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Re: Varactor Diode C Measurement
I'm curious how the 1n4001 compares with purpose built varactor diodes.
Figure 3 here shows it going from about 20 to 5 pf as the reverse voltage goes from 0 to 10 volts. ? ?? Would be interesting to verify that with measurements, trying several different manufacturers. |
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Re: 2n2xx Transceiver R.I.P.
Mike,
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Very cool! I'm trying to get dangerous with Kicad as well, it's a serious set of tools. Being retired now, I no longer have access to the schematic editor and PADS PCB board layout program that I had used for 30 years. I've got a bunch of motor memory to retrain. I believe you went with Jim's schematics from 2001: ? ?? That's a compromise, in that he was building to the arbitrary spec of using only 2n2222's as the active device. The Norcal schematics of 2008 made a bunch of improvements, and addressed any issues that had come up between 2001 and 2008. For example, looks like a much more serious bit of crystal filtering in the IF ? ?? Driving those mixers with 7dB of energy from an si5351 presents a conundrum. The Si5351 datasheet claims it can drive 50 ohms, but then AN619 shows that the CMOS outputs can be programmed to a max of 8ma. The ap note is correct, the Si5351 does not do a very good job driving a 50 ohm load, and loading it up like that will add to the crosstalk between Si5351 channels. Those diode ring mixers want to be 50 ohms at all three ports. With 8ma into 50 ohms, we get something on the order of 5 dBm of power. The 7 dBm mixers will work at 5 dBm, but we're better off having a 6 dB resistive pad between the oscillator and the mixer to absorb any unwanted spurious products coming out of the mixer and keep them from bouncing back into the mixer to produce even more such junk. And after adding that pad, we have lost roughly 8 dB of dynamic range off the top. This is what the uBitx does, and it seems to work well enough. But could do better with a buffer amp between the Si5351 and the resistive pad. I agree about the audio transformer, there's a reason nobody sells them anymore. Many of the audio amp IC's can drive 8 ohms directly, and might be cheaper than that transformer. For a simple audio amp on a CW rig I'd take a look at the SW40+, includes an audio filter for CW. If driving that amp from a diode ring mixer, you may need to add another audio gain stage up front. ? ?? The SW40+ uses an SA612 as the second mixer, we could patch that into the 2n2xx as well if so inclined. We don't really need the dynamic range of a diode ring mixer after stripping off any QRM with the very narrow IF crystal filter.? The SA612 would not need a buffer between it and the Si5351's output, just a resistive attenuator to bring it down to between 200 and 300 mv into SA612 pin 6, which has a roughly 10k input impedance.? The 14 dB of gain that the SA612 provides (vs 6 dB of loss through a diode ring mixer)means either the audio amp or the IF amp can have 20 dB less gain, not clear to me exactly how that extra gain should be distributed. I'd leave the diode ring mixer up front of the IF alone, as that is what will make this better than all the SA612 rigs. This old forgotten Philips ap note is a gold mine for those trying to understand the innards of the SA612: ? ?? Here's some history that conflicts slightly with that short piece on page one of the ap note: ? ?? Jerry, KE7ER On Mon, Dec 16, 2019 at 08:12 AM, Michael Maiorana wrote:
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Re: 2n2xx Transceiver R.I.P. SMT
Rob
¿ªÔÆÌåÓýAbout SMT....... IF you despise SMT crumbs (as I do)? and would rather SEE what you are playing with then I suggest the higher power devices.... like for
resistors... instead of using itsybitsy 0805 ... use size ?2512 SMD Resistors.... seen in green circle in
this link image:
and for transistors...... here are some sizing comparisons..... I settled on DZT2222A-13? as my "go to" SMD transistor after losing way too many MMBT2222A to the carpet gods.
This was a water sensor project to dump air
conditioner condensation overflow water:
On 12/16/2019 11:12 AM, Michael
Maiorana wrote:
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Re: 2n2xx Transceiver R.I.P.
Rob
¿ªÔÆÌåÓýIt saves and displays just fine here. Nice work. On 12/16/2019 11:12 AM, Michael
Maiorana wrote:
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Re: 2n2xx Transceiver R.I.P.
Here's what I have so far. Hopefully this will be legible as an inline image. I'm a Kicad noob, so be gentle :) I used Jim's original design with the roll-your-own mixers. This is the receiver only. There is no VFO, transmit mute or audio amp. My issue with the discrete audio amp as designed by Jim is that hard to find audio transformer. I'm not sure if I should add audio amplification to this board or just do the audio functions on a different board. Thoughts? I plan to use an Si5351 ebay board and an arduino uno as a VFO/LO to get it running (commonly available code), then possibly design?a simple, low power vfo/display. My intention is to use mostly surface mount parts (0805 size resistors and caps, SOT-23 size transistors and diodes). Opinions are welcome! Best regards, Mike M. KU4QO On Sun, Dec 15, 2019 at 9:46 AM Mike Maiorana <zfreak@...> wrote:
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Re: Varactor Diode C Measurement
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For my own amazement, measured for comparison two diodes, MVAM109 and BB910. |
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Re: Varactor Diode C Measurement
Rob
¿ªÔÆÌåÓýHey Chuck..... what does this mean.... "All stabilized at room temperature for measurement."
On 12/16/2019 09:27 AM, Chuck Carpenter
wrote:
For my own amazement, measured for comparison two diodes, MVAM109 and BB910. |
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Varactor Diode C Measurement
For my own amazement, measured for comparison two diodes, MVAM109 and BB910.
A schematic of the N5IB design?test fixture** is attached. All stabilized at room temperature for measurement. ?????????????? Capacitance, pF V??????? MVAM 109????? BB910 0????????? 750????????????????? 52 1????????? 481????????????????? 35 2????????? 340????????????????? 27 3????????? 234??????????????? 22 4????????? 152????????????????? 17 5????????? 100????????????????? 13 6????????? 66??????????????????? 9 7???????? 45??????????????????? 7 8???????? 33??????????????????? 6 9???????? 27????????????????????5.9 10?????? 23???????????????? 5.73 11?????? 21?????????????????? 5.59 12?????? 20?????????????????? 5.45 Highest voltage available from the battery. The capacitance range of the BB910 is similar to the 60 pF section of a polycon often used with HF?VXOs. The MV-209 has a comparable C range. ** N5IB produced a kit of the fixture, since retired.? Fairly easy to build one from?parts on-hand. -- Chuck, W5USJ (ex K2OFN) Point, Rains Co, TX? EM22cv |
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Re: 2n2xx Transceiver R.I.P. ADE-1-24 specifications
Rob
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That bitx20 thread on the ADE-1-24 is rather confusing. |
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Re: Plug and Play Receiver
Howard,
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On second thought, your modules could be a fine way to teach radio. Modules start to make a lot of sense as radios become more complex. Many who design radios for a career have created their own modules to play with new concepts. As you suggested, a DC receiver could be busted down some. Perhaps demo a very simple diode detector with hi-z phones for local AM stations.. Then a bare bones SA612 (with 9v battery, coil+cap for LO, hi-Z phones, wire antenna). An inductor tuned with a brass screw for the LO is cheap and approachable. Same rig could hear your 40m transmission by adjusting the LO coil and cap. Then add an audio amp, RF gain pot on the antenna, audio gain pot, RF filter, RF amp, AF filter, a back-to-back diode audio limiter, a stable si5351 vfo. From there, perhaps a second SA612 and a crystal IF filter, agc,? audio into an RPi. Spend the remainder of the hour showing how to code DSP algorithms in python. I might want to play with all that once you're done with it. Jerry, KE7ER On Sun, Dec 8, 2019 at 08:12 PM, Jerry Gaffke wrote:
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Re: 2n2xx Transceiver R.I.P.
That bitx20 thread on the ADE-1-24 is rather confusing.
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And to some extent, so is the ADE-1 datasheet: ? ?? The ADE-1 pins are numbered like a DIP IC, pins 1,2,3 down one side and 4,5,6 going up the other side as shown in the top left of page 1 of the data sheet. Looking at the schematic diagram in the lower right of page 1, pins L, I, R (local oscillator input, IF output, and RF input) are at pins 6,2,3 respectively. We're assuming here that this is a receiver, with the RF coming in getting converted to the IF. The three pins shown as grounds are not internally connected. The bottom of the L coil is pin 1, the bottom of the R coil is 4, and the pin on the other side of the diode bridge from I is pin 5. There is no connection (other than magnetic fields) between the L, I, and R sections. I think this forum post spells out the final consensus: ? ? ? ?/g/BITX20/message/54143 The only difference found in the ADE-1-24 from the standard ADE-1 is that pins 2 and 5 have been reversed.? Most of us would never notice. But if you have an ADE-1-24 and you want it to work *exactly* like an ADE-1, you should probably swap pins 2 and 5. As they note in the forum, grounding pin 5 as shown for the standard ADE-1 (pin 5 is the center tap of the transformer whose other winding is L) may cause less leakage from L (the local oscillator) into I (out to the intermediate frequency amp).? ? Dropping an ADE-1-24 into pads designed for an ADE-1 would reverse this, favoring the RF port for maximum isolation from the local oscillator.? Just looking at the schematic drawing in the datasheet, the L and R ports appear interchangeable. However, the datasheet shows significantly better numbers for SWR looking into the R port than the L port. ? The ADE-1 datasheet says that the L and R ports are good from 0.5 to 500 mhz, The I port however, is good from DC to 500 mhz, since there is no need for magnetic coupling from the diodes where the mixing occurs out to pins 2 and 5. So, for example, if used as the final mixer in a receiver, make sure the audio is coming out of the I port.? Other than this, all three ports are mostly interchangeable. Jerry, KE7ER On Sun, Dec 15, 2019 at 06:23 AM, Jerry Gaffke wrote:
Looks like they were made by MiniCircuits as a custom build for a customer in 2006: |
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Re: 2n2xx Transceiver R.I.P.
Primary attraction of this rig is the "back to basics" analog design,
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nothing hidden in IC's. An LM386 for the audio amp is simple, works from 5-15 volts, but is not for the audiophile. From wikipedia:? "The LM386 was invented by Ernie Leroy Long at Motorola in 1969. It was originally for part of a fuel injection system for a Ford Car." If true, that makes it 7 years younger than the 2n2222.? Here's an interesting look at a future proof replacement:?? Many similar analog audio IC's have become obsolete as the?industry moves on to class D switching amps. But those new amps can create RF hash. Fiddling with caps in a crystal ladder filter works to adjust bandwidth, but I assume that the passband shape does not remain optimal. Also, the extra cruft can add leakage around the filter, impacting the stopband. Lots and lots of parts if you build something like the 2n22xx with all discrete devices. If you are buying by the reel, they are very nearly free. Jerry, KE7ER On Sun, Dec 15, 2019 at 06:46 AM, Michael Maiorana wrote:
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Re: 2n2xx Transceiver R.I.P.
Thanks Jerry.? I spent some time this morning looking at the different versions of this rig, from the original to the Norcal version. The first thing that struck me was how crowded and complex the Norcal board looks when built. I'm sure they spent a tremendous amount of time with the redesign and layout of that board. Not for the faint of heart.? They made some substitutions, like replacing the discrete?mixers with ADE-1 mixers. I am curious as to why Norcal kept the audio amp the way they did instead of going to a simpler integrated amp. Any ideas? They also did away with the variable bandwidth IF filter.? I thought?it might be fun to lay out the receiver section using mostly surface mount parts. Not necessarily to get it smaller, but instead to make it less congested.? I bought a couple of the Si5351 boards from Ebay. I could use those as the VFO, with plans to go to a more elegant (lower power) solution later. This sounds fun, but maybe it's just because I had too much coffee this morning. I'll start adding things to Kicad and see where I end up.? Best regards and 73 Mike Maiorana KU4QO On Sat, Dec 14, 2019 at 7:20 PM Jerry Gaffke via Groups.Io <jgaffke=[email protected]> wrote: The Raduino used on the uBitx consists entirely of a 5v regulator, an Arduino Nano clone, an Si5351, and a standard 16x2 LCD with backlight. |
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Re: 2n2xx Transceiver R.I.P.
Looks like they were made by MiniCircuits as a custom build for a customer in 2006:
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? ??/g/BITX20/topic/4104916#17354 Other posts in that thread indicate that they are pretty much identical to a standard ADE-1 but the pins got wired up a little bit different. My guess is that somebody built a few thousand PC boards for the ADE-1, and then realized they could get better performance with the ports wired up differently. Jerry On Sat, Dec 14, 2019 at 10:00 PM, n3fel@... wrote: I am curious as to the possible substitution of the mini circuits ADE-1 with imported ADE-1-24 devices.? The look of the two seemed to be identical.? Has anyone found success with the latter?? ?How¨¤rd, n3fel |
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Re: 7 MHz Oscillator Ideas
OK, last time, I promise.
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Jerry and All, I?expect we've been thinking grapefruit and tangerines...related but not the same...8^) Varactors used to tune an entire?AM or FM band?with a max C of 350pF or so and a min C of about 30pF at 12 V. I'd expect them to be like you described. The varactors I'm using, BB910 or MV209,?have a max C of about 60pF or so and a min C of about 6pF at 12 V, same percentages but minimal effect in the circuit where used.? My choice of these two (or other similar) was related to the 60pF section of a polycon variable often used?in VXOs. Anyway, Fun Stuff... On Sat, Dec 14, 2019 at 09:14 AM, Jerry Gaffke wrote:
? -- Chuck, W5USJ (ex K2OFN) Point, Rains Co, TX? EM22cv |
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Re: 2n2xx Transceiver R.I.P.
The Raduino used on the uBitx consists entirely of a 5v regulator, an Arduino Nano clone, an Si5351, and a standard 16x2 LCD with backlight.
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Power consumption is 40ma without the display, the display (mostly the backlight) sucks another 20ma. ? ??/g/BITX20/message/52886 The linear regulator is typically powered from the main 12v supply, so that Raduino heats the room with 60ma*12v = 0.72 Watts. From table 3 of the datasheet ? ?? the Si5351 with all three outputs running typically draws 22ma, this could be either a 2.5 or 3.3v rail.? So as little as 0.022*2.5v=0.055 Watts if powered from an efficient buck mode switcher. The switcher might be 90% efficient, but we don't need all 3 outputs of the Si5351. The switcher would also have to be extremely quiet, but that is possible to do. Most designs just use a linear regulator. Those Nano clones are not a good choice if going for minimum power. And the display does not need to leave the backlight on much, not at all if reflective. A well done microcontroller plus display could be down in the microamps, And you don't really need the display at all: ? ??/g/qrptech/message/386 So the Si5351 is the power hog in the VFO. A bigger power hit on receive for anything based on the 2n22xx is all that analog stuff in the IF, hard to get around it if you want the dynamic range that the 2n22xx has to offer. If you don't feel a need for the dynamic range (or a need to tinker with a good basic analog design), you may as well build another SA612 rig. The ADE-1 is $3 each (in 100's), the toroids $0.20, an Si5351 $1, PN2222's $0.02, crystals $0.20. Lots of $0.02 parts, but this could be kitted up cheaply. Here's Jim's post:?
? ? /g/qrp-tech/message/19773 Supporting the 2n22xx took a year out of his life, he's not keen to repeat that.
On Sat, Dec 14, 2019 at 03:00 PM, Michael Maiorana wrote:Reading that closely, I see nothing suggesting he would object to somebody kitting something?similar to the 2n22xx but different enough (vfo and pa?) that he can claim to?no longer be the designer.? Worth asking.? We could offer a filter for his email that discards anything from qrptech forum members. Doug might be able to enlighten us further on what Jim might think. If anybody is serious about proceeding.? (I am not.) Jerry, KE7ER
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Re: 2n2xx Transceiver R.I.P.
On Sat, Dec 14, 2019, 11:43 AM Jerry Gaffke via Groups.Io <jgaffke=[email protected]> wrote:
Ack! Not me! I have a day job :) Do you know what the power supply current requirements would be for the synthesizer, LCD and Arduino? I still marvel at my SW40+ that uses only 25mA on receive. I think it would be fun to build this up with modules. Each module / function would be fairly easy dead-bug style, then connect the bits and test.? Mike M Ku4qo |
Chuck Carpenter
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