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Ubitx - Increased voltage to finals thru middle wire on power plug...no effect
Kevin Rea
hi guys,
I thought i would try a little experiment. I was running 12 volts on the dot to the middle wire on the power plug on my v4 ubitx and the output is about 16 watts on 20 meters cw. I then increased it to 23 volts, and the output was the same, about 16 watts on 20 meters cw. I thought there was going to be some increase ? Here are a couple shots.. kevin rea lancaster, calif. k6rea |
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Re: Modular uBitx - "Ex: Harmonics"
Allison Agreed.? Some readers have an aversion to installing a PC level board inside a radio. I can understand, but also see the need to try it with one of the tiny but full featured PC cards like the Raspberry Pi or Pi-Zero.? That could allow any of the Linux applications (fldigi, etc.) to exist and run inside something like the Ubitx or one of the QRP-Labs creations.? Using I2C and a Nextion display could provide bus-level interfaces for many plug-in functions.? USB could host the mouse and keyboard to make a very compact rig for field-day activities.? Shielding for such a small PC board becomes less of a problem with these small boards.? I don't have the time, but maybe someone will take on the challenge. Arv _._ On Thu, Aug 16, 2018 at 7:03 PM ajparent1/KB1GMX <kb1gmx@...> wrote: Arv, |
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new build
Hi Y'all;? I'm Reuben Titus, N4ISF. Middle TN. ? A friend told me about the uBitx so I ordered one yesterday. Figure I will try it for home/portable/mobile,? maybe tie in a tube amp for home use, maybe build me a solid state amp for portable if the power source is good for it,? or not if it's limited to a small battery. ? I have a Heathkit 80-100 watt all tube transmitter I started with as novice around 1980 if it still works, (it was old then)? it was an AM-CW only unit but could do SSB with external signal input. ? As original it had a drifty tube VFO with crystal option, and the HQ145X receiver that I used was very drifty as well. ? ? Most of my electronics education was early 80's style on back,? the 1982 ARRL amateur handbook was my reference book,? I wore it out and still use it. Spent a lot of time with the QST magazine issues from the 1930's to 80's that I found in a library.? ?? Haven't kept up with modern stuff very well,? but I can try.? And I've been foolin with various things over the years and picked up enough test equipment to play with stuff a little, oscilloscope,? capacitance/inductance meter, signal generators, ? etc.? Mostly doing stuff like weird versions of brushless DC motors, making my own electric fence chargers and electronic ignitions for old vehicles,? etc. ?? So. ? New project to get me a working transceiver again.? The kenwood TS820 I have started having issues a while back so I've been thinking of finding something else, something I can carry around and mess with easier. ? The 820 likes to stay put (heavy) and the interior is so packed it looks like a challenge to fix. And a bigger challenge to figure out why it's doing what it's doing,? throwing in excessive interference on the received signal and kicking the digital readout off at the same time.? ? Think I'll put it on ebay sooner or later,? it might sell for enough to recover the cost of the uBitx. since I see a nonworking one on there now that's bid to over $100. -- N4ISF |
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ubitx troubleshooting help - low power after irf510 replacement
I have a bit too much experience with cooking the finals on my ubitx...I'm on about my fourth or fifth set of IRF510s.? I think that I'm probably overdriving too much on digital modes...but here's the question After the last replacement and re-biasing of the PAs using the standard +100 mA per pot technique, I found that I had decent power on 40m, but had virtually no output on 20m or 17m (where I'd previously seen at least a few watts out). so...here's my question: did I perhaps damage something other than the irf510s, or do I perhaps have bad irf510s (these were from a different batch)?? I have an oscilloscope and a dvm, but not really 100% sure how to proceed.? I had an idea that I might want to put on a dummy load, use the wsjt-x 'tune' function (with a relatively low drive setting) and then measure at different points, but I'm fairly new to electronics and not sure enough what I'd be looking for. I was thinking perhaps checking each amplification stage, but would need some advice on what to look for. Ideas??? Thanks! Sean |
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Re: Sunday
I get 7w with a class E NS40 by 4sqrp. Apart from the layout of the board, a real masterpiece, it is amazing that just after key down the final remains that cold (very mild temp). My other twofer qrp by Hendricks with just 1w the final notwithstanding is biased correctly is hot. Thumbs up for class E... a pity there is no commercial class E amplifier as far as I now. Il 16/ago/2018 18:40, "Daniel Conklin" <danconklin2@...> ha scritto: Jack, I'm getting about 4 watts output with 13.8v the way I have it currently configured. It's driven with a 2n7000 MOSFET. I'm wondering if the uBiTX could benefit from this because it requires lower drive levels from the LO.? |
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Re: Harmonic performance - SSB vs CW
Those digi modes are done with a set of tones to your radio and use SSB - NOT CW.
toggle quoted message
Show quoted text
73, Bill KU8H On 08/15/2018 06:32 PM, peder@... wrote:
Could you do a run on Digital? We have a group planning on using this --
bark less - wag more |
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BITX QSO Afternoon/Evening, Sunday, August 19, 3PM & 7PM Local Time, 7277 kHz in North America, 7177 kHz elsewhere.
John P
BITX QSO Afternoon/Evening, Sunday, August 19, 3PM & 7PM Local Time, 7277 kHz in North America, 7177 kHz elsewhere.
Join us as we make contacts with our BitX-40s or uBitXs or anything else on 7.277 MHz in 40 meters! This is a worldwide event for BitX40 (and other QRP)?stations starting at 3PM and 7pm in each time zone. To participate, call CQ BitX on Sunday, starting at?3PM and/or 7PM?your local time. The BitX QSO Night continues through the evening and conditions usually improve after sunset, so it is worthwhile to participate later in the evening. Suggested Best Operating Practices: Work at QRP power levels unless conditions require more power. Report your QSO's, discuss propagation, noise, signal reports, audio reports, antenna type, etc. in this thread. This is an undirected, scheduled event.? The BITX QSO Night relies on you to call CQ BITX to initiate contacts with other stations, so warm up that final and transmit a few calls on Sunday evening.? Talk to you then! |
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Re: Modular uBitx - "Ex: Harmonics"
W2CTX Interesting thought.?? We already live with noise from the AVR/Arduino on 16 MHz, 12 MHz, harmonics of these, and mixed products of those.? Yes, putting any computing device inside the radio chassis will cause problems.? It is a trade-off for convenience and functionality versus having a quiet receiver.? Of course if we really want a very quiet receiver we would not be using double conversion.? Direct-conversion with phase shift methodology replacing filters could eliminate much of the mixing products of a dual-conversion architecture.? This does bring up the idea of having a chassis-within-a-chassis to shield the radio from computer or computer from the radio.? Heating/cooling could be problematic, but not insurmountable.? Arv _._ On Thu, Aug 16, 2018 at 2:19 PM W2CTX <w2ctx@...> wrote:
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Re: Modular uBitx - "Ex: Harmonics"
Eric Flores
No one concerned with extra power draw or noise generated by the pi? Some people might be concerned about, others may want the RPi so much that they compensate for it. With the suggestion of putting the?Si5351 on the mainboard, it would leave options open for the end user. On Thu, Aug 16, 2018 at 3:19 PM W2CTX <w2ctx@...> wrote:
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Re: Modular uBitx - "Ex: Harmonics"
No one concerned with extra power draw or noise generated by the pi? On August 16, 2018 at 4:12 PM Eric Flores <floreseric1981@...> wrote: |
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Re: Modular uBitx - "Ex: Harmonics"
Eric Flores
One of the Rasbberry Pi versions could probably be added inside a transceiver case running Linux.? That could replace an Arduino and PC as well.?? I liked the suggestion from RCBoatGuy that pertains to this: - Si5351 on main board, not on Raduino/Teensyduino/JackAl If the?Si5351 was on the mainboard, then you can use whatever you want for the CPU board and the it via the I2C interface. It would increase the hackable-ness of the uBitx. Eric On Thu, Aug 16, 2018 at 1:04 PM Arv Evans <arvid.evans@...> wrote:
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Re: Sunday
Dan,
No as ubitx for SSB requires a linear amplifier. The AM class E I have for 160 (IRFz24s) does easy 20W carrier 100% modulated its near 80w.? Efficiency is north of 80%.? I've been called peanut-whistle with that. One of the locals has a full legal limit AM for 160 class E modulated with bridged class D.? Broadcast class audio and 375watts carrier. Broadcast band AM went this way years ago, saves money for the power! For AM/CW its the way to go. Allison |
Nick VK4PP
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