RT97S wideband operation

[colbypr]

I was looking at the Retevis RT97S and noticed the specifications listed both narrow (11K03FE) and wide (16K03FE) capabilities. The FCC grant for the device only shows the narrowband 2.5khz designator, 11K03FE.  Has anyone else noticed this? I couldn't find any other grants for their company for the portable repeater that listed the wideband 5khz emissions designator (16K03FE), even though the programming software and literature for the radio clearly let you set Wideband or Narrowband.

In fact, I checked a bunch of their other GMRS transceivers and none of them appear to have the wideband emissions designator grant, only narrow.

 

[gortex2]

Nope. Many GMRS/FRS units are narrowband. There are radios that will do wideband. If you plan on many repeaters then I'd shop around. If your plan is to talk to your buddy in the vehicle behind you or to a neighbor narrowband works just fine. 

[aa7jc]

2 hours ago, colbypr said:

I was looking at the Retevis RT97S and noticed the specifications listed both narrow (11K03FE) and wide (16K03FE) capabilities. The FCC grant for the device only shows the narrowband 2.5khz designator, 11K03FE.  Has anyone else noticed this? I couldn't find any other grants for their company for the portable repeater that listed the wideband 5khz emissions designator (16K03FE), even though the programming software and literature for the radio clearly let you set Wideband or Narrowband.

In fact, I checked a bunch of their other GMRS transceivers and none of them appear to have the wideband emissions designator grant, only narrow.

 

Very interesting!  How did you look up the FCC grants for the various devices?  

[aa7jc]

I googled the code from the back of my KG-935G (wvtwouxun26) and was able to zero in to an FCC site fccid.io.

The test report is this  https://fccid.io/WVTWOUXUN26/Test-Report/Test-Report-5372630

The screen shots below are samples in that report of the audio response and the deviation response for both the wide and narrow sections of the GMRS band.

[colbypr]

I searched it on fccid.io. I also searched it directly through the FCC's website to confirm the information was correct. All you need is the FCC ID which is fairly easy to get. Its listed either on various websites or the retailer's sites. In the case of the RT97S, its listed directly on the mygmrs shopping page as a certified transmitter. It just doesn't seem right that its listed as both wide and narrow but the grant only specifies narrow.  All of the Wouxun GMRS radios I searched have both 11K03FE and 16K03FE emission designators in the grants, but none of Retevis GMRS stuff I searched did, even if it advertised it as narrow and wide capable.

The link direct to the FCC is here: https://www.fcc.gov/oet/ea/fccid

[aa7jc]

6 minutes ago, colbypr said:

I searched it on fccid.io. I also searched it directly through the FCC's website to confirm the information was correct. All you need is the FCC ID which is fairly easy to get. Its listed either on various websites or the retailer's sites. In the case of the RT97S, its listed directly on the mygmrs shopping page as a certified transmitter. It just doesn't seem right that its listed as both wide and narrow but the grant only specifies narrow.  All of the Wouxun GMRS radios I searched have both 11K03FE and 16K03FE emission designators in the grants, but none of Retevis GMRS stuff I searched did, even if it advertised it as narrow and wide capable.

The link direct to the FCC is here: https://www.fcc.gov/oet/ea/fccid

Thanks. 

I am reading through the report for the Retevis RT97S and just like you said it is 11K0F3E specific unless I am missing something...

Ken WQXQ522

 

 

!  

[colbypr]

Same information I found, which I found odd given its advertised as both narrow (2.5khz) and wide (5khz) capable. The programming software allows you to select narrow or wide, but no grant for 16K03FE emissions exists for this piece of equipment, regardless of the fact its sold as wideband capable.

[aa7jc]

The report I pulled up for the retevis RT97S was at https://fcc.report/FCC-ID/2ASNSRT97/4720800

On page 48 of that report it issued a bunch of "PASS" statuses for a test of 5kHz deviation..

The numbers there look like that radio reached close to the limit of 5kHz      ...No doubt I am missing something somewhere...

Ken

[wayoverthere]

First, I'll suggest not trusting those other sites ( .io or .report) 100%, as they aren't official sites and I've seen a few glitches in the data...though that doesn't seem to be the issue here.

Here is the actual doc on fcc.gov...looks like narrow only there...11k0f3e and 5 watts only.

https://apps.fcc.gov/oetcf/tcb/reports/Tcb731GrantForm.cfm?mode=COPY&RequestTimeout=500&tcb_code=&application_id=46EoA4PpE8zlyRIMY2v7uw%3D%3D&fcc_id=2ASNSRT97

Here is the main authorization search page https://apps.fcc.gov/oetcf/eas/reports/GenericSearch.cfm

Perhaps the "wideband" is there for ham use, where they aren't subject to certification testing like they are for gmrs?

 

[colbypr]

I thought it was odd too so I pulled the grant directly from the FCC and no wideband emissions designator.  You might be on to something though, re: amateur use.

 

[KAF6045]

Might be coincidental to them shipping with everything set to narrow band. If the testing agency doesn't dig deeper to learn how to change the default channels (being GMRS with just the 22 frequencies (pairs for the 8 used for duplex) they may have just tested on the presets.

 

[wayoverthere]

2 hours ago, aa7jc said:

The report I pulled up for the retevis RT97S was at https://fcc.report/FCC-ID/2ASNSRT97/4720800

On page 48 of that report it issued a bunch of "PASS" statuses for a test of 5kHz deviation..

The numbers there look like that radio reached close to the limit of 5kHz      ...No doubt I am missing something somewhere...

Ken

I forget the page number now, and I may be reading it wrong, but was the chart earlier in the report (page 15 or so?) focused on spurious emissions showing the spurs were higher output than the actual in band signal?

[KAF6045]

5 hours ago, KAF6045 said:

Might be coincidental to them shipping with everything set to narrow band. If the testing agency doesn't dig deeper to learn how to change the default channels (being GMRS with just the 22 frequencies (pairs for the 8 used for duplex) they may have just tested on the presets.

Worse than I thought -- the RA85s included in the package are old (non-user upgradable) firmware and locked to NFM. The upgraded firmware defaults to wide (normal) FM, and support named channels (the old firmware has menu options to change display between frequency and name, but doesn't seem to have a way to enter a name). Programming software seems incompatible as it has a column for name, which may be offsetting the channel data (I've tried with a BTech and Wouxun cable -- couldn't find a programming cable on Retevis site), and is flaky -- it isn't saving my edits to disk either!

Have a "contact" message submitted via their web site regarding how to get newer firmware in the RA85s -- none of my intended users (these would be loaners to "immediate family" during gatherings) would make sense of frequency displays -- being able to tell them to select "RT97 06" would be much easier. Also no spare batteries listed on the web site.

Even more worse: Channel slots 31-52 are locked as simplex; you can't even change the frequency. All you can do is set power, CTCSS or DCS tones.

Edited August 11, 2022 by KAF6045
simplex locked channels

[aa7jc]

3 hours ago, wayoverthere said:

I forget the page number now, and I may be reading it wrong, but was the chart earlier in the report (page 15 or so?) focused on spurious emissions showing the spurs were higher output than the actual in band signal?

The spurs are in section 5.9 starting on page 23.  I don't know,  I doubt it though since the radio got a "PASS". 
Hey thanks for the link on the GRANT..  It took me a while but I finally figured out what to click in their search results to see how you got it Lol!
This is a great thread.. lots of info.

Ken

[colbypr]

I had considered the RT97S simply because its a self contained unit and even with its low output power seems to do a great job with the components its assembled from as a whole. Not to mention, its advertised as having a part 95E grant.  There is plenty of legacy Motorola or other radios used as part of older part-90 systems, so I don't think its necessarily an issue, but the lack of a wideband emissions grant peaked my interest and wanted to see if anyone else had noticed it or possibly had an explanation.

I googled for hours and couldn't find anything on it. I found plenty of info specifying it was capable of Narrow or Wide emissions, but nothing indicating an actual grant existed anywhere or that anyone had discovered the same thing. Same with any other Retevis product.  I also found it interesting that buytwowayradios doesn't appear to sell anything marked Retevis for GMRS.

[wayoverthere]

IMO... I wouldn't let the narrowband only grant turn me away if it otherwise met my needs. The biggest issue of wideband vs narrowband is the equipment is mismatched (narrowband radio into a widband repeater, or vice versa). It would just come down to setting up the radios accordingly.

On another note, from what I saw on retevis' sitez the stock tuning for the original rt97 wants 10mhz offset in vhf or uhf...not even feasible in vhf (2m), being only 4mhz wide. It makes me wonder if the lower rated power on the gmrs model is to get it to sneak under the thresholds for certification (from some of the numbers we saw in the report), if it's accounting for signal loss tuning that tiny duplexer down to a 5mhz offset, or a bit of both.

[Ian]

On 8/11/2022 at 11:41 AM, wayoverthere said:

IMO... I wouldn't let the narrowband only grant turn me away if it otherwise met my needs. The biggest issue of wideband vs narrowband is the equipment is mismatched (narrowband radio into a widband repeater, or vice versa). It would just come down to setting up the radios accordingly.

On another note, from what I saw on retevis' sitez the stock tuning for the original rt97 wants 10mhz offset in vhf or uhf...not even feasible in vhf (2m), being only 4mhz wide. It makes me wonder if the lower rated power on the gmrs model is to get it to sneak under the thresholds for certification (from some of the numbers we saw in the report), if it's accounting for signal loss tuning that tiny duplexer down to a 5mhz offset, or a bit of both.

Yeah, it's due to the much higher insertion losses when their tiny duplexer is tuned for a 5 MHz offset, I believe.

I'm amazed they didn't check to see if the VHF unit was operating in anything like a usable band configuration, to be honest…

[wayoverthere]

1 hour ago, Ian said:

Yeah, it's due to the much higher insertion losses when their tiny duplexer is tuned for a 5 MHz offset, I believe.

I'm amazed they didn't check to see if the VHF unit was operating in anything like a usable band configuration, to be honest…

i know it throws out the "one box" nature of the RT97, but i wonder if one would see any improvement bypassing the built in duplexer in favor of one of the cheap flat pack "mobile" duplexers

[KAF6045]

11 hours ago, wayoverthere said:

i know it throws out the "one box" nature of the RT97, but i wonder if one would see any improvement bypassing the built in duplexer in favor of one of the cheap flat pack "mobile" duplexers

Just for my education -- do you have a link to one (or more) of those units?

The closest things I've seen to "flat pack" are the /diplexers/ used to combine separate VHF&UHF sources into one (my TS-2000 has dual-HF, separate VHF & UHF -- needs a diplexer to combine the VHF&UHF to feed a dual band; my previous vehicle rig [FT-100] had combined VHF/UHF and separate HF -- needed a different diplexer to combine for the ATAS-100 screwdriver antenna).

 

[wrci350]

17 minutes ago, KAF6045 said:

Just for my education -- do you have a link to one (or more) of those units?

Search on eBay for "repeater duplexer" and you'll see lots of them.

[wayoverthere]

2 hours ago, KAF6045 said:

Just for my education -- do you have a link to one (or more) of those units?

I've always seen them referred to by that term, maybe I'm missing it. Here is one of the first results from a quick Google:

https://www.amazon.com/Fumei-400-470MHz-Duplexer-Frequency-connectors/dp/B07FGFX6Q4

[KAF6045]

1 hour ago, wayoverthere said:

I've always seen them referred to by that term, maybe I'm missing it. Here is one of the first results from a quick Google:

https://www.amazon.com/Fumei-400-470MHz-Duplexer-Frequency-connectors/dp/B07FGFX6Q4

No.. That qualifies as an "in band" duplexer... vs what I was describing (HRO seems to catalog them as duplexers, but I've seen diplexer used for the cross-band systems) https://www.hamradio.com/detail.cfm?pid=H0-001449 (HF & VHF/UHF) https://www.hamradio.com/detail.cfm?pid=H0-001446 (2m & 70cm)

[wayoverthere]

2 hours ago, KAF6045 said:

No.. That qualifies as an "in band" duplexer... vs what I was describing (HRO seems to catalog them as duplexers, but I've seen diplexer used for the cross-band systems) https://www.hamradio.com/detail.cfm?pid=H0-001449 (HF & VHF/UHF) https://www.hamradio.com/detail.cfm?pid=H0-001446 (2m & 70cm)

I mistyped above... should have been "misusing", not "missing", as in misusing the "flatpack" moniker.

I've always thought of the dUplexers as being for in band stuff, and the dIplexers as being for splitting or combining 2 bands (the "di" part), though I know the terms get used interchangeably.  I'm running one of the latter in my ham base setup to feed 2 single band vertex decks into one dual band comet antenna.