PART NUMBER FOR "SUPER VARACTOR DIODE"

[unit_399]

Can someone please tell me the part number for the so-called "SUPER VARACTOR DIODE??" I have several numbers on a list somewhere, but can't put my hands on it. Thanks.

- 399

 

[Handy Andy]

I thought it was an SVC251 - but it's been obsolete'd - so they can still locate info for the SVC211 - the FM tuning one that has a dual varactor.

Why this part?

Well, look over the Galaxy schematics of their PLL you'll see they used TWO varactors to provide the pF in capacitance change to provide the coverage.

Might be work a look.

 

[brandon7861]

I accidentally ordered some BB175X's not looking at the physical size (SOD-523-2, which is almost small enough to be useless to me). They are supposed to be quite linear and do about 5pF to 60pF from 1v to 12v, but I haven't tried them in a CB yet.

 

[Klondike Mike]

Here's one for your list; Motorola MV1403. Through hole. I don't see anyone having any stock. There seems to be some MV1405's available.

 

[unit_399]

Thanks for all the replies. I am looking to buy as many different ones to test out some clarifier mods I've been thinking about. I remember that the old SECRET CB "Super diode" was made by Siemens. I'll dig thru their catalog and see what's available. Again thanks
399

 

[Handy Andy]

You might want to also find that swinger choke too.

 

[metalguy66]

Some dude on Ebay has some DKV6510 but he's overseas and wants a fortune for them. How about the siemens BB112? There's alot of them available cheap in China.

 

[nomadradio]

BB12 sure looks like it qualifies. Any varactor meant to tune a AM-broadcast receiver should be in the ballpark.

And nobody calls it the "Super Drift" diode?

73

 

[metalguy66]

BB12 sure looks like it qualifies. Any varactor meant to tune a AM-broadcast receiver should be in the ballpark.

And nobody calls it the "Super Drift" diode?

73

Well, I just replaced the stock varactors in my '78 Sears Roadtalker SSB with Motorola MV1404 Hyper-Abrupt Varactor Tuning Diodes (96 - 144 pF) and it gave me about 6.5khz up and 5.5khz down worth of "slide". Before, it had like 1.5khz each way. These suckers are highway-robbery but here's the link if anyone wants to buy them:

Qty. 2 Motorola MV1404 Hyper-Abrupt Varactor Tuning Diodes 96 - 144 PF | eBay

Find many great new & used options and get the best deals for Qty. 2 Motorola MV1404 Hyper-Abrupt Varactor Tuning Diodes 96 - 144 PF at the best online prices at eBay! Free shipping for many products!

www.ebay.com

I also have some NTE611 varactors and some 5.6uH and 10uH inductors ordered.
I will try those on my next radio.

Nearest I can tell, they used to refer to the varactors as "Super Clarifier Diodes" and the Chokes as "Super Sliders" which you'd hook between the cathode of the varactor and ground to get even more range..

 

[Klondike Mike]

I put one of these (M65 made by ??) in my Cobra 2000 back in the day. It did about 40khz up and 10k down. Yikes!! Too much and had to be pulled.

 

[AudioShockwav]

Yes, when your stretching it out that much it gets too touchy, then you have to add a 10 turn potentiometer or a multi turn reduction drive to try to slow down the clarifier like back in the day.



73
Jeff

 

[metalguy66]

Yep.. Those 10 turn pots are great if you're doing say 12Khz or more each way, which as you pointed out is easily the case with some of the clarifier mods out there..

Personally, If i'm just sliding 5khz each way, I like a good high precision single turn pot.. That's just me.. I don't have a hard time making .01Khz adjustments, so it;'s fine.. Cheaper (lower quality) pots (or dirty ones,) It's a problem...

While we are talking about useful additional parts, here is a 4-bit binary encoding rotary switch for $6.32 from Mouser.

https://www.mouser.com/ProductDetail/NKK-Switches/FR01AR16PB-S?qs=WUOmdsDZVjjwvBul5BhJEw%3D%3D

This is the easy/good way to do a channel expansion mod to most PLL-IC-driven VFOs.. 16 rotary positions gives you every possible combination of states for the 4 highest-order bits (pins of the IC) of the divider circuit in the PLL-IC.

.......PIN....................................SWITCH POSITION

 

[brandon7861]

There really isn't any point in having more than 5kHz each way as most channels are spaced 10kHz apart. If you want to go up 6kHz, just go up one channel and down 4kHz. There is no reason to use the clarifier to go to the next channel on the dial. Where the channels are further apart, it is because of RC frequencies, and as someone who flies RC planes, it would be super cool if people just kept their radios off those channels (please and thank you).

 

[metalguy66]

Hey I just found this on Ebay:

SLIDER DIODES - Pkg of 5 For CB/10 Meter Radios QRP PLL Tuning VARACAP Clarifier

claims:

• The Range Is 4.2pf to 60pf With Variable Voltage Applied
• Can Be Used To Expand PLL Circuits Far Beyond Their Frequency Cutoff
• Better Than Original "Super Slider"Diodes!

For a grand total of $12.45, you get 5 of them. I just ordered a set. I'll report back after I try them out.

 

[Enterprise312ok]

There really isn't any point in having more than 5kHz each way as most channels are spaced 10kHz apart. If you want to go up 6kHz, just go up one channel and down 4kHz. There is no reason to use the clarifier to go to the next channel on the dial. Where the channels are further apart, it is because of RC frequencies, and as someone who flies RC planes, it would be super cool if people just kept their radios off those channels (please and thank you).

When I key down I dont want little planes to crash;so I will try to stay of the alpha channels, sorry to all the rc pilots I have crashed