Re: Should I wait to buy a ubitx?
If it bothers you so much, I think you, yourself, should suspend buying one and go buy a Yeasu or Kenwood or Icom or maybe even a Baofeng!
Vince - K8ZW.
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On 03/11/2019 01:21 PM, Bill Harris - K5MIL wrote: I think they should suspend sales until they can finally get it right
and produce a unit that you don't have to mod to high heaven to make it
work properly.
Bill - K5MIL
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K8ZW
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Re: AGC Pre-Oders are in and built!
Amazing! I imagine you do brain surgery on the weekends (grin) Steady hand. I used to be able to do smd however now I would probably sneeze and blow the whole pile of boards and parts bin right off the table!?
Very nice work!
Jim
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I have Axicom relays installed because it was ver. 3 and it was really needed. Ver. 5 is greatly improved and, according to the advertising, should be fine. If you replace them with Axicom you should not go any wrong. But if you feel confident to remove them. I found it difficult, honestly. Another ham said it would have been easy if I had used a wet wood toothpick to remove the excess of solder in the holes.
Il 11/mar/2019 18:08, < Jscook@...> ha scritto: Just received what I assume is a Ver 5 mother board , shows 06 19 stenciled on board, and it has HFD27/012-S relays. Should these be changed to axicom relays?
Jim
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Thank you, Curt!? ?It's actually a very nice construction document.? Based on that, it wouldn't be too hard to make into a kit.
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On Mon, Mar 11, 2019 at 09:03 AM, Curt wrote:
https://qsl.net/nf4rc/2018/OutboardRelaysDesignDocumentTry3.pdf
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Re: Should I wait to buy a ubitx?
I think they should suspend sales until they can finally get it right and produce a unit that you don't have to mod to high heaven to make it work properly.?
Bill - K5MIL
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Just received what I assume is a Ver 5 mother board , shows 06 19 stenciled on board, and it has HFD27/012-S relays. Should these be changed to axicom relays?
Jim
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Re: Ordered my v5 ubitx today, case delivery tomorrow!
I was shocked at the speed the case was delivered . Ordered it Thursday and it arrived today.? ?That's as fast as Amazon and it came from India!
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Re: Spurs and Harmonics - Definitions and Measurements
Thanks Mark, Ashar and Curt.
Mark I did look but I didn't figure it would be in Part 97.? What I did find was a procedure written by the IEEE which gave step by step how to test for the spurious emissions.? But, if you look closely at what is written in what you highlighted, the emitted spurious power for a low power rig can be interpreted to be far lower than for a higher power transmitter.? In the second part, those dealing with transmitter installed before 2005, achieving this goal with a high power transmitter might be excrutiatingly difficult but may be easy to achieve with a low power transmitter.? In the first part, they are specifying according to suppression.? In the second part, they list the actual emitted power permitted.? Things are not equal.? It would be better is everyone measured using the same units.
And, yes, it can be such gibber when even the regulations don't seem to agree within the same paragraph.? I do realize they are addressing two different vintages but they are using two different measuring systems.
My additional nickel.
Bruce, K4TQL
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Re: AGC Pre-Oders are in and built!
Thought I would post a live stream building the next batch enjoy
http://47.224.85.241:48461/
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David
?N8DAH
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Re: Spurs and Harmonics - Definitions and Measurements
Bruce
Mark adds some clarity.? Those measurements you describe relate to 'unintended' radiation apart from the antenna connector path - yes we often experience this in our homes and workplaces.? In the uBITX we are mostly interested in what comes from the antenna connector - sometimes called conducted spurious.? As we are world-wide, we might find that other nation's requirements may be similar to those here in the US - some may be more stringent perhaps.?
As Farhan points out, the regulation is in dBc (relative power) versus the real-world phenomena relating to receiving absolute signal strength in dBm.? But the regulations may not allow our argument.? [I also asked my local fellow club members about those speed limit signs, and how often we might exceed those by just a little ... but they weren't interested in my analogy!].?
Regulations tend to be even tougher in VHF and UHF, due in part to criticality of emissions in that spectrum.?
Practically, it is good practice to work our uBITX transceivers into our own nation's requirements.? We are collectively challenged as few of us possess spectrum analyzers.? A recipe for modifications that provides a little performance margin would be nice.? We don't yet that I know of have technical consensus on the solution.? I suggest we not major on one particular board being the measure of solution as there is some variation in levels across the population.? I like adding relays for the harmonic issue as I think it should provide conservative margin - I am not sure of the best solution for 45 MHz related IF spurious.?
Curt
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Ordered my v5 ubitx today, case delivery tomorrow!
Boy am I excited!? My case from amateurradiokits.in is almost here, and I was able to order my V5 ubitx today!?
Kelly K5AID?
Sent from my Verizon, Samsung Galaxy smartphone
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A circuit board contains 3 added relays that connect to the input side of the 4 low pass filters.? Following assembly of this board, the user must cut a few traces and then install short pieces of thin coax to make the connection.? A pc board was designed by a list member, only the artwork is available.? Our club made a batch of these boards and kitted the needed parts - a few of us have them installed into our uBITX, but I only know of one unit being measured so far - it passed with margin.? My v4 needs over 10 dB improvement in the harmonics on some bands - I don't know if change to the alternate relay will achieve this or not.?
Now if this solution would be preferred - then 'all' that is needed is for someone(s) to kit and sell it maybe.? Clarifying, this fix only address one source of spurious.? Curt
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Re: ubitx v4 - distortion in received audio
On Mon, Mar 11, 2019, at 6:57 PM, Mark - N7EKU wrote:
Hi Ramakrishnan,
Not sure if your audio problem is related to the audio amp section, but if it is this link shows a fix that shouldn't be too hard to do:
Make sure you read Allison's post number 53356 in that link for adjusting the operating point of Q71.
Thanks so much Mark. I also spoke to Raj. I will try the modification tomorrow and report back.
73
Ramakrishnan VU3RDD
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That's excellent! I didn't do anything further. I removed my hmi upload so it could be tested before too many people downloaded it.
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Re: Spurs and Harmonics - Definitions and Measurements
Bruce, Your point is well noted. I made a similar argument. It ia true that a -40 dbc at 10 watts is less than -48 dbc at 100 watts.? However, this is largely a challenge of compliance. The FCC mandates that all spurious emissions should be at least -43 dbc. So, that's what we shoot for. This figure is meant only for radios manufactured after 2005. Your vintage gear need not be fixed. - f
On Mon 11 Mar, 2019, 7:14 PM BruceN, < k4tql@...> wrote: I've seen many messages relating to the cures for spurs and harmonics for the V3, V4 and V5 units.? Right now there are nearly 1000 messages dealing with this topic.? But, I'm confused.? And, what exactly are the limits for emission of spurs and harmonics?? I've researched the FCC regs and it's like reading a foreign language to me.? But what I did glean is that the FCC tests in, basically, an anechoic (to RF) chamber and report the results, depending on frequency range, in microvolts.
What I see in the messages is that folks are reporting spur and harmonic levels in dB.? Now, db is a ratio so what are those db values compared to?? To the level of the primary signal?? Are they measuring spur and harmonic suppression?? Again, compared to what??
If spurs and harmonics readings are to be given as a particular level, they should be reported as dBm, not dB.? dBm is also a ratio but it is compared to a fixed level of 1 milliwatt.? The emitted power given in those units would be the same if measured on a transmitter running 10 watts as a transmitter running 100 watts.
However, if the readings are given in dB, it is representing suppression.? A -50 dB reading on a 10 watt transmitter will have an actual radiated power far less than a -50 dB reading on a 100 watt transmitter.? So, if we're measuring and reporting dB on the uBitx, maybe those reported levels are not so bad as folks think.? The radiated power level would be far less than other signals out there.? Easily seen on a scope with high gain but maybe not readable a mile away or even 3 feet away.
If you are measuring actual output power of the spurs and harmonics, report your readings in dBm.? And if that is the units being used, the uBitx might need some help.
So which is it?
My nickel (2 cents inflated).
Bruce, K4TQL
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Re: Spurs and Harmonics - Definitions and Measurements
Is is really such gibber? You seem to have a good understanding of dB.? Here's the text on the specific levels: ¡ì97.307???Emission standards.
...
(d) For transmitters installed after January 1, 2003, the mean power of any spurious emission from a station transmitter or external RF power amplifier transmitting on a frequency below 30 MHz must be at least 43 dB below the mean power of the fundamental emission. For transmitters installed on or before January 1, 2003, the mean power of any spurious emission from a station transmitter or external RF power amplifier transmitting on a frequency below 30 MHz must not exceed 50 mW and must be at least 40 dB below the mean power of the fundamental emission. For a transmitter of mean power less than 5 W installed on or before January 1, 2003, the attenuation must be at least 30 dB. A transmitter built before April 15, 1977, or first marketed before January 1, 1978, is exempt from this requirement.
Seems pretty clear at least for US FCC regulations.? I'm not sure about other countries.
I think most reporting Spectrum Analyzer results here are talking about dB down from the fundamental.
73,
Mark.
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Spurs and Harmonics - Definitions and Measurements
I've seen many messages relating to the cures for spurs and harmonics for the V3, V4 and V5 units.? Right now there are nearly 1000 messages dealing with this topic.? But, I'm confused.? And, what exactly are the limits for emission of spurs and harmonics?? I've researched the FCC regs and it's like reading a foreign language to me.? But what I did glean is that the FCC tests in, basically, an anechoic (to RF) chamber and report the results, depending on frequency range, in microvolts.
What I see in the messages is that folks are reporting spur and harmonic levels in dB.? Now, db is a ratio so what are those db values compared to?? To the level of the primary signal?? Are they measuring spur and harmonic suppression?? Again, compared to what??
If spurs and harmonics readings are to be given as a particular level, they should be reported as dBm, not dB.? dBm is also a ratio but it is compared to a fixed level of 1 milliwatt.? The emitted power given in those units would be the same if measured on a transmitter running 10 watts as a transmitter running 100 watts.
However, if the readings are given in dB, it is representing suppression.? A -50 dB reading on a 10 watt transmitter will have an actual radiated power far less than a -50 dB reading on a 100 watt transmitter.? So, if we're measuring and reporting dB on the uBitx, maybe those reported levels are not so bad as folks think.? The radiated power level would be far less than other signals out there.? Easily seen on a scope with high gain but maybe not readable a mile away or even 3 feet away.
If you are measuring actual output power of the spurs and harmonics, report your readings in dBm.? And if that is the units being used, the uBitx might need some help.
So which is it?
My nickel (2 cents inflated).
Bruce, K4TQL
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I have had 2 of the original volume controls with similar problems. The contact pin rivets had intermittent connections to the resistance substrate. They were going open. I changed to 10K audio taper controls that I had and the problem never reoccurred. Noises and unexplained distortions disappeared.
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Hi Curt,
Can you elaborate on the "three relays on a daughter card" fix? I don't need a kit - I'll make my own!
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Jim
N8DAH
Ramakrishnan Muthukrishnan
Don, ND6T