Bruce, K4TQL

Small point...the FCC monitors would be testing received RF. This may be via a remote monitoring
station or from a van parked down the street from your house. This means that the full system,
including ATU and antenna will be present in signal analysis. Most discussions fail to include
filtering effects of these components that are external to your transceiver (some designs are better
than others). This lends credibility to having another ham who is some distance from your location
perform tests to see how pure your signal might be.

Testing in an anechoic chamber is the way equipment is tested for type approval or in case of
legal proceedings.

Arv K7HKL
_._



On Mon, Mar 11, 2019 at 7:44 AM 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

Bruce, K4TQL

?

Small point...the FCC monitors would be testing received RF.? This may be via a remote monitoring

station or from a van parked down the street from your house.? This means that the full system,

including ATU and antenna will be present in signal analysis.? Most discussions fail to include

filtering effects of these components that are external to your transceiver (some designs are better

than others).? This lends credibility to having another ham who is some distance from your location

perform tests to see how pure your signal might be. ?

?

Testing in an anechoic chamber is the way equipment is tested for type approval or in case of

legal proceedings.?

?

Arv? K7HKL

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

I see no reason why we should not be compliant. It is just that we are trying to be cost effective in doing so.

- f

On Tue 12 Mar, 2019, 12:22 AM Jerry Gaffke via Groups.Io, <jgaffke=[email protected]> wrote:

The regs changed, and old gear is grandfathered in.
The uBitx is new gear, should meet the -43dBc spec here in the USA.
Simple as that.

> What I did find was a procedure written by the IEEE which gave step by step how to test for the spurious emissions.??

Part 97 applies specifically to Amateur Radio, and specs -43dBc.? Search for "97.307" within this document:
? ??

Part 15 deals with RFI from non-licensed devices, and is a whole other kettle of fish.
? ??
Since such devices do not necessarily radiate on purpose, there may be no carrier to compare the emission with.
So the regs are written much differently.

Generally speaking, regs for Amateur Radio seem fairly lax.
Especially that grandfather thing.

And generally speaking, these particular regs seem pretty simple and self consistent.
Government regs can get a whole whole lot worse.? ?;-)

Jerry, KE7ER


On Mon, Mar 11, 2019 at 09:51 AM, BruceN wrote:

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

Everyone has a right to their opinions, but you can’t order manufacturers around. If there are customers who value their products, manufacturers will sell them.

If you want strongly to have more filtering, this is a perfect opportunity for you to start doing what you feel the manufacturer has left incomplete. This is ham radio! This is not CB. This is not family radio service.

You can build it yourself, or you can go into business and manufacture it for others and try to make a profit! (Good luck.)

Here is a webpage that gives some design information for band pass filters


I’m sure there are many others.

If you just want more low pass filtering, add in external relays and toss in one extra section on the low pass filter. The Gerber files for the external relay system that I built are free. Send them to china with $25 and you’ll have five or 10 boards to experiment with!


When I was a novice 40 years ago, heathkit sent me a COMPLETELY unassembled radio! You had to Solder & place every single part of it together and then you worked and worked to fix your goofs and make the thing work. They bitx products are already assembled and we have tons of documentation of their characteristics. You are free to improve on them! Again, this is him radio. This is not CB. This is not family radio service.

Pick up a soldering iron and get to work!


Cheers

Gordon


On Mar 11, 2019, at 15:46, Ashhar Farhan <farhanbox@...> wrote:

I see no reason why we should not be compliant. It is just that we are trying to be cost effective in doing so.

- f

On Tue 12 Mar, 2019, 12:22 AM Jerry Gaffke via Groups.Io, <jgaffke@...> wrote:

The regs changed, and old gear is grandfathered in.
The uBitx is new gear, should meet the -43dBc spec here in the USA.
Simple as that.

What I did find was a procedure written by the IEEE which gave step by step how to test for the spurious emissions.

Part 97 applies specifically to Amateur Radio, and specs -43dBc. Search for "97.307" within this document:


Part 15 deals with RFI from non-licensed devices, and is a whole other kettle of fish.

Since such devices do not necessarily radiate on purpose, there may be no carrier to compare the emission with.
So the regs are written much differently.

Generally speaking, regs for Amateur Radio seem fairly lax.
Especially that grandfather thing.

And generally speaking, these particular regs seem pretty simple and self consistent.
Government regs can get a whole whole lot worse. ;-)

Jerry, KE7ER


On Mon, Mar 11, 2019 at 09:51 AM, BruceN wrote:

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