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Differences between US and UK Amateur Radio license rules and restrictions – part 2

A while back I posted this article about some of the differences I’ve noticed while studying for a UK Amateur Radio license compared to the US license rules. I’ve just come across a few more about geographic restrictions, which are probably amongst the most curious of the license rules.

US Geographic Restrictions

In the US, the Part 97 rules define a couple of geographic areas where you’re not allowed to transmit.

97.303 states:

(m) In the 70 cm band:

(1) No amateur station shall transmit from north of Line A in the 420-430 MHz segment. See §97.3(a) for the definition of Line A.

And defines Line A as:

(30) Line A. Begins at Aberdeen, WA, running by great circle arc to the intersection of 48° N, 120° W, thence along parallel 48° N, to the intersection of 95° W, thence by great circle arc through the southernmost point of Duluth, MN, thence by great circle arc to 45° N, 85° W, thence southward along meridian 85° W, to its intersection with parallel 41° N, thence along parallel 41° N, to its intersection with meridian 82° W, thence by great circle arc through the southernmost point of Bangor, ME, thence by great circle arc through the southernmost point of Searsport, ME, at which point it terminates.

The reason for this restriction is that Canada does not allow 70cm Amateur Radio usage between 420-430Mhz and so this corridor along the North US border with Canada and between Alaska and Canada is to prevent interference with other primary users of 420-430MHz.

There are a couple of other location specific restrictions stated in Part 97 for US operators:

(2) Amateur stations transmitting in the 420-430 MHz segment must not cause harmful interference to, and must accept interference from, stations authorized by the FCC in the land mobile service within 80.5 km of Buffalo, Cleveland, and Detroit. See §2.106, footnote US230 for specific frequencies and coordinates.

Since 70cm band usage is on a secondary user basis, restrictions are to prevent interference with primary users in these areas.

The US Part 97 rules also mention restrictions for the National Radio Quiet Zone in Virginia – this location contains the Green Bank Observatory and a Naval Research Station. Part 97.203 mentions restrictions to automated beacon stations in this area.

Another interesting restriction on 70cms is the power restriction to 50w in locations near to particular military bases. Having lived in the Sacramento Valley area, this 70cms restriction is known to the local clubs and operators as a measure to avoid interference within 150 miles of the PAVE PAWS radar at Beale AFB.

UK Geographic Restrictions

I’ve only come across these similar UK restriction so far, stated on the license bandplan:

431 to 432 MHz is not available within 100 km radius of Charing Cross, London

As UK 70cm usage is as a secondary user, this is again to avoid interference to primary users in this band.

On 2m:

Beacons may be established for DF competitions except within 50 km of TA 012869 (Scarborough)

If anyone knows what is specifically at this location leave a comment below, although this RSGB page and map may give some clues since Menwith Hill is also mentioned here as another area with restrictions.

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Amateur Radio – remembering Ohm’s Law with the VIR triangle (and the PIV triangle)

For the Amateur Radio license exams (for most countries) you need to remember Ohm’s Law, which is easily remembered by the Ohm’s Law triangle:

 V
I R

where:

V = voltage (volts)

I = current (amps)

R = resistance (ohms)

To calculate any value knowing the other 2, cover the value you need with your finger and then use the remaining calculation, e.g.

V = I x R

I = V / R

Similarly for Power, use the PIV triangle:

 P
I V

where:

P = power (watts)

I = current (amps)

V = voltage (volts)

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New developers: “How do I know what to learn and when I’ve learned ‘enough’ ?”

A question frequently asked by new developers is what to learn, how much to learn, and how do you know when you’ve learned enough?

Learn what you need to solve the current problem and then repeat for the next problem.

Don’t think about his as a finite set of knowledge that you need to learn and then that’s it, that’s the end. That’s not how it works. There’s always something new to learn, and there’s always something you’ll find that you don’t know.

Adjust your mindset to keep this in mind and you’ll be ok.

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My last 4 phones over the past 13 years (all still work)

For some reason I though I’d sold some of my last phones on ebay, but after clearing out some shelves and cupboards in our house, I’ve found my last 3 phones before my current phone, and they all still work fine. It’s interesting how large current phones are now compared to phones from over 10 years ago – we definitely had a period of phones getting smaller, and now we’re carrying around tablets in our pockets.

Here’s the oldest to last phone I replaced:

From left to right:

  • T-Mobile myTouch4g – this is from roughly 2010. I had it for a few years then reached that stage when it started to slow down so installed a custom Android ROM, Lineage. This always seems to be my sign where I need to upgrade, when I start messing with custom ROMs. Pretty sure I used this phone for at least 3 years. Given it’s small size, it’s noticeably heavy in the hand, maybe because of the solid metal back plate.
  • Samsung S3 – used this phone for 5 years, and only upgraded because the battery started to only just last for a whole day before needing a recharge. Still, 5 years for continual daily use is pretty good innings. I would have used it for longer if it wasn’t for the battery life decreasing
  • Samsung S8+ – probably my favorite phone so far. Even though I recently upgraded to an S21 ultra, I used this phone at home as a music player while working from home (before most recently getting replaced by an iPad)

As a comparison in size to my current S21 Ultra, here’s the myTouch and S3 to the left, S21 Ultra on the right:

It’s interesting seeing the increase in size. My S21 feels completely normal at this point, but the myTouch4g is small enough to fit within my hand.

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