Looking for volunteer to design a tiny CW transceiver for socially isolated kids/teens

[Jeff Kabel]

1) Wouldn't it be better to use one of the ISM bands? Then licensing is not
a problem. I'd feel uncomfortable giving radios that operate in the ham
bands to people without a license. There are bands 6.765-6.795MHz,
13.553-13.567MHz, and 26.957-27.283 close to our 40, 20, and 12/10 meter
bands, and a number of bands in the VHF+ range. The 13MHz one is used by
the HiFER <https://en.wikipedia.org/wiki/LowFER> experimenters already.
There are also the LowFER and MedFER bands.

2) Does the pixie not meet the requirements? They're cheap ($3-5 on eBay),
low power (~150mW), and have QSK. The kits you buy don't have a volume
control, but that is simple to add.


-- Jeff aa6xa
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[ktalbott]

I've spent hours playing with Pixies. Good choice only if keying is cleaned
up.
Ken ke4rg

-----Original Message-----
From: [hidden email] <[hidden email]> On
Behalf Of Jeff Kabel
Sent: Thursday, October 17, 2019 7:08 PM
To: [hidden email]
Subject: [Elecraft] Looking for volunteer to design a tiny CW transceiver
for socially isolated kids/teens

1) Wouldn't it be better to use one of the ISM bands? Then licensing is not
a problem. I'd feel uncomfortable giving radios that operate in the ham
bands to people without a license. There are bands 6.765-6.795MHz,
13.553-13.567MHz, and 26.957-27.283 close to our 40, 20, and 12/10 meter
bands, and a number of bands in the VHF+ range. The 13MHz one is used by the
HiFER <https://en.wikipedia.org/wiki/LowFER> experimenters already.
There are also the LowFER and MedFER bands.

2) Does the pixie not meet the requirements? They're cheap ($3-5 on eBay),
low power (~150mW), and have QSK. The kits you buy don't have a volume
control, but that is simple to add.


-- Jeff aa6xa
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[k6dgw]

If they're unlicensed, they will be intentional radiators subject to
47CFR15 Subpart C [15.201 et seq] which imposes field strength limits
that vary with frequency. 15.201(b) may also require certification. 
Depending on choice of frequency, 150 mW may be way too high since in
the 1.7 - 30 MHz range, the limit is 30 uV/m at 30 m.  I think Wayne has
hit on a great idea, it's just going to take some Part 15 engineering.

73,
Fred ["Skip"] K6DGW
Sparks NV DM09dn
Washoe County

On 10/17/2019 4:07 PM, Jeff Kabel wrote:

> 1) Wouldn't it be better to use one of the ISM bands? Then licensing is not
> a problem. I'd feel uncomfortable giving radios that operate in the ham
> bands to people without a license. There are bands 6.765-6.795MHz,
> 13.553-13.567MHz, and 26.957-27.283 close to our 40, 20, and 12/10 meter
> bands, and a number of bands in the VHF+ range. The 13MHz one is used by
> the HiFER <https://en.wikipedia.org/wiki/LowFER> experimenters already.
> There are also the LowFER and MedFER bands.
>
> 2) Does the pixie not meet the requirements? They're cheap ($3-5 on eBay),
> low power (~150mW), and have QSK. The kits you buy don't have a volume
> control, but that is simple to add.
>
>
> -- Jeff aa6xa
>

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[Elecraft mailing list]

Wayne was looking for 1mW output.  How does that equate in regard to the regs?

David G3UNA

> On 18 October 2019 at 22:58 Fred Jensen <[hidden email]> wrote:
>
>
> If they're unlicensed, they will be intentional radiators subject to
> 47CFR15 Subpart C [15.201 et seq] which imposes field strength limits
> that vary with frequency. 15.201(b) may also require certification. 
> Depending on choice of frequency, 150 mW may be way too high since in
> the 1.7 - 30 MHz range, the limit is 30 uV/m at 30 m.  I think Wayne has
> hit on a great idea, it's just going to take some Part 15 engineering.
>
> 73,
> Fred ["Skip"] K6DGW
> Sparks NV DM09dn
> Washoe County
>
> On 10/17/2019 4:07 PM, Jeff Kabel wrote:
> > 1) Wouldn't it be better to use one of the ISM bands? Then licensing is not
> > a problem. I'd feel uncomfortable giving radios that operate in the ham
> > bands to people without a license. There are bands 6.765-6.795MHz,
> > 13.553-13.567MHz, and 26.957-27.283 close to our 40, 20, and 12/10 meter
> > bands, and a number of bands in the VHF+ range. The 13MHz one is used by
> > the HiFER <https://en.wikipedia.org/wiki/LowFER> experimenters already.
> > There are also the LowFER and MedFER bands.
> >
> > 2) Does the pixie not meet the requirements? They're cheap ($3-5 on eBay),
> > low power (~150mW), and have QSK. The kits you buy don't have a volume
> > control, but that is simple to add.
> >
> >
> > -- Jeff aa6xa
> >

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[k6dgw]

It depends on a number of factors.  Here in the Colonies, our beloved
version of OFCOM has defined three types of unlicensed radiators: 
Incidental, Unintentional, and Intentional.  Incidental are those that
make RF as part of their operation but don't need to and it serves no
purpose in their operation.  Basically noisemakers like PWM motor
controls or arcing HV lines.  Unintentional are those that create RF as
part of their operation but do not intend or need to radiate it.
Computers are probably the best example, a one-tube regenerative RX is
another.  Intentional are those that make and radiate RF as an integral
part of their operation.  Remote sensing thermometers and weather
stations are a good example ... so is Wayne's 1 mw TX.  They are all
regulated by Part 15 of the FCC's regulations. 2.4 and 5.6 GHz Wi-Fi and
Bluetooth devices are all covered by Part 15.  There are also duty cycle
limits in some regions of the spectrum.

A big factor is the antenna, and one requirement of Part 15 is that the
user be unable to modify it.  That's why I used the term "Part 15
Engineering," one will have to test and certify that the device meets
the Part 15 requirements including the field strength.  150 mW on 6 MHz
with a 0 dBi antenna will produce a field strength of about 0.07 V/m at
30 m which is way over the limit.  1 mW will be about 0.006 V/m or so. 
A very limited antenna with something like -15 to -20 dBi "gain" would
probably bring the field strength down sufficiently, provided the user
can't get to it to modify it.

I'd consider randomizing the TX frequencies within a very small [~5-10
kHz?] "band" [like padding the xtals] and making the RX tuneable over
that band so a group could have individual "conversations" such as at a
Scout meeting or in a classroom.

73,
Fred ["Skip"] K6DGW
Sparks NV DM09dn
Washoe County

On 10/19/2019 12:29 AM, CUTTER DAVID wrote:

> Wayne was looking for 1mW output.  How does that equate in regard to the regs?
>
> David G3UNA
>
>> On 18 October 2019 at 22:58 Fred Jensen <[hidden email]> wrote:
>>
>>
>> If they're unlicensed, they will be intentional radiators subject to
>> 47CFR15 Subpart C [15.201 et seq] which imposes field strength limits
>> that vary with frequency. 15.201(b) may also require certification.
>> Depending on choice of frequency, 150 mW may be way too high since in
>> the 1.7 - 30 MHz range, the limit is 30 uV/m at 30 m.  I think Wayne has
>> hit on a great idea, it's just going to take some Part 15 engineering.
>>
>> 73,
>> Fred ["Skip"] K6DGW
>> Sparks NV DM09dn
>> Washoe County
>>
>>

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