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
Lol On Mon, Apr 6, 2020 at 4:09 AM Bill Cromwell <wrcromwell@...> wrote: Hi Chris, |
|
Re: Small amp
Hi Chris,
toggle quoted message
Show quoted text
After the first few replies I figured out that it was mis-stated in your original post. When I looked outside I noticed that the sky had not fallen and piece of it did not hit me on the head :) 73, Bill KU8H On 4/6/20 12:56 AM, Christopher Miller wrote:
I have a ubitx v3 sorry for the confusion. I¡¯ll probably use it on one or two bands any way. --
bark less - wag more |
|
Re: Small amp
Isn't it an option to increase (double) the voltage to the PA finals in the uBitx to increase the output power of the radio? Wouldn't that be an easier way to increase the output of the radio without building a small outboard linear?
toggle quoted message
Show quoted text
Ken, N2VIP On Apr 5, 2020, at 14:52, Ashhar Farhan <farhanbox@...> wrote: |
|
toggle quoted message
Show quoted text
|
|
Re: Small amp
I have a ubitx v3 sorry for the confusion. I¡¯ll probably use it on one or two bands any way.? On Sun, Apr 5, 2020 at 10:03 AM Bill Cromwell <wrcromwell@...> wrote: Hi, |
|
Re: Small amp
That reminds me of an ex gf. Her mother lived near a ham and I could copy cw from her tv. I don¡¯t plan on causing that kind of interference. Hopefully I can get a filter and amp for 20 and be done.? On Sun, Apr 5, 2020 at 9:36 PM STEVE via <behlmer=[email protected]> wrote: When I first fired up my ubitx 5w 40 m, my wife came down the stairs. She correctly accused me of wiping out her internet. It was the GFI. I installed a new one- no problem. Apparently newer ones are more resistant to RF. I bought a dozen. Some for me some for the neighbors. I¡¯ve still got nine of them.? !! |
|
Re: Small amp
When I first fired up my ubitx 5w 40 m, my wife came down the stairs. She correctly accused me of wiping out her internet. It was the GFI. I installed a new one- no problem. Apparently newer ones are more resistant to RF. I bought a dozen. Some for me some for the neighbors. I¡¯ve still got nine of them. !!
toggle quoted message
Show quoted text
Steve Behlmer On Apr 5, 2020, at 10:05 PM, Christopher Miller <djmalak2k6@...> wrote: |
|
Re: Small amp
I really don¡¯t think a 10-20 watt output with a hamstick dipole is going to produce rf burns. The last place I worked had a microwave that probably put out 1000 watts. You could open the door and it would start radiating. Somehow I didn¡¯t see it burning any one. I¡¯m going to have to double my output just to make this work. Chris? |
|
Re: #v6 need a 12v connectiion
#v6
Some of the wall warts seem to be DC regulated, but put out very large pulsating voltage.? They? generate all kinds of hum on receive and the transmitted signal looks very dirty on a spectrum analyzer. Ralph ku4pt On Sun, Apr 5, 2020 at 10:05 PM Wayne Leake <wayneleake@...> wrote:
|
|
Re: Small amp
You don't want to be able to transmit further than you can hear. If you are getting 10 db loss in signal transmitted outside the house you are probably getting a similar loss on the ability to hear others. |
|
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? ? |
_Dave_ AD0B
to navigate to use esc to dismiss