member
Username: Slowhand
Post Number: 70
Registered: 7-2005
| | Posted on Wednesday, September 07, 2005 - 10:07 pm: |
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The inductor works, also try adding 2 varactor diodes in series |
Fusebreaker
Intermediate Member
Username: Fusebreaker
Post Number: 135
Registered: 3-2004
| | Posted on Wednesday, September 07, 2005 - 11:22 pm: |
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yea thats what i was thinking they were not made anymore i wanted to make a 148 slide from 27.455 to 27.435 is why i am asking will the choke do that? |
Patzerozero
Senior Member
Username: Patzerozero
Post Number: 1415
Registered: 7-2004
| | Posted on Thursday, September 08, 2005 - 8:31 pm: |
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4.7uH should, 10uH WILL-but at risk of even LESS stability then the 4.7
4.7 in my xl goes DOWN 14kc & up 6.5.
2 varactors in series didn't cover 1 channel/10kc |
Fusebreaker
Intermediate Member
Username: Fusebreaker
Post Number: 139
Registered: 3-2004
| | Posted on Thursday, September 08, 2005 - 11:08 pm: |
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ok thx Patzerozero |
Kid_vicious
Advanced Member
Username: Kid_vicious
Post Number: 588
Registered: 9-2004
| | Posted on Friday, September 09, 2005 - 12:16 am: |
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fusebreaker, the super diode was contracted to be manufactured for Secret CB exclusively.
once their stock ran out, there were no more.
i have tried for a while to find any of the old secret CB kits on the used market.
*bay may have one from time to time, but if anyone still has one they know how valuable it is to some.
if i were you i would go with a 5.6uh choke in series with the varactor.
i also dont like to power a clarifier mod by putting a wire to pin 3 of the MB3756. i think this gives poor voltage regulation. better to power it from the main supply and build your owm voltage regulator that provides 8 volts dc.
matt |
Fusebreaker
Intermediate Member
Username: Fusebreaker
Post Number: 140
Registered: 3-2004
| | Posted on Friday, September 09, 2005 - 2:01 pm: |
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good information,Kid_vicious
thank you |
Slowhand
Member
Username: Slowhand
Post Number: 71
Registered: 7-2005
| | Posted on Saturday, September 10, 2005 - 2:50 am: |
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I believe its possible to add a 10k switch to a 148. Then you wouldn't need your clarifier to slide so far, which by the way makes it difficult to adjust without a 10 turn pot. I think this is the how-to, just be sure to use anti-static procedures or you can easily fry the PLL.
10 KC JUMP:
Basically, you need to either add voltage or ground pin #16 on the MB8719 PLL.
For a 10 Kc UP,
Cut trace to pin #16 on the PLL.
Install a 4.7K resistor across the cut you made.
Using a SPST switch, one side of the switch goes to the cut-side of pin #16.
The other side of the switch goes to pin #9 of the PLL. (8 volts)
When you apply the 8 volts, this pulls pin #16 high causing the 10 kc jump up.
This will not work on all channels.
For 10 Kc DOWN
Ground pin #16 using a SPST switch. No cut to the PLL is necessary.
Pulling pin 16 low will cause it to jump down 10Kc.
This will not work on all channels.
For a 10 Kc UP and DOWN switch:
Perform the trace cut/resistor addition described above.
Use a SPDT switch and wire as follows:
Center of switch goes to pin #9 of PLL (8 volts)
One side of switch goes to the cut side of pin #16.
The last side goes to pin #18 of PLL (or ground)
This will allow you to jump 10Kc up or down.
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Hatchet
Junior Member
Username: Hatchet
Post Number: 18
Registered: 7-2004
| | Posted on Saturday, September 10, 2005 - 11:01 am: |
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NTE-612 is a good replacement for the super diode |
Fusebreaker
Intermediate Member
Username: Fusebreaker
Post Number: 152
Registered: 3-2004
| | Posted on Saturday, September 10, 2005 - 11:50 pm: |
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the 10 k switch only works on the channels that jump 20 kc like btween 3 and 4 HAtchet thx for info and thx everybody as well |
Fusebreaker
Intermediate Member
Username: Fusebreaker
Post Number: 153
Registered: 3-2004
| | Posted on Saturday, September 10, 2005 - 11:59 pm: |
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it apears that anything nte612 to nte615 are all varacters the only difference is the CT level but i dont know what ct means? |
Jellybean
Member
Username: Jellybean
Post Number: 86
Registered: 1-2002
| | Posted on Sunday, September 11, 2005 - 9:11 am: |
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Fusebreaker have you or anyone ever done a 5kc switch instead of doing the slide mods? I'd like to do one for a Grant 8719. I have a cpi that has one, but I wasn't sure if this pl would allow a 5kc switch.
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Slowhand
Member
Username: Slowhand
Post Number: 72
Registered: 7-2005
| | Posted on Sunday, September 11, 2005 - 10:07 am: |
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You can switch in and out out some extra capacitance via relay at the crystal, but you'll have to experiment to find the correct value. |
Fusebreaker
Intermediate Member
Username: Fusebreaker
Post Number: 159
Registered: 3-2004
| | Posted on Sunday, September 11, 2005 - 3:20 pm: |
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jellybean i think there is a mod for 5kc switch but im not familar with how to do it.Yankee might know.I know theres a mod that will give you 26815 to 28085 but it disables the channel selector and use`s 7 toggle switchs to select the frequency you want. |
Jellybean
Member
Username: Jellybean
Post Number: 87
Registered: 1-2002
| | Posted on Sunday, September 11, 2005 - 5:05 pm: |
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Thanks, Slowhand, Fusebreaker. I've seen the 10kc, but I would love to do a 5kc and put the clarifier back so it's not so touchy. I have a 10 turn pot, but I'm not to crazy about that. If it had a center detent it would do fine. Do they make a 10 turn with a center position? I'm not that creative or good. But I can solder!  |
Fusebreaker
Intermediate Member
Username: Fusebreaker
Post Number: 160
Registered: 3-2004
| | Posted on Sunday, September 11, 2005 - 6:45 pm: |
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I dont know but i would love to have a ten turn.It would make the clarifier act like it shoud when it is expanded so high. |
Patzerozero
Senior Member
Username: Patzerozero
Post Number: 1453
Registered: 7-2004
| | Posted on Sunday, September 11, 2005 - 7:04 pm: |
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the standard 3 switch mod gives 26.815-28.085, & does NOT disable the channel selector. the 10kc switch & standard 6 kc slide is not THAT touchy. mine slides total 20 kc, 14 up & 6 down, on the stock clarifier control. touchy, maybe just a tad, but for 10 years, has never been a problem. have never had anybody on SSB say I AM off freq, when i tune to them. compared to radios known to be ON, at worst, i can be 100 or 200 Hz down-but that can be blamed on where i prefer to listen, moreso then what radio says is true center. 10 minute drift can be as bad as 500 Hz when weather is cold, otherwise it drifts less then 200 Hz til warm. |
Bigbob
Senior Member
Username: Bigbob
Post Number: 2197
Registered: 12-2001
| | Posted on Sunday, September 11, 2005 - 11:13 pm: |
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I would still be using my p-400 except the speaker went poof,had 25 kc swing with the super diode and 10uH choke 10 up 15 down,instead of putting two varactors in series they should be in paralell to double their reactance,you may have to increase voltage to them slightly to take advantage,I did the voltage increase myself,by using a zener diode and 47mfd cap to make a seperate voltage regulator for the clarifier circuit,later changed to a 317t to fine tune the voltage,I love clarifier circuits.Bigbob |
Slowhand
Member
Username: Slowhand
Post Number: 73
Registered: 7-2005
| | Posted on Monday, September 12, 2005 - 4:12 am: |
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Bigbob, I tried the 2 varactors in parallel in a TRC457 but I got better results with them in series. Only time I've tried it, mabe a fluke, but it's not a big problem to try it both ways. |
Fusebreaker
Intermediate Member
Username: Fusebreaker
Post Number: 163
Registered: 3-2004
| | Posted on Monday, September 12, 2005 - 1:35 pm: |
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Wow i see the chokes are only 3 for $1 im gonna by an assortment and expirent with diferent levels until i get the results i need thanks guys |
Fusebreaker
Intermediate Member
Username: Fusebreaker
Post Number: 164
Registered: 3-2004
| | Posted on Monday, September 12, 2005 - 1:39 pm: |
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Patzerozero i am fimilar with the mod your saying but i have one that you cut the wires that connect the channel selector and and put on/off switch`s on 10 through 16 to ground by grounding certain pins it changes the pll programing but i dont like that mod cuz you have to have a frq counter and for mobile use it is a pain to read the paper what channels are where.I want to keep the 2 switch mod since im going to run mobile. |
Kid_vicious
Advanced Member
Username: Kid_vicious
Post Number: 599
Registered: 9-2004
| | Posted on Tuesday, September 13, 2005 - 7:04 pm: |
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fusebreaker, the mod you read about is not really a "mod". it is just the most basic way of controlling a PLL chip's pins to apply either voltage or ground. that is all the channel switch is doing anyway.
the best version of this i've found is the 2 pole 6 position switch.
one switch, one hole, 26.815 to 28.045, and channel selector still works. you should be able to find it online somewhere. i found a diagram awhile ago.
matt |
