Many thanks to SWLing Post contributor, Dan Van Hoy, who writes:
Because I [purchased a RT-470L last year], Radtel sent me news of their brand new RT-860. No need to mod the radio like a Quangsheng. It does LW/MW/SW with SSB/CW (rx only, of course) out of the box for less than $50! I just posted a short preliminary review of the RT-860 on YouTube:
An AM signal consists of a carrier, a lower and an upper sideband. The sidebands spread out identically either side of the carrier. The carrier frequency is what is shown on the radio dial.
In the Americas, carriers are multiples of 10 kHz apart hence frequencies like 720, 730,….
In the rest of the world the carriers are multiples of 9 kHz apart like 720, 719,…
Stations who transmit audio of 10 kHz on a carrier of 720 kHz will have an output of 710, 720 and 730 kHz
in an adjacent channel at 719 kHz transmitting the same 10 kHz will have an output of 709, 719 and 729 kHz
If the radio is tuned to 720 kHz it will receive 720 – 709 = 11 kHz, also 720 – 719 = 1 kHz and again 720 – 729 = -9 kHz. Negative frequencies do not exist so it is heard as 9 kHz. To stop this interference AM radio manufactures limit the received audio frequency range to under 4.5 kHz for worldwide use.
In North America HD radio in the MF band ±15 kHz for an analog/digital simulcast and pure digital is either ±15 kHz or ± 5 kHz. The carrier is retained in all of these modes. All other digital broadcast modes do not waste power on a carrier.
So, since ‘HiFi’ AM requires either 2 or 3 AM channels may have been ok when there were not many AM broadcasters the adjacent channels were unused, making AM receivers having a wide frequency mode is feasible. Now there are so many AM broadcasters and HD radio makes a horrible noise, the use of a wideband mode is not feasible. Receiver manufacturers don’t want complaints so restrict the audio bandwidth to telephone quality with bass!
You can buy the RT-860 on Amazon.
So, is there wide and narrow bandwidth option in AM? That would make sense but haven’t seen it in reviews.
Thanks Dan for this presentation; always up to date with the latest technological advances!
Rather than a comment, I’d like to add some information I found on the web:
1 – Next Generation HT’s – Quansheng TK-11 – Radtel RT-860
https://www.youtube.com/watch?v=NTWMlFnDbKU
2 – And of course Quansheng’s announcement of two radios, TK-11 and TK-11(8) :
https://hamimports.com/quansheng-tease-specs-and-features-of-their-next-handheld-taiko-kong-tk-11/?
Note that Quansheng offers a specific antenna for the LW/MW/SW range, reminiscent of the TECSUN PL-36X …
It will be very interesting to compare the performance of these two radios … especially when listening to HF bands …
Wow! Talk about weird! I had not heard of this radio until last night when a friend checked into an amateur radio Net I run with it and then contacted me after the net to ask how the signal was. He told me about the radio and I bought one from Ali Express because the price was so reasonable (not like I really need another handheld!). The receive range is quite amazing for the price, looking forward to getting it!
Cheers!