How much $ to get into SW with more then 5 watts Tx? - Page 1
Forum section: electronics / rf-microwave

author: Beamin
author_rank: Super Contributor
timestamp: October 12, 2018, 11:51:50 pm
content: I now live in a house where I can run a wire antenna out the window with a grounding rod, maybe even a small vertical. I had a good antenna before but with only 5 watts it was frustrating only making 0.5 contacts I was keyed over. So how much for 100 watts since it seems like all the guys I hear have 100 watts.Can I use my Walmart brand CB SWR to measure down to 7mhz? Whats a good band/compromise on size? I have probably 50 from the 2nd story window to the end of the back yard possibly tying the end to an arrow and sacrificing and arrow to get it up in the tree. I have made 45' antennas from 2nd story to a tree before.I will need (cost)?:Used HF Radio maybe a chinesium if they make one yet?SWR meter maybeAntenna tuner maybe, or is it just necessary when you want to make magnetic loops in small spaces? I know an ideal set up would have one but won't my radio be able to tune to a wire antenna that cuts specifically for the band? How much can you compensate for or do you only get 1/4 1/2 and full wavelengths because length is too critical?Power supply, this could be a fun build if I can get a step down off the internet that can handle it. Do you need 13.8V can you go 14V or 12V? Can a bridge rectifier and filtering caps make clean enough power for it? Could you bridge a bunch of ATX with the resistor/greenwire mod to work together? ATX power supplies are almost free if you find a computer recycler.Misc bits to connect the antennaRG6 50 ohmsCopper pipe to pound into the groundWire for ground or even 75 ohm coax if that will keep the ground from picking up noise as I have tons of the stuff.Have:Leveel 7 Microsoft techneecian class lic (Do one thing: With left hand. Press the window key and with your same hand press R as in Rohit Gupta)Some antenna connectorsA bunch of time and creativityAudiophile grade power conditioned 120 VAC from roof mounted solar panels if it's sunny out. Speaking of which I haven't played my with my SDR to test, as it sucks without a mouse, will the inverter fuck up reception? Seems like a reputable company but looking outside the inverter might be in the basement because the box on the side of the house is generic looking and not high tech like most I have seen. I think they are newer ones though.I'm poor but going to sell some of my stuff to buy it. This or buy a drone, I have the FPV goggles and nice 10? channel radio chargers etc. But no drone the one I bought sucked. Hmmmm… I honestly just thought of that. A drone would be really cool wish I could rent one to see if its as fun as model air planes.

author: vk3yedotcom
author_rank: Frequent Contributor
timestamp: October 13, 2018, 12:02:44 am
content: Many questions but to answer a few:1. Yes a CB type SWR meter will work on 7 MHz. But it might be insensitive with low power.2. 7 MHz is the easiest band to get contacts on.3. 12 to 14v will power most rigs - it doesn't have to be exactly 13.8v. A 100w transceiver will require a 20 - 25 amp supply.4. It is possible to have a lot of success with 5 watts - whether you use CW, digital modes or SSB. But 100w is highly desirable for contacts about about 2000km. But you need to be on the right band and at the right time.5. A simple horizontal dipole (10m per side) is a trouble-free antenna for 7 MHz. Verticals are dependent on a good ground but are good for long distance stuff.6. There are low cost rigs that put out more than 5w. An example is the Bitx for 7 MHz or the uBitx for HF bands. Both require a little work to set up. Morse code rigs are cheaper.7. The US Technician grade licence is good for morse code operation on 7 MHz. It's also fine for 28 MHz SSB. But otherwise it's very limiting if you want to talk or do digital modes. For that a General is good.More details in articles, videos and books linked fromhttp://home.alphalink.com.au/~parkerp/gateway.htm&http://home.alphalink.com.au/~parkerp/qrp.htm

author: Nusa
author_rank: Super Contributor
timestamp: October 13, 2018, 01:06:36 am
content: Well, if you can endure Microsoft certification of any kind, you certainly can get the proper license for what you want to do:http://www.arrl.org/getting-licensedThe tests aren't hard, if you learn the material. And you'll answer many of the questions you've asked or want to ask by doing so.

author: Beamin
author_rank: Super Contributor
timestamp: October 13, 2018, 02:13:23 am
content: Quote from: vk3yedotcom on October 13, 2018, 12:02:44 amI have a bitx 7mhz. I think my SWR might have been a factor. It was a really good home made antenna cut for around 40m with a balun. But I didn't have a SWR meter so I could have been 3:1? Could be this far off if you are at a multiple of 40m in length? But I'm now realizing I might have been using 75 ohm coax. One time I knocked the radio over and it wedged itself in a way it was continually transmitting into this antenna set up for hours. My home built power supply was warm (Used am LM317 to regulate voltage) but not hot enough to soften hot glue on the heat sinks. I didn't smell any burning or even melted plastic around the bitX transistor. Works great on receive. Guys on 100 watts that I can hear fine in Florida or New England running 100 watts couldn't hear me I'm closer to new England but still in the middle. Even when I tried closer contacts they couldn't hear me. If you are running 100 are you not set up to hear DX/QSL? I know that varies from person to person's set up but in practice do you just talk to other high quality signals and let the others fall into the noise unintentionally keying over them?I have had that antenna on receive pick up india and everything but 'stralia but TX is a different beast. India has really cool news so different from ours about growing crops/ farming survival stuff kind of like old soviet broadcasts. "Did you hear the new Bollywood cheating celebrity scandal on the news? No but wheat production is up 3.7% to 8000 hectares or 2.5 mil bushels!"Is there a way to measure that the bitx is working? I turned the bias or gain up inside old CB radios to get more then 4 watts and the transmitters would just slowly fade away until no one can hear you. Would this do that? Mind you I don't have a known working antenna and only a 27 mhz "CB" SWR. Would it work at low power?

author: xaxaxa
author_rank: Regular Contributor
timestamp: October 13, 2018, 02:53:25 am
content: For 100W forget about 13.8V. All modern LDMOS power amplifiers use 26/28V or 50V. Older bipolar amplifiers are inefficient and ex🅱️ensive.

author: vk6zgo
author_rank: Super Contributor
timestamp: October 13, 2018, 04:25:17 am
content: Beamin, what kind of Amateur licence do you have, precisely?Re the CB type SWR meter---yes, they usually work OK at lower HF frequencies, & some are good up to VHF.One problem with using the one I have, is that it becomes more sensitive with lower frequencies, so you need to reduce power till you are not going over scale in the "forward "position of the switch.Some "CB" SWR meters are better than others.The scabby little one I have was bought as a "faulty return" at a CB shop, 30 plus years ago.It had no fault, & still works.On the other hand, the much more "up market" one I bought some years later, (along with a secondhand SSB CB), didn't work over much more than the CB band, & not brilliantly, even there.A tuned antenna is always easier to use than a random one, everything else being equal.A half wave dipole for 7.100MHz will be about 66 ft long, which is a bit of a hassle, but you can droop the ends, or even bend them to each side, or drop them down at an angle.Australian "Foundation" licences are limited to 5 watts, although they do have more bands, but they can make, & many have made, "DX" contacts.vk3yedotcom is very knowledgeable on low power operation, so click on his link, or just google for vk3ye.I would also point you to QRZ.com, which is a "ham" forum, with many members who will be able to point you in the right direction.https://forums.qrz.com/index.phpDouse your call sign, though, as people who sound like "pirates" will get short shrift.

author: Beamin
author_rank: Super Contributor
timestamp: October 13, 2018, 12:27:22 pm
content: Quote from: vk6zgo on October 13, 2018, 04:25:17 amIts a general class in the united states I got when I was young and kept up with it. I don't post my call sign because then you a are a few google searches away from finding my address and old male name/ info, I don't want the world/employers etc to know I used to be male or I am trans. I worked too hard to change how I look/ am. You can easily connect the dots to figure out he and she are the same person. I wish you could call these companies and say stop posting my personal info. Ridiculous we have a law protecting the companies rights but not the people.As for the SWR meters its that common 30$ one from Walmart.com you get off amazon. I guess with test equipment if it's not working you don't know and chase down ghost faults. I once had a calculator in school that gave random numbers when you pressed = . Since you were rounding decimal points it looked real. Luckily I argued with the teacher on my math test and we saw the random numbers on the screen. I always thought it would just stop working never seen a fault like that.How can you tell that the meter is not working rather then the equipment if you only have one thing to test? I wish I had the money or I could find those MFJ ones like in kevin loughlins videos with the $30.00 price tag not 299 retail.Without a SWR the only option is buy a commercial antenna and even then that's still not a good idea right? So its as important as my power supply?

author: vk6zgo
author_rank: Super Contributor
timestamp: October 13, 2018, 04:01:43 pm
content: Beamin, I know a ham in a similar situation to yourself, who maintains their old call sign, & seems to have had no negative repercussions whatever.If you have been inactive for many years, time & lousy memories will have blurred people's identification of you, anyway.If you change your call sign, I think you can have your address recorded as a simple PO Box number, so people will not make the connection.OK, the FCC will know,but they know already!After all, your sexual identity is your business, & you will be surprised how few people give a damn.I am lazy, so use my call sign as my nickname on a number of sites, on some of which, I argue about politics, sport, electronics, & ham radio.Other people do the same, some of which, I have had fairly heated arguments with, but it stays on the website.In my country, it is illegal for an employer to discriminate against you on the basis of race, religion, political beliefs, sexual identity, what football team you follow, whether you like Tektronix or HP, or whatever, so that, if they ever did ferret out my identity, they couldn't do anything, anyway.OK, I'm retired now, so even if they could do anything, it wouldn't affect me.As to the SWR meter, my old one was probably no better than the Walmart one.With 5 watts available out of your radio, you could make up a 50 ohm load out of resistors, perhaps in series parallel to give you good margin of power capability.This will give you a calibration point at an SWR of 1.1:1.If you make another at 75 ohms, that will give you a 1.5:1 calibration.That will allow you to check the meter's calibration.If you want to, you can make a number of these calibration loads by calculating what different values of R will give you.This will allow you to draw up a correction sheet.I Googled for SWR calculators, some don't seem to work with the iPad, so they may be dead, or maybe they just don't speak Safari.This one worked OK:-http://www.typnet.net/AJ4CO/Calculators/Impedance_Mismatch_Loss_and_SWR.htm

author: Nusa
author_rank: Super Contributor
timestamp: October 13, 2018, 04:07:00 pm
content: Your Microsoft license joke gave the strong impression that you were transmitting without a license. Glad to hear otherwise. How do you avoid your identification concerns when actually using your callsign?

author: Beamin
author_rank: Super Contributor
timestamp: October 15, 2018, 01:27:08 am
content: Quote from: Nusa on October 13, 2018, 04:07:00 pmI always use in on air you have to I'm a stickler for those rules and like to keep the air pure so it doesn't turn into CB. I just do not use it on the internet where google picks it up. If I make contact with one of you guys on DX I'll tell you I'm beamin with my call sign, that would be nice but unlikely unless we tried to set up a contact. I'm not worried about fellow hams getting my call sign its just weird people on forums. One time I was talking politics on a car forum. I was lax with my info as I indirectly did business with one of the members. This pile of shit who I thought was 14 years started writing bad reviews and calling the business because I "owned/pwnd" him on the internet. I had to cut into my workday to avoid the damage that really could have cost us business as a small company. Turns out he was 65 and also started calling the university another member taught at trying to get him fired. He was some idiot neocon that would try to debate.

author: Wirehead
author_rank: Regular Contributor
timestamp: October 15, 2018, 05:26:35 am
content: If you only have 5W avail, try to minimize losses:-Try and get some RG213 in stead of using RG6; Shouldn't cost too much and plenty to find around hamfests. Some friendly hams might just give some length to you-Try and use monoband, efficient dipoles; with a current choke/balun right at the feed point of the antenna. It "forces" RF out the antenna, in stead of making the outer shield of your coax radiate (thus getting more QRM / RF "in the shack"). It's cheap, it's made with bits and bobs laying around. Want multiband? Make it a fan dipole. Bit trickier to adjust.-5W isn't much at this moment of the solar cycle. Try FT8; you'll be amazed what you can do with 5W-The Yaesu Ft-450 (Be it the -AT or -D variant) can be found for little money and has a tuner on-board. 100W out. Be wary of tuners in the rig. It's there to protect the transceiver. You could still have a horrible match on the coax, and thus be losing lots of power. Tuning at the antenna itself, or having nicely resonant antenna's, is way better. Bonus of the FT-450: very easy to retrofit a second RX to feed into an SDR receiver.

author: HB9EVI
author_rank: Frequent Contributor
timestamp: October 15, 2018, 06:50:37 am
content: When I started as ham operator, I ran only qrp with an FT817 but with a good success.The trick, I guess, is minimizing the loss of the system, so:- watch out for well matched antenna setups. Many ops continue running tuners in the shack - with a coax line to the antenna, what is a no-go you realize when calculating the losses on the feedline. Doing so with 5W will certainly not be fun to reach DX.- if you have to run long cables, it really makes sense to go for a better one than a common RG58; instead of a bulky RG213 you can go with an Aircell 7 of similar properties to the RG213, but lighter and more flexible.- depending on the qth, you have to choose operating frequencies. Working 80m or even 160m with a 6,3m vertical is rather challenging - it still might work, but surely not on the same level like 20m. Compromises have to be done.- IMO don't go for a chinese rig. Afaik there aren't yet any 100W rigs, and the qrp rigs all have some more or less nasty issues. It should not be a big problem to get a used Y/I/K 100W shortwave rig on the market for little money; recently many ops threw out their rigs in favor of an IC-7300. My guess'd be that you could get e.g. a TS-50, a FT857 or an IC-706 for 200 bucks or less.And don't except too much from a CB swr-meter on the lower ham frequencies; mostly these are stripline bridges which have not enough coupling below ~25MHz.You can easily rebuild such a CB meter to work well on ham frequencies, use two ferrite toroids and build a Stockton coupler and you're ready to go

author: Beamin
author_rank: Super Contributor
timestamp: October 15, 2018, 07:12:44 am
content: Quote from: HB9EVI on October 15, 2018, 06:50:37 am200 bucks is definitely in the budget. that leaves me money for an SWR meter too! This cable will be short going to the window of the bedroom. When I was running 75 ohm then to a balaun at the base of the long wire would that give my five watt tx problems maybe permanent transistor damage?

author: CJay
author_rank: Super Contributor
timestamp: October 15, 2018, 11:11:03 am
content: Quote from: Beamin on October 15, 2018, 07:12:44 amIt's not available yet but perhaps the QSX from QRP Labs might be of interest...https://qrp-labs.com/qsx.html

author: HB9EVI
author_rank: Frequent Contributor
timestamp: October 15, 2018, 02:28:10 pm
content: Running shortwave over a 75 ohm cable or into an antenna with a real 75 ohm impedance is absolutely of no concern to any transceiver, hence it equals to a SWR of 1,5:1.All modern solidstate transceivers reduce output power if the mismatch is getting too high; some are strikter than others and start reducing already at 2:1 while others start first well over that mark.It's an urban legend that your PA burns through due to a too high SWR.

author: bd139
author_rank: Super Contributor
timestamp: October 15, 2018, 02:48:04 pm
content: Not necessarily. Some of the earlier FT-817's blew up if you had high VSWR hence the ubiquity of the replacement PA modules.1.5:1 is nothing to worry about though.

author: HB9EVI
author_rank: Frequent Contributor
timestamp: October 15, 2018, 03:17:36 pm
content: the non-ND 817 finals mostly died of self oscillation due to low operating voltage, what was rather surprising since it came with a 8 cell nimh-pack with a nominal 9,6V

author: bd139
author_rank: Super Contributor
timestamp: October 15, 2018, 03:26:50 pm
content: Yeah that failure mode was certainly a bit of naff design

author: coppercone2
author_rank: Super Contributor
timestamp: October 15, 2018, 05:52:42 pm
content: What kind of power circuits do modern commercial rf transmit circuits use for their power rails?Are they linear or can you economically filter power rails of commercial supplies (i.e.48v telecom) to meet the FCC specification and use something like a meanwell unit?

author: HB9EVI
author_rank: Frequent Contributor
timestamp: October 15, 2018, 06:14:09 pm
content: 28V and higherthere are some ham PAs for 2m and 70cm based on refurbished MRF186 available, which runs at 28V and was extensively used in the 900MHz mobile band. Most contemporary FETs in lateral construction run from 48V

author: coppercone2
author_rank: Super Contributor
timestamp: October 15, 2018, 06:33:41 pm
content: I meant more along the lines of what is the PSRR of a common RF amplifier topology, so the rail supply can be chosen.