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mono band 2 meters rig based on the micro BITx circuit
#ubitx
#2meters
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my attention has turned to building a single band rig for 2 meters and I am curious who might also be interested in such a device.? my initial plan is to build the main circuit board the identical size of the uBITX and later reduce it to?within the confines of the common 20 by 4 line LCD character display.? in an attempt to build this as a Handi Talkie rig.?
-Justin N2TOH? |
开云体育I understand the motivation, but the Chinese are mass-producing dual band HTs for less than $30 delivered to your door, and the Japanese are producing higher-quality units starting at about $120, how much of a premium over these off-the-shelf solutions are you willing to pay to build your own VHF radio? Are you hoping for SSB operation or FM?Personally, I'd love to see an extremely simple version of the old Heathkit Two'er lunchbox that handles either SSB or AM on 2 Meters for under $40 all-in, as a fun club build, but I suspect I'm alone on that desire... I think it would be fun to have a local net based on low-cost radios and antennas so small no HOA could object to. Ken, N2VIP On Apr 26, 2018, at 3:44 PM, freefuel@... wrote:
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Steve Black
开云体育You are not alone. I would be glad to see a 6
meter or 2 meter or even dual band radio for AM or SSB or both.
It would be easy to conceal from the HOA people. A? small self
contained unit would be awesome. Steve kb1chu On 04/26/2018 05:00 PM, Ken Hansen
wrote:
I understand the motivation, but the Chinese are mass-producing dual band HTs for less than $30 delivered to your door, and the Japanese are producing higher-quality units starting at about $120, how much of a premium over these off-the-shelf solutions are you willing to pay to build your own VHF radio? Are you hoping for SSB operation or FM? |
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Hi Ken, the driving motivation here is for Single Side Band operations, with that said your totally and completely correct there is absolutely no financial benefit to building an FM only VHF circuit.?
with the 45MHz crystal filter I can see it maybe working on 4 Meters, 2 Meters, and maybe 1.25 Meters. so I could see a reasonable compromise being a dual band rig with 2 meters and the option of 4 meters or 222MHz.? for 6 meters I understand a different crystal filter would need to be employed.? -Justin N2OTH? |
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I wouldn't even care about AM. AM operation greatly increases the
complexity of thermal design. SSB would be all I would want - especially with a good receiver! tim ab0wr On Thu, 26 Apr 2018 16:00:38 -0500 "Ken Hansen" <ken@...> wrote: I understand the motivation, but the Chinese are mass-producing dual |
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for Ken and Steve, if you want compact antenni you really need to look into loop antenni, it's amazing what you can accomplish with some old Cable TV coax and an adjustable vacuum capacitor.? or soft copper tubing for that matter, some people have even managed to pass them off as "Lawn Art". I've even seen at least one example of a loop hidden under the table top of a plastic outdoor set.? with limited success there is the old standby of the rail gutters, and even the holiday lights for the creative!?
-Justin N2TOH? |
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Steve Black
开云体育I just buried 32 radials for a flagpole antenna I
am installing for HF. I have an MFJ loop antenna in my attic as
well as several vhf and uhf antennas. I have a camo tri-band for
2 meter 1.25 and 70 cm soon to be installed in an oak tree. If I
place it 30 feet above ground in the 65 foot tree my outdoor
antennas will be 130-135 ASL. My previous location was 30 feet
ASL with a 50 foot tower so with the HOA I am still 50 feet
higher. I had to sell the crossed Yagi antennas I used for space
stuff but I'll get over it. Oh I'm still planning to hide a wire
dipole or two. If you can't see it its not there! Steve kb1chu On 04/26/2018 09:37 PM,
freefuel@... wrote:
for Ken and Steve, if you want compact antenni you really need to look into loop antenni, it's amazing what you can accomplish with some old Cable TV coax and an adjustable vacuum capacitor.? or soft copper tubing for that matter, some people have even managed to pass them off as "Lawn Art". I've even seen at least one example of a loop hidden under the table top of a plastic outdoor set.? with limited success there is the old standby of the rail gutters, and even the holiday lights for the creative!? |
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I agree, only ssb/cw is all is needed. Keep the quality of TX of Ubitx increasing the average output like the MFJ ssb transceivers. Il 27/apr/2018 03:14, "Tim Gorman" <tgorman2@...> ha scritto: I wouldn't even care about AM. AM operation greatly increases the |
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A very thin copper wire supported by fishing line would be invisible. I had a 160M dipole supported at the centre like this for ages way back. I had actually used a length of very thin intercom cable and it was practically invisible.? So a very thin copper wire supported by a fishing line will be invisible. On Fri, Apr 27, 2018 at 5:34 AM, Steve Black via Groups.Io <kb1chu@...> wrote:
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I haven't ordered my uBITX yet, but I am very excited about the idea of a 2m SSB radio. I could probably only use it while in the States(summers), because I just don't think there'll be any activity where I'm at during the school year, but I would still love the idea of using it while traveling during the summers.
Scott N0SAB |
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Dave Bottom
I think it would be a great project. In the ‘60s I built a solid state 2M transverter and it only had 100mW output but I worked 500 miles regularly with my little Skelton slot antenna. A sad story that another Ham stole my 100W Motorola rig I was going to turn into a linear amplifier but a couple of hand held 2M SSB rigs would be a blast.
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I did build two 2M AM handhelds using the basic concept of the CQ Ham Tip rig (Superregen IF) and common audio for both RX/TX but with transistors (6 if I remember correctly). They were great for playing with VHF/UHF antennas while I waited for the opportunity to take the train to Customs House in San Francisco to take my General exam. Dave WI6R ex-WB6BDA On Apr 26, 2018, at 6:13 PM, Tim Gorman <tgorman2@...> wrote:
I wouldn't even care about AM. AM operation greatly increases the complexity of thermal design. SSB would be all I would want - especially with a good receiver! tim ab0wr On Thu, 26 Apr 2018 16:00:38 -0500 "Ken Hansen" <ken@...> wrote: I understand the motivation, but the Chinese are mass-producing dual |
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For 6 and 2m SSB use it is a great staring point.? The power amp stages are not up to it for 2
at all but for 6 with work it can be made to work.? ? For the RX side you need a good LNA on 6 and 2.? For 6 a gain of 10-17 db is enough. For 2M the gain will need to be closer to 20Db and the noise figure under 1 db. To do dual band you need two front ends (LNAs) and switching from those to the 1st mixer.? Same for the power out stages as wide band in that range is tougher to do than a per band stages.? ? A target power of 10W is adequate 20 would be better. For 4M we don't have that band here but that is about the same story as 6M however its going to need a better power amp.? The IRF510 can pump power thee but everything before it has hit the wall at 10M and needs better devices to go higher.? UHF with ubitx its better to use it as an IF with a transverter. As to VHF loop antennas, forget the Vacuum variable. its not needed.? For 6M the loop is about 30 inches across and the end gap tunes it.? For 2M about 11inches and the end gap tunes that.? For VHF height is valuable but also makes it hard to hide.? Gama fed in both cases.? Use good coax (quality RG8X minimum for short (under 25ft) runs as losses are painful.? For longer runs RG8 .400 cable (RG213 or LMR400) are the usual. However if you can do a beam (easy on 2M due to small size for a 4 element) it really helps.? Staced loops also help but the stacking distance for 6m is around 12Ft and for 2M 4ft so its not stealth. NOTES: Around here in Eastern MA USA getting higher than the trees is the trick as they absorb a lot.? ?That is rarely stealth.? Second best is higher?than buildings.? ?Dead last is in the attic, roofing material especially wet are absorbers.? Indoors works for local to a few miles at best.??I run 6M ssb from the mobile with a square loop onthe truck using a HB rig at 4W or I add in the 6M brick I built?to pump that up to about 70W.? The home station the usual rig is HB contest radio for 6M (about 7W),? Tentec 6n2 (20W), and FT817 for? 432mhz.? Matching HB amps to get to 160W on 6,? 160W on 2, and 60W on 432.? Antennas see QRZ, I have 5 elements on 6M,?11 elements for 2M and 15 for 432.? All are my design or highly modified commercial. I also have antennas for Field Day (last full weekend in June) for 6/2/432 that are somewhat portable.? Mountain (or high local hills) topping works using simple beams or loops.? Be aware unlike HF polarisation counts, for SSB (VHF AND UHF) its generally horizontal here, the islands, and from all accounts in Europe. cross polarization of direct local links incur great losses ( sometimes more than 20DB). I've been on VHF and up for a long time and built for all of the bands including 432 (transverter to 10M). It is more home to me than HF. Allison |
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On 2018-04-26 22:33, freefuel@... wrote:
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I haven't really been following all the details of the conversation, but how about a front end mixer to convert VHF to HF? You'd still need to work out something for FM but most other modes would be covered. ? Sent from Yahoo Mail. On Friday, April 27, 2018 5:11 PM, Tim - M0THM <tim@...> wrote: 4 and 2m ssb would certainly grab my eye.
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On 2018-04-26 22:33, freefuel@... wrote:
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开云体育If this new 2 meter radio would be used on FM… it’s time to start over.? Most of the IF chain will have to be modified to work including the crystal filters and addition of a discriminator…. And a way to frequency modulate the oscillator on transmit.? Way too much work to perform on a uBITx.? Start over from scratch. ? ? Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ ? Owner - Operator Big Signal Ranch – K9ZC Staunton, Illinois ? Owner – Operator Villa Grand Piton – J68HZ Soufriere, St. Lucia W.I. Rent it: Like us on Facebook! ? Moderator – North American QRO Group at Groups.IO. ? email:? bill@... ? ? From: [email protected] [mailto:[email protected]] On Behalf Of Thomas Sharka via Groups.Io
Sent: Friday, April 27, 2018 4:50 PM To: [email protected] Subject: Re: [BITX20] mono band 2 meters rig based on the micro BITx circuit #ubitx #2meters ? I haven't really been following all the details of the conversation, but how about a front end mixer to convert VHF to HF? You'd still need to work out something for FM but most other modes would be covered. ? ? ? Sent from Yahoo Mail. ? On Friday, April 27, 2018 5:11 PM, Tim - M0THM <tim@...> wrote: ? 4 and 2m ssb would certainly grab my eye. ? ? On 2018-04-26 22:33, freefuel@... wrote:
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Makes sense the transverter approach. Not sure whether the ones from Ukraine could match well. But is a different approach. You need both hf and transverter. This may give some advantages? but is not very handy for sota or portable operation. Il 27/apr/2018 23:49, "Thomas Sharka via Groups.Io" <sharkatw=[email protected]> ha scritto:
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Several things, like others have repeatedly pointed out the uBITX is very unsuited for FM or AM.
FM needs wider filter and far more gain to get the needed limiting action.? Its not drop in its full replacement.? A Baofeng UV5R goes for 30 bucks and does 2M and 70CM.? ??AM there are issues with drive level and sustained power out, that and its sparsely used.? My opinion is that if you want all that get a FT817, its a do all and has a noise blanker. To get the front end to cover VHF the LO system deliver a VHF LO (95mhz for 6M, about 99 or 189mhz for 2m) and the input filter needs to pass the VHF band and not a low pass.? IF memory sers the 5351 can go to 220Mhz A LNA before the mixer would be required for reasonable performance.? ? For UHF if you had a version of the 5351 or maybe used a si570 flavor to generate the LO and an improved mixer 432 is possible but its more effort and would likely need a board redesign. UHF is better done with a competent converter/transverter with a 404mhz LO and run that into a uBitx at 28mhz. In all cases 6 though 70cm the tx power chain would need work as the drivers are all 300mhz FT devices? just will not do it.? ?The IRF510 I've used at 50mhz as a monoband linear and its respectable (40+W for push pull @ 28V properly done for 6M only) but I think maybe 70mhz is a stretch without first trying.? In all cases the TX chain is mono band only as VHF impedance matching from stage to stage is required. Just dropping in higher FT devices will not help its a across the board redesign for a specific band. Receiving is easy enough, transmit above 50mhz is going to be harder. Allison |
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Allison, For a power chain of about 5 watts that goes from 50 mhz to 500 mhz, what would be your recommendations? The RD15HVF1 seems to be used frequently at 435 Mhz. Are there any broadband alternatives? What kind of cores can we use at UHF?? - f On Sat, 28 Apr 2018, 06:37 ajparent1/KB1GMX, <kb1gmx@...> wrote: Several things, like others have repeatedly pointed out the uBITX is very unsuited for FM or AM. |
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Respectfully, as Allison points out, it's not just the PA active element
that will be the problem. When your frequency width is an order of magnitude, e.g. 14Mhz to 144Mhz, you begin to run into all kinds of issues with components. Lead lengths and circuit trace lengths/widths at 2m cause many more problems than at 14Mhz. It gets even worse at 432Mhz. I agree with others on here. It would be a lot more feasible to do one band modules, e.g. one for 2m and another one for 432Mhz, that are small enough they could be placed in one case along with a ubitx being used as an IF amplifier. tim ab0wr On Sat, 28 Apr 2018 01:12:16 +0000 "Ashhar Farhan" <farhanbox@...> wrote: Allison, |
Scott Bridges
K9HZ
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