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[AE5X]

Some here may be interested in this upcoming product from TA2MUN:

https://ae5x.blogspot.com/2019/03/lightaprs-tracker-de-ta2mun.html

[TA2MUN]

Thanks for sharing 

LightAPRS is available on : http://shop.qrp-labs.com/lightaprs

Source code : https://github.com/lightaprs/LightAPRS-1.0

[N4SRN]

That looks pretty nice! I have a picoAPRS V3 but if I planned to shoot a balloon up this would be a consideration.

BRET/N4SRN

[KF6IIU]

That looks like an interesting project, particularly with the included RF module. I wonder if anyone has checked the Dorji module for spectral purity? It's main chip is a Baofeng RDA1846. Some of those Baofeng radios emit as much power on frequencies outside the ham bands as they do on the frequency you have them set to!

[WD9EWK]

That looks like an interesting project, particularly with the included RF module. I wonder if anyone has checked the Dorji module for spectral purity? It's main chip is a Baofeng RDA1846. Some of those Baofeng radios emit as much power on frequencies outside the ham bands as they do on the frequency you have them set to!

The RDA1846 (and its triband version RDA1846S, including spectrum at and above the amateur 222 MHz band) are not made by Baofeng. The manufacturer of the chip was RDA Microelectronics, and I think it was acquired by another company. In any event, the chip can be used in transceivers without the spurious emissions as you see with the Baofeng radios and radios from other Chinese brands - if there is filtering in place.

Yaesu's FT-4XR 2m/70cm FM HT is based on the RDA1846S like many of the Chinese brands. Razvan YO9IRF/M0HZH opened up one of those radios last year, and showed the insides:

https://qrpblog.com/2018/09/yaesu-ft-4x-review-it-is-after-all-a-baofeng/

The May 2019 QST has a product review of the FT-4XR. ARRL's testing shows that the FT-4XR complies with FCC regulations on spectral purity, not transmitting all of the junk like some of the Baofeng HTs. If you are an ARRL member with an account on the ARRL web site, you can see this review at:

http://www.arrl.org/files/file/protected/Group/Members/ProductReview/PROD_REV_0519.pdf

By itself, the RDA1846 or RDA1846S may not meet FCC regulations, unless transmitting at extremely low power levels. With the proper filtering in place, it appears that these chips can be the basis of radios that meet the appropriate requirements.

73!

[KF6IIU]

Thanks. Interesting review. The first few datasheets I found online were "Baofeng propietary".

We're in N CA and subject to extreme 70cm band emission limits because of the Pave Paws radar at Beale AFB.  A bare RDA module might be complaint at 1W but I'd hate to be the guy spamming the USAF with a 144mhz 3rd harmonic.

I looked at https://hackaday.com/2016/12/14/measuring-spurious-emissions-of-cheap-handheld-transceivers/ I'd guess even Baofeng puts at least a little filtering on those modules, or they would be useless within a mile of a big commercial antenna site. I operate a fair amount near those sites and my Icoms and Yeasus are pretty good. I'll have to take a Baofeng up there and see what happens.

That review says: "The intended market for these radios is more the unlicensed crowd than the compliant ham" :-(. And yeah I have had more than a few "hackers" show me their 2m radios (and I convinced at ;east one to get his tech license. Hooray.)  One coworker had a 50W radio in this truck, tuned to FM simplex on 144.000, and he and his buddies used this mode to 10-4 good buddy each other up the mountains.

[TA2MUN]

Our new module LightAPRS WSPR just released : http://qrp-labs.com/lightaprs-w

Github: https://github.com/lightaprs/LightAPRS-W-1.0