Keyboard Shortcuts
ctrl + shift + ? :
Show all keyboard shortcuts
ctrl + g :
Navigate to a group
ctrl + shift + f :
Find
ctrl + / :
Quick actions
esc to dismiss
Likes
- BITX20
- Messages
Search
|
Re: Small amp
Hello, I really appreciate Farman and Allison coming out to help. The main reason I want to increase my output is because I have to setup my antenna inside. It was pointed out that my walls will attenuate my signal, so I want to overcome that. I will check out the options laid out and will be a good ham and get a kit to filter my output (not that any one can hear me an way). I really want to operate qrp but it may not be possible considering my limits. Thanks again Farman and Allison, Chris |
|
You cannot design a crystal filter with the VNA, you can only test it to your design. To design a filter, measure the motional parameters of your crystals, probably the vna can help. Then, plug those values into one of the crystal filter design software and build it.? Now use the vna to test it with its S21 mode On Mon 6 Apr, 2020, 5:57 AM Curt via , <wb8yyy=[email protected]> wrote: Ashok |
|
Re: #v6 need a 12v connectiion
#v6
?Not all of those wall warts are regulated, as I found out. ?Need to test unloaded voltage against loaded voltage. ?Many 12 volt wall warts put out 16 or more volts at no load. This you do not want. ?Wayne WA2YNE On Fri, Apr 3, 2020, 12:41 PM Ion Petroianu, VA3NOI <ion.petroianu@...> wrote:
|
|
Re: Small amp
I have to fess up and admit that I am still new in the linear build process.? I bought a DIY Kit 70w SSB linear off of eBay for about $18 US.? With it, I also bought an XP-LPF-HF Filter kit for around $40 US (I cannot find the confirming email to get the exact price) two heatsinks and some spare parts.? It was a challenge to build because of the lack of clear instructions, the small size, the gap-filling that is needed to manufacture and install the two transformers, lack of an accurate schematic, and the fact that the bias circuit as delivered could not be adjusted correctly.? Coupled with my wanting to just get it to a stage to test, I had lots of issues to resolve.
The reason for bringing this up is that in another thread I stated that the finished linear did not meet FCC requirements.? Without going into the gruesome details, the final result is that the linear is delivering 50 watts with 4.5 watts in from my Hermes Light HL2 (I will get around to interface to my uBiTx).? It is compliant as measured with an RSP1 and version 1.04b of RSP Spectrum Analyzer.? This after destroying the original and one spare set of MOSFETs (IRF530), a relay, and a LOT of head-scratching and searching online for information. The main issues have been intermittent connections, a missing resistor to tame the input SWR, and a very touchy bias adjustment that ultimately required the circuit to be modified.? There are no clear directions on the kit, only documents that others have provided.? It was the bias adjustment that brought the rig into compliance after I corrected all of my bad connections and the input SWR issue.? Originally the bias was not able to reach 2.7 volts as delivered.? I had to add another 1k resistor in parallel with one of the original resistors to get the available bias adjustment above 2.35 volts (the value on the schematic was a range of 500 to 1K with 1K provided).? I then went the route of adjusting the bias the same way as the uBiTx (WRONG).? Could not get the standby current above 335 ma with 176 ma for the fan and relay board.? Left it at the max value to get in the "linear" region.? That was when I did the purity measurements and found it out of compliance.? I put it aside for a day and then went back and started adjusting the bias down from the 3.31 volts to see what would happen? ?The bias was last tweaked to 2.91 volts where the 2nd and 3rd harmonics disappeared into the noise of the RSP spectra. So if you are good at working things out for yourself from limited info, you have a steady hand at construction, and a junk box (or purchased spare parts) to cover the mistakes, then this is a good investment. For me, I learned a lot through this process and wound up with a new 50 watt rig for WSJT-X and other modes as a bonus! Based on the above, I must now change my recommendation and say that the linear and filter kit combination is a good buy.? I just wish there were better directions on how to set the bias and the construction overall. YMMV, it is not a kit for the light of heart,? and for sure do your homework before proceeding. 73 Evan AC9TU? ? |
|
Ashok
first of all, you did not specify SSB bandwidth or CW bandwidth.? Asshar describes design of SSB filter at 12 MHz on his BITX and uBITX circuit descriptions.? narrow CW filters are described on the web - they typically use 3 or 4 crystals each shunted to ground with a capacitor.? the capacitor value influences the exact bandwidth.? often one uses a frequency counter to match these crystals to 10 of 20 Hz - not as important for a SSB filter.? usually the principle is to employ crystals from the same manufacturing lot so they are similar.? the nice VNA is much more useful to measure the resulting filter.? there is a nice QEX article on crystal filter design available on the web.? let me know if you cannot find it.? Curt wb8yyy |
|
Re: Pretty Impressive
KN4SMO
Hi Richard, I am glad to hear that.? I can't wait. to finish mine radio. scott On Sat, Apr 4, 2020 at 11:10 PM R Blackman <richard.blackman@...> wrote: Today I made a solid SSB contact with ZD8SC in Ascension Island from Toronto Ontario on 17 meters. |
|
Having trouble locating files for Ver128.1
#bitx40help
I have a friend who has a Ver3 Bitx40 board.? It's been awhile since I've used Git Hub and can't find the
location to download Ver128.1.? I would appreciate it if someone could give me the link to the files so I? can forward it to him.? Thanks much es 73 de AG0H |
|
Re: S-Meter on Nextion Display
I just got mine s meter working, well kinda sorta. The s meter moves and the cw decoder sometimes decodes. It took me a few days to figure out the wiring, i didn¡¯t see this post till after been done.?
One part that confused me quite a bit was that all the diagrams i saw show the nextion on pins 5 and 6 on the raduino. Im pretty sure that on v6 with the 2.8 screen header the nextion hooks onto pins 5 (which you tap for the s meter) and pin 11 with the blue wire. That¡¯s how i had it hooked up before adding the s meter.? Also a4 and a5 on the raduino, i could not figure out if they come out to a pin on the board. The only thing i found was near q1 on the raduino, which seemed like dead ends with test points.? I ended up soldering header pins on the back of the raduino board were the header pins for the arduino are soldered.? I do like the way you mounted your s meter nano. Right now mine is hanging by wires, and i soldered the resistors and cap directly to it. I think this is a good excuse to try my hand at etching a board to mount the second nano and have the resistors and cap smd mounted.? Is there a specific way to figure out the numbers on the bitx manager. I put on there 4 at the lowest and 254 at the highest, then with the tool made is visually linear. The meter is responding, but i don¡¯t know how accurate.? and the cw decoder all it sees is e¡¯s and t¡¯s for the most part, even tho i was able to see some words get decoded earlier today.? I¡¯ll be checking this thread, because is the only one i found so far with the s meter on a v6.? Thank you luis ko4byi |
|
Re: Small amp
Okay
Before our expert designers get into it, let's not have global warming here. Okay when I saw wanting 2 bands, I thought ubitx not bitx. For the latter, the 10w qrplabs amplifier could be a good fit, do check to make sure you don't overdrive it, I imagine that is in the instructions.? 10 watts from 2 or 3 watts will be noticed, and later apply it to a qsx. Curt |
|
Re: My new V6 and what I learned from this group
On Tue, Mar 31, 2020 at 07:29 PM, McRuss wrote:
Thanks for the suggestions.? As for RF leakage, I'm in a situation where my dummy load is in a different state so can't do that.? I also have an issue with grounding since I'm in a condo with limited access to 'ground.'? But my other HF rigs seem to be OK with the same feed line.?If you have limited access to ground ,you might be successful with an 'Artificial Ground' It is a (variable)L ,(variable) C series resonant circuit with a sensitive mA or MicroA meter coupled to a toroid with the toroid sensing the current through the circuit . Connect one end of the circuit with the transceiver ground connection and the other circuit end? to a longest possible wire on the ground (possibly under the carpet ) At the operating frequency adjust L and C for maximum current as shown on the meter. It is advisable to make the sensitivity of the meter adjustable with a (front-operated)potmeter MFJ sell such a device . I have made one myself with the variable L being a roller inductor. The MFJ variable L is stepwise -switchable Ensure that the ground wire free end is properly insulated because there could be a HIGH RF VOLTAGE. Frank? , EI7KS |
|
Re: Small amp
allison, while the 6 db takes it only a single s unit, it does make a significant difference if you are hovering at the noise level. most of us QRPers are there. for casual operator on the other?end, it means a whole?difference between contact and no contact. - f On Mon, Apr 6, 2020 at 1:02 AM ajparent1/kb1gmx <kb1gmx@...> wrote: Chris, |
|
Re: Small amp
Chris,
Not sure what version of bitx but most of them were 3-10W? so whatever your getting now you want about 4x to make it worth your time. The other is you must respect input power for the amp purchased for 20W amps that means less than 2W input power some less. Allison --------------------------------- No direct email, it goes to bit bucket due address harvesting in groups.IO |
|
Re: Small amp
Hi all To clarify: QRP Labs has three amplifier kits, of which two have been mentioned in this discussion. All amplifiers should always be followed by adequate low pass filtering, at least sufficient to meet regulatory requirements. This applies to Linear as well as non-linear amplifiers, though linear amplifiers fed by a clean driver signal inherently generate low distortion so filtering requirements are generally less stringent.? The 10W Linear amplifier kit has high performance and good gain flatness +/-1dB from 160 to 10m. It also includes a pre-amplifier and should be driven with only 25-50mW to produce 10W output. It is designed for continuous key-down 10W. So for a non-continuous mode like SSB you could turn up the supply voltage a bit and get it up to around 20W.? The 10W Linear kit does not include low Pass filters but as has been pointed out QRP Labs has other kits which could be used for this.? The 50W amplifier kit is designed as a class C amplifier for the QCX CW transceiver kit . As others have pointed out, Class C isn't suitable for SSB and AM modes which require Linear operation. However, what has not been mentioned is that the class of the amplifier, in so far as the difference between A/B and a push-pull amplifier like the 50E amp, is merely a matter of which part of the transistor's curve the amplifier operates on: which is determined by the bias setting. Therefore the 50W PA could operate as a Linear amplifier if the bias trimmer potentiometer setting is raised (more clockwise) to produce an idle current, something like 1/4 A total would perhaps be appropriate but has not been tested here.? The 50W amp includes a single band low pass filter that can be built (with the supplied components) for 40, 30 or 20m. Other band filters would be possible using appropriate component values (L and C), or a switched LPF could be built for multi-band operation.? Both kits offer high performance, very low cost, and include the necessary heatsinks, PCB and all components. The 50W amp also has an optional enclosure.? 73 Hans G0UPL? ? |
|
Re: Hamstick Mag Mount
Sounds like a good, workable plan.
toggle quoted message
Show quoted text
Good luck, Ken, N2VIP On Apr 4, 2020, at 4:55 PM, Christopher Miller <djmalak2k6@...> wrote: |
to navigate to use esc to dismiss