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Re: Power supply fuses
Hello? For my uBitx I use a Pacific Antenna kit named VoltTattler. This montage has the following features: - Simple through-hole construction - Draws only around 1 mA in normal use.? - Reverse polarity protection. - Programmable Thresholds over a range of 4V to over 27V. - Single button programming with audio feedback. - Audible announces activation with power on and indicator with LED flashing green. - Audibly announces by Morse code when input voltage exceeds user programmed thresholds. - Flashing Red and Yellow LEDs indicate that a voltage limit has been exceeded. - 3V digital status signals are available on a header - Cheap protection for low voltage DC equipment. interesting to avoid inversions of polarities and portable QRP, in battery operation to know the state of health of your batteries. 73 QRO from F1BFU 2018-06-07 21:10 GMT+02:00 entilleser via Groups.Io <entilleser@...>: The "Fix reverse polarity" section on suggests a 0.5A fuse for the "rig" and 2A fuse for the "finals," but does not specify which wire is which.? The schematic says that the brown wire is "PA-PWR," but I am too much of a newphyte to be certain if this means the same as "finals" or "rig." |
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Re: K5BCQ kits in BITX40
#bitx40
I was wondering if my 2 AGC boards were sent yet? Thanks VE1BWV joe Basque On Wed, Jun 6, 2018, 11:18 AM Don, ND6T via Groups.Io <nd6t_6=[email protected]> wrote: For those wondering if the K5BCQ AGC and ClickFix kits work with the BITX40, they do! The AGC works just as well as in the ¦ÌBITX and the ClickFix is, by far, the quietest modification that I have tried. The latter uses the PTT line for keying the receive preamp but that is all explained on the web site. No software changes are necessary unless you use the AGC board as an S meter source (which I recommend) and that is only to calibrate the display to accommodate the improved dynamic range. 73, Don |
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Re: Power supply fuses
I'm a newbie on here and just dipping my toe into the world of BITX's
If you're running the radio at 13.8v is there enough wriggle-room to cope with a 1.4v drop using a bridge rectifier? Reverse polarity diodes are a blunt instrument when protecting equipment, you still have to find a replacement fuse if you're in the middle of nowhere. I've used a bridge rectifier with the incoming 13.8v on the AC inputs and, whatever way round you connect it, you will always get the correct polarities on the +ve and -ve sides. Martin |
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Re: RF power chain mods and improvements..
Gordon Gibby
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Re: Power supply fuses
¿ªÔÆÌåÓýSpeaking of Fusing and
Over-Current protection. I am experimenting with an LT6108 for a Real Fast over current limiter. The circuit show is my 2 PCB, the LT part is fussy about getting reset. I have it Latch Up, so you power down to reset. The ap note says less than 5uS to shut down. I got new PCBs coming.? The first go around I could not get LT to reset, it needs a 10uS pulse to get out of over current condition.? I
have a tiny (SOT 23-6) Pic programmed to do that.? The PCB is about 1
3/4" x 1 1/8".? Should fit on back inside panel somewhere
where power comes in on most chassis?
So 5uS seems like a really fast fuse to me? 73's Mike, WA6ISP On 6/7/2018 12:14 PM, ajparent1/KB1GMX
wrote:
Finals, PA-PWR, output devices... the same. -- Mike Hagen, WA6ISP 10917 Bryant Street Yucaipa, Ca. 92399 (909) 918-0058 PayPal ID "MotDog@..." Mike@... |
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So it's narrow when the key is down continuously, but a string of dots is 1khz wide?
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That would be envelope shaping.? Has to do with how quickly the transmitter turns on and off when you key it. Here's somebody who has looked at this: ? ??/g/BITX20/message/51423 On Thu, Jun 7, 2018 at 12:37 pm, K3OS wrote:
Just got a v3 board running today.? I was monitoring CW on my IC7300 and noticed that when transmitting, i.e., a string of dots or dashes, the bandwidth would widen to 1Khz then return to very narrow.? ?This occurred at a periodic rate if I held the dot or dash lever.? Internal keyer was used.? When sending text the same issue occurred but it was more difficult to spot.? Initial test was 40 meters, 12 watts out, but same results on 20, 8 watts out all into a dummy. 12.2VDC power supply.? |
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Re: RF power chain mods and improvements..
Here's another shot at embedding my Mouser search, maybe this one will work:
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? ?? On Thu, Jun 7, 2018 at 12:37 pm, Jerry Gaffke wrote: Here's a Mouser search for stuff with Vce of 12v+, Ic of 600ma+, Ft of 300+: |
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K3OS
Just got a v3 board running today.? I was monitoring CW on my IC7300 and noticed that when transmitting, i.e., a string of dots or dashes, the bandwidth would widen to 1Khz then return to very narrow.? ?This occurred at a periodic rate if I held the dot or dash lever.? Internal keyer was used.? When sending text the same issue occurred but it was more difficult to spot.? Initial test was 40 meters, 12 watts out, but same results on 20, 8 watts out all into a dummy. 12.2VDC power supply.?
Any clues to why this happens and what can be done? Gary K3OS |
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Re: RF power chain mods and improvements..
Here's a Mouser search for stuff with Vce of 12v+, Ic of 600ma+, Ft of 300+:
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? ??1z0y4diZ1z0y4ciZ1z0w69sZ1z0wajfZ1z0s5p6Z1z0w3wpZ1z0w6rxZ1yxzg4rZ1z0w65eZ1z0w693Z1z0w6r0Z1z0w64vZ1z0w6i8Z1z0w6xnZ1z0wa4fZ1z0w6fhZ1z0vzb6Z1yyb05lZ1z0w6ylZ1yy9vthZ1z0w5kaZ1yyyiibZ1z0wa61Z1yyziiqZ1yyzhtqZ1yyzh82Z1yyzht3Z1yyzhfuZ1yyz8ghZ1yyzhg7Z1yyzheyZ1yyyjktZ1yix7auZ1yyzh3lZ1yyzg3zZ1yyyiicZ1yyzh56Z1yyzhofZ1yyyt0tZ1yyzhtgZ1yyzhg2Z1yyx4b4Z1yyx4b1Z1yyx39cZ1yyx41aZ1yyx4qeZ1yyx39eZ1yyzhiuZ1yyx41d Most of the hits are 2n2222 variantes. This one looks promising, dissipates over a Watt if you give it some copper: ? ??https://www.mouser.com/ProductDetail/Diodes-Incorporated/DXT2222A-13?qs=sGAEpiMZZMshyDBzk1%2fWi5S7e8F%2fC6%252bHGC8aVJqhk4k%3d That Nexperion has a data sheet with both the SOT-23 and the TO-236, just says 250mW max, I'd guess the TO-236 can do more: ? ?? And if you want to try something that isn't 55 years old, there's this, dissipates over a Watt: ? ?? There's more, but the above show we could stick with 2n2222 and friends at $0.15 each in quantity. All the cheap ones are surface mount, through-hole is now a weird specialty item.? Perfect for hfsignals if they roll the board. I'd bet we could use them in the existing through-hole positions, standing them up on their legs and soldering some copper foil to the tab.? Though the through hole 2n2222a in the metal can would make a lot more sense for re-working the old boards. Jerry, KE7ER On Thu, Jun 7, 2018 at 11:38 am, Jerry Gaffke wrote:
What's absolutely astounding is that it's still a good choice. |
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Power supply fuses
The "Fix reverse polarity" section on ubitx.net suggests a 0.5A fuse for the "rig" and 2A fuse for the "finals," but does not specify which wire is which.? The schematic says that the brown wire is "PA-PWR," but I am too much of a newphyte to be certain if this means the same as "finals" or "rig."
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Re: RF power chain mods and improvements..
In the old parts box I have Ck722s, 2n107, a few SB100,? 3n35 and 36(tetrodes!)
and the first JFETs (GM almost 900uS, modern parts like J310 are about 20,000) also a pot load of the?early computer transistor 2n1304,5,6 (FT of 15mhz). Keep in mind when the CK722 was introduced at $7.50 each it was labeled as the first transistor for hobby use at an affordable price!? For that year $7.50 would buy about 35 loves of bread then.?? Another oldie was the 2n5109, they were in use back in 1970 in communications gear. The real roachs are the 12ax7, 6AU6, and 6146 (and other hollow state devices).? Someday I have to do a simple compact SSB transceiver using 5899 and 6CW4s and maybe 5763 (QRP).? ?Heater circuit will likely use more power than uBITX at full transmit power on 80. Allison |
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Re: RF power chain mods and improvements..
What's absolutely astounding is that it's still a good choice.
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The 2n2222a has slightly better specs than the original 2n2222, but not by much. Jerry On Thu, Jun 7, 2018 at 11:22 am, ajparent1/KB1GMX wrote:
>>>So when it was introduced, I was maybe just starting to think about? building a crystal radio with razor blades and toilet paper tubes.<< |
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Re: RF power chain mods and improvements..
Jack Purdum
I forgot the speaker's name, but at the FDIM conference this year, he referred to the 2N2222 as the "cockroach of transistors". Jack, W8TEE
On Thursday, June 7, 2018, 2:16:45 PM EDT, Jerry Gaffke via Groups.Io <jgaffke@...> wrote:
Yup, almost as oldie as me. From? ? ?? "Since its initial product launch by Motorola at the 1962 IRE Convention, the 2N2222 has become the most widely used and universally recognized?transistor of all time. Billions of units have been manufactured over the past 45 years and there is continuing high volume annual production." So when it was introduced, I was maybe just starting to think about? building a crystal radio with razor blades and toilet paper tubes.? Jerry On Thu, Jun 7, 2018 at 10:48 am, ajparent1/KB1GMX wrote: Yes, 2n2222A are an oldie. |
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Re: RF power chain mods and improvements..
>>>So when it was introduced, I was maybe just starting to think about? building a crystal radio with razor blades and toilet paper tubes.<<
It was notable as it wasn't germanium and could handle a bit of power too. By then I'd already blown up a few 2n107s, 2n170s and anything else I could scrounge and others trying to get audio gain and RF selectivity.? ?It would take about 3 years to get to, regens don't hack it, and build my first superhet for 2-6mhz. Allison |
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Re: RF power chain mods and improvements..
Yup, almost as oldie as me.
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From? ? ?? "Since its initial product launch by Motorola at the 1962 IRE Convention, the 2N2222 has become the most widely used and universally recognized?transistor of all time. Billions of units have been manufactured over the past 45 years and there is continuing high volume annual production." So when it was introduced, I was maybe just starting to think about? building a crystal radio with razor blades and toilet paper tubes.? Jerry On Thu, Jun 7, 2018 at 10:48 am, ajparent1/KB1GMX wrote: Yes, 2n2222A are an oldie. |
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Re: RF power chain mods and improvements..
>>Lowered the gain and the spur got worse?
As I have said, some of this can be counter-intuitive. There's a lot going on.<<< The weirdest I'd seen is as the audio drive came up the spur? would drop then rise and drop again before hitting the overload? point where a rise is expected.? ?At lower the voltage and that got better, but the gain was well below what was needed.? Lots of interaction.? ?First its VHF and transistors at low VHF are not so simple anymore as things like board and circuit parasitics get into the picture.? IF the beta is lower than predicted both gain and feedback are affected and the impedances at the ports? will deviate.? If the?HFE (DC gain) is at the edges the bias currents may wander out of? range and impact impedances at the ports.? ?The key is with three devices that interact there are many possible outcomes, some not so good. To that I insert Vonadas maxims.? I got to meet him at DEC?way back when.? While he applies them to computer design they apply to analog?stuff especially RF.? I made the applicable ones bold. Vonada's Engineering Maxims are a group of pithy observations about computer engineering?
compiled by Don Vonada, an engineer at DEC, and reproduced in:
? C. Gordon Bell, J. Craig Mudge, John. E. McNamara, "Computer Engineering"
?
They are:
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There is no such thing as ground.
Digital circuits are made from analog parts.
Prototype designs always work.
Asserted timing conditions are designed first; unasserted timing conditions are found later.
When all but one wire in a group of wires switch, that one will switch also.
When all but one gate in a module switches, that one will switch also.
Every little pico farad has a nano henry all its own.
Capacitors convert voltage glitches to current glitches (conservation of energy).
Interconnecting wires are probably transmission lines.
Synchronizing circuits may take forever to make a decision.
Worse-case tolerances never add - but when they do, they are found in the best customer's machine.
Diagnostics are highly efficient in finding solved problems.
Processing systems are only partially tested since it is impractical to simulate all possible machine states.
Murphy's Laws apply 95 percent of the time. The other 5 percent of the time is a coffee break.
I use LTspice and its a great tool however....? Modeling? and real circuits?may not match.? ?The quality of the device model elements count and then things like transformers are often modeled as "perfect" when the real part has a lot of little imperfections that might not be significant at 3mhz but may be significant at 45mhz.? Correlation is when the model is perfect and built units behave exactly the same.? I usually expect poor correlation (under 80%) until I've identified all the "strays".? The other is with models you can roll the dice and go Monte Carlo and introduce random variation in part values and performance to see if it is sensitive to variation. That last part if exercised enough is always informative. Allison |
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Re: IFshift
ok so im not trying to change the componet vavles im just trying to shift the if frequency a bit say 200 to 600 hz so it doesnt sound like a 1.8khz filter but more like a 2.2khz to a 2.4 khz filter i know its going to cut out the low end when i do this, but i have a very strong bass responce in the audio and want to cut it down a bit and bring up the mid and top end some
thanks ke4htb |
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