Decade MS-100 on 87.9

Very little known secret.

There are numerous flip switches that set the frequency, if you look very closely, one possible configuration that is not listed in the owners manual, that setting is 87.9MHz, however there is no possible configuration for 87.7 or 87.5 though. Edited to add and no possible combination to go above 107.9MHZ. So going into the aircraft band is not possible at all either.

It was found using a frequency counter and a switch combination that is NOT listed in the instruction manual.

Bruce.

Oh and the highest frequency is 107.5MHz, I never seen 107.7 or 107.9 show up on the frequency counter, so those are out of the question.

Bruce.

The Decade can't run on 87.9.....The frequency range is 88.1 to 107.5, the legal allowable for Canada. The CM-10 which is a modified CZH Chinese transmitter has also been modified to not transmit lower than 88.1  All the other transmitters from China can transmit from 74 to 108 because there the FM band starts at 74 MHZ and in Russia it's 64 to 108MHZ. North America is where it's 88 to 108. All the other Certified transmitters I believe also don't go lower than 88.1

It would be good to go on 87.9 or 87.7 with no other stations there and most radios tune to those.

Or maybe MrBruce knows a secret there....haven't tried but maybe Artisan knows about this.

Mark

We didn't know about that setting for 87.9MHz either until we hooked up a frequency counter and tried some interesting combinations. The owners manual clearly says 88.1 to 107.5 as I stated above in my last two posts, but if you look at the possible combinations of those BITS flip switches very closely, something reveals a secret. It does not have 107.7 so the next possibility is at the lower end of the band which is 87.9MHz.

The manual http://www.proaudiosuperstore.com/pdf/MS100-Manual.pdf

I know you want me to reveal the secret combination, but if it was published in the manual I would feel okay to do so here. The only hint I'll give is try every combination with a frequency counter and you've found it, that's the easiest way to do it.

Edited to add: And NO it can NOT go down to 87.7MHz or lower.

Bruce.

I kinda fugured that was the case. 🙂

Thre are so many combinations possible that it would be a needle in a haystack trying to find the right one.....especially if you can't transmit there anyway.

Mark

Mark said:

especially if you can't transmit there anyway.

At Mark

According to the FCC I suppose you're right, but then again, for a device that has such short range why would it matter? In areas where LPFM and Full powered licensed stations have consumed the entire FM band, 87.7MHz and 87.9MHz are your only viable options for frequencies that you can use for wireless devices such as an MP3 player to FM radio.

Again, I'll stress my point I made in another thread, the FCC and the NAB need to be shut down permanently, not the 'pirates' they waste our government tax dollars on, those pirates serve their communities way better then any NAB member and for free.

Bruce.

The C.Crane only goes to 107.5 not 107.9 and the lowest frequency it will transmit is 88.1.  The SainSonic AX-05B which is certified and has an FCC ID out of the box goes to 88.1 for the low and 107.9 for high and the power level is -48Dbm at the out of box low power mode.

Thelegacy said:

The C.Crane only goes to 107.5 not 107.9

Did a post get removed? I looked back in this thread and did not see anyone state differently, perhaps I am misunderstanding your point of using the word NOT. That would mean someone claimed differently.

 My mention of 107.9Mhz was purely to state that the MS100 can not tune above the FM band at all if that was what was being referenced in this topic.

The Decade MS100 can do 87.9MHz to 107.5 MHZ though, but 87.9 MHz is NOT mentioned for some reason.

Reminds me of the old 23 channel CB radios that had that hidden channel 22A, some CBs tuned to it and some would not. Depended on the size of the notch in the selector switch between channel 22 and channel 23.

Bruce.

I remember those days. I also remember channels 3a 7a 11a 15a and 19 a and if you were really good you could slowly slide the selector and get there.  I remember those channel jumping days.  We will see uf 87.9 becomes legal but something tells me it will be it will just take time.  it actually would be in the NAB's best interest.

What is interesting is while 87.9 is not permitted for Part 15 it is FM Channel 200 and there is a FM station licensed on that frequency. My guess is that TV Channel 6 being common at the time would be vulnerable to Part 15 devices if used in a neighborhood as the sound portion of TV is/was frequency modulated. That being said, Part 15, Subpart J limits were designed to primarilly protect licensed broadcast services both AM & FM to include television.

The Decade has 8 tuning switches, so there are 2*2*2*2*2*2*2*2=256 possible settings for the switches. The table in the manual has 98 switch settings in it. So that leaves 158 switch settings that could do something. It could be some of the unpublished settings do even channels (88.2, 88.4, etc). Or there may be some sort of logic that sits between the DIPP switches and the PLL that prevents invalid settings from selecting an illegal channel. If someone with a frequency counter/scope wanted to, they could count through all 256 binary settings and see what channel each one did. Other than many car radios not being able to tune to even channels, there is nothing illegal about transmitting on them. On the other hand, if it can actually do 76.9 to 127.9, using channels outside of 88-108 would be breaking the rules.

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I don’t see 87.9 being opened up for FM. Cell phone companies with deep pockets want the UHF TV channels. TV stations that rely on must carry to reach most of their target audience will be fine with DTV on VHF TV channel 6. Channel 6 is underused at the moment nationally, but it will not be after the incentive auction and repack.

Even if the FCC allows licensed FM stations to use 87.9 (most likely translators, possibly LPFM’s), it will be after the TV repack; LPTV’s will get first dibs at 82-88MHz. Then any FM users who want 87.9 will need to convince the FCC to let them shoehorn in their signals between full power DTV and low power TV on channel 6 stations, as well as anyone who is using first adjacent 88.1MHz.

In case anyone has missed it, FM is going the way AM did

Potential licensees convinced the FCC to tolerate more noise and short spaced stations were shoved into the AM band. The result was adjacent channel noise that led to radio manufacturers restricting the frequency response of AM tuners.

On FM there is a triple punch.
1. IBOC causes noise on adjacent channels.
2. The trend of modifying translators to have as much HAAT and ERP as can be fit between full power stations is ongoing. Do a nationwide search for translators with applications or CP’s, the number of filings is scary.
3. LPFM’s are great for getting local radio on the air, but firms specialized in shoehorning them onto the dial in crowded markets.

The FCC is interested in making money from the airwaves. AM stations desperately want an AM exclusive opportunity to file for FM translators. That was on the table; until someone looked at it and realized FM stations that want to get HD2/3/4’s onto FM translators were probably willing to pay more for translators so if there is another translator window, it will be a free for all. Mutually exclusive applications will go to auction.

All together that leaves 3 types of licensed use for 87.9
1. DTV channel 6
a. Full power
b. Low power, possibly with analog audio on 87.7
2. IBOC from 88.1
3. Analog FM on 87.9
a. Primary users (full power stations)
b. Secondary users (translators)
With all of that, part 15 operation on 87.9, if they were legal, would be heavily limited by not interfering with the licensed user of the spectrum.