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Author Topic: RTS / Telex BTR-800 Wireless com  (Read 1318 times)

Al Rettich

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RTS / Telex BTR-800 Wireless com
« on: June 20, 2017, 02:23:21 pm »

Is anyone still using the BTR-800's? Wondering if Telex's are going to offer a rebranding of frequencies? Anyone hear of anything?
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Pete Erskine

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Re: RTS / Telex BTR-800 Wireless com
« Reply #1 on: June 20, 2017, 03:01:13 pm »

Is anyone still using the BTR-800's? Wondering if Telex's are going to offer a rebranding of frequencies? Anyone hear of anything?

BTR's are at end of life.  I do not believe they are making them any more or will soon stop completely.  Also in any case their RF sections cannot be refreqed to do more than 2 bands below 600, 88 and 99. 

Best thing for all users is to sell them now to some other country which is not yet selling off bandwidth.

Many parts of the USA will have T-Mobile using their purchased 600 MHz by the end of this year.  Major markets like NY and LA in a couple of years.

See this chart - nothing in shaded ares can be used very soon.
« Last Edit: June 20, 2017, 03:22:49 pm by Pete Erskine »
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Pete Erskine
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Al Rettich

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Re: RTS / Telex BTR-800 Wireless com
« Reply #2 on: June 20, 2017, 05:08:53 pm »

Sounds like getting the retro mod that Professional Wireless does is useless as well..
My boss is going to be pissed...
BTR's are at end of life.  I do not believe they are making them any more or will soon stop completely.  Also in any case their RF sections cannot be refreqed to do more than 2 bands below 600, 88 and 99. 

Best thing for all users is to sell them now to some other country which is not yet selling off bandwidth.

Many parts of the USA will have T-Mobile using their purchased 600 MHz by the end of this year.  Major markets like NY and LA in a couple of years.

See this chart - nothing in shaded ares can be used very soon.
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Ike Zimbel

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Re: RTS / Telex BTR-800 Wireless com
« Reply #3 on: July 09, 2017, 10:56:11 am »

Sounds like getting the retro mod that Professional Wireless does is useless as well..
My boss is going to be pissed...
Full disclosure: I am the Canadian Manufacturer's rep for Radio Active Designs (aka Rad Com). That said, since many of you are in the States, I will press on...
If you are looking to replace BTR systems more-or-less "in kind" you could do worse than look at RadCom. The form factor is basically the same, the i/o is the same (give or take a few BNC-TNC adapters) or better (Ethercon (TM) connectors for the 4-wire instead of RJ-11), the biggest change will be switching to a VHF receive antenna.
On top of that there are some +'s, like the fact that all belt packs and all base stations are compatible...no more band splits. I know that I have on many occasions had to exchange (and re-coordinate...) an entire BTR system for one in a different band split just because one belt pack was bad and the supplier didn't have a spare in that band.
I could go on...
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~Ike Zimbel~
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Pete Erskine

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Re: RTS / Telex BTR-800 Wireless com
« Reply #4 on: July 09, 2017, 11:26:52 am »

On top of that there are some +'s, like the fact that all belt packs and all base stations are compatible...no more band splits. I know that I have on many occasions had to exchange (and re-coordinate...) an entire BTR system for one in a different band split just because one belt pack was bad and the supplier didn't have a spare in that band.
I could go on...

I agree with Ike... the Rad UV-1g system is really very good.  I've used it on a few shows and been very happy.  Since it's initial introduction any complaint users have had has quickly been met with software and hardware updates and now the system is very stable and more than a perfect replacement for the disappearing BTR. 

A huge plus which was not mentioned is that the bandwidth needed for frequencies is very small and many more channels can be found in the same space than with BTR.
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Pete Erskine
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Jason Glass

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Re: RTS / Telex BTR-800 Wireless com
« Reply #5 on: July 09, 2017, 01:01:18 pm »

A huge plus which was not mentioned is that the bandwidth needed for frequencies is very small and many more channels can be found in the same space than with BTR.

Agreed. You can cram all of your base station TX into a small bandwidth and set up guard bands on each side, equal in width to the distance between the highest and lowest base freqs, which will contain most of their intermod products. This is especially helpful when operating at 100mW or at 250mW under part 74 rules.

Speaking of licensed use, UV-1G base stations will TX 250mW and require no mods for properly splitting and combining signals. I routinely cover entire stadiums and festival grounds with a single antenna mounted high up.

While their TX-8 is a killer unit (for IEM, too!), you can utilize your current stock of IEM combiners for base station use and save a few $.

Up to 100mW:
Shure PA821, PA821A, PA421A
Sennheiser ACA-3000

Up to 250mW
RAD TX-8
Sennheiser ACA-3200
PWS GX-4, GX-8 (100mW in, 250mW out)

EDIT: PLEASE SEE HENRY'S POST BELOW ABOUT WHY MY IEM COMBINER ADVICE MAY BE NOT SO GOOD.

The RX side requires a VHF antenna and splitting equipment such as the RAD V-8 or PWS DB-IC-V series. A major bonus of VHF is much lower loss per foot of coax. FYI, the new Shure UA860V is an excellent remote VHF omni antenna and is remarkably compact.

Advanced users and integrators will like that the system's VHF/UHF RX/TX scheme places RX and TX bands far enough apart to use inexpensive filter-type diplexing for single cable runs to remote antenna pairs.

Rave complete.  :-)

Sent from my Nexus 5 using Tapatalk
« Last Edit: July 11, 2017, 11:01:29 am by Jason Glass »
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Henry Cohen

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Re: RTS / Telex BTR-800 Wireless com
« Reply #6 on: July 09, 2017, 09:01:03 pm »

While their TX-8 is a killer unit (for IEM, too!), you can utilize your current stock of IEM combiners for base station use and save a few $.

RAD does not recommend using a transmit combiner for the UV-1G base other than the TX-8. The reason (no, it's not just to sell more product) is that because of the dual sideband nature of the carrier (essentially two carriers per channel), it was found the intermod suppression of the other [very good] products was insufficient when the base is run at more than 20mW/ch. That said, YMMV and if another make/model combiner is working for you, then continue using it. At this point, there appears to be no danger to the base transmitter stages.

And thank you Jason, and Pete, for your kind words and support of RAD.
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Henry Cohen

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Jason Glass

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Re: RTS / Telex BTR-800 Wireless com
« Reply #7 on: July 11, 2017, 10:55:31 am »



RAD does not recommend using a transmit combiner for the UV-1G base other than the TX-8. The reason (no, it's not just to sell more product) is that because of the dual sideband nature of the carrier (essentially two carriers per channel), it was found the intermod suppression of the other [very good] products was insufficient when the base is run at more than 20mW/ch. That said, YMMV and if another make/model combiner is working for you, then continue using it. At this point, there appears to be no danger to the base transmitter stages.

And thank you Jason, and Pete, for your kind words and support of RAD.

Thank you for this clarification! It's been a year or two since I used an IEM combiner for RAD TX, and on all occasions it was only one or two PL channels added to an existing IEM rig with spare inputs. I recall occasionally having less than stellar audio, but it was passable and I (perhaps wrongly) attributed it to gain staging issues that have since been corrected in the firmware.

Am I correctly assuming that the DSB modulation scheme's AM nature requires gobs of headroom to avoid amp compression?  It seems that this could particularly make the GX series, having AGC, particularly damaging to the signal.

Sent from my Nexus 5 using Tapatalk

Cameron Stuckey

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Re: RTS / Telex BTR-800 Wireless com
« Reply #8 on: July 11, 2017, 05:20:29 pm »

Am I correctly assuming that the DSB modulation scheme's AM nature requires gobs of headroom to avoid amp compression?  It seems that this could particularly make the GX series, having AGC, particularly damaging to the signal.

Speaking for Professional Wireless, you cannot put the UV-1G into the GX series. The AGC circuit constantly chases the AM signal trying to compensate for the modulation. This directly impacts audio quality of the system. The GX series was designed for fixed amplitude signals, e.g. FM.

Cameron
Professional Wireless
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Jason Glass

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Re: RTS / Telex BTR-800 Wireless com
« Reply #9 on: July 11, 2017, 05:28:51 pm »

Speaking for Professional Wireless, you cannot put the UV-1G into the GX series. The AGC circuit constantly chases the AM signal trying to compensate for the modulation. This directly impacts audio quality of the system. The GX series was designed for fixed amplitude signals, e.g. FM.

Cameron
Professional Wireless
Thanks, Cameron. I was worried that this would be the case. It must have an extremely fast limiter!

Sent from my Nexus 5 using Tapatalk

Jason Glass

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Re: RTS / Telex BTR-800 Wireless com
« Reply #10 on: July 27, 2017, 06:13:50 pm »

Speaking for Professional Wireless, you cannot put the UV-1G into the GX series. The AGC circuit constantly chases the AM signal trying to compensate for the modulation. This directly impacts audio quality of the system. The GX series was designed for fixed amplitude signals, e.g. FM.

Cameron
Professional Wireless
Hey, Cam

Just for giggles, we tested 2 channels of Lectro Duet through a GX-8 today and got interesting results. At all three Duet power levels, the combiner added 6 sidebands to the carrier, distorting the 200kHz channel bandwidth to 1.4MHz. Yeow! Strangely, switching from normal to high power on the GX had no measurable effect whatsoever on the amplitude or spectral shape. Even more strangely, the system still functioned fine and walk testing showed the range to be commensurate with 10mW output routed directly from the Duet to the same test antenna.

Of course I know that these were severe experimental conditions well outside of design tolerances and intended use, but I didn't expect the system to work as well as it did with AGC trying to squash AM.

Giggles we wanted, and giggles we got!

EDIT, CORRECTIONS:

The number of distortion sidebands that we measured was actually 4, not 6, and their bandwidth was around 125kHz, not 200 kHz, making the total distorted channel bandwidth near 700kHz, not 1.4MHz.  Uugh.

10mW input actually generated less distortion and its output power within a 200kHz channel mask was around 3dB lower than 25mW and 50mW input levels, as one might expect.  However, 50mW input pushed power to the outer sidebands and the channel power was slightly lower than 25mW, as one might expect from a saturated amp.

Since the Devil's in the details, my post above was quite incorrect and I apologize for causing confusion.

« Last Edit: July 28, 2017, 12:34:56 pm by Jason Glass »
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Cameron Stuckey

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Re: RTS / Telex BTR-800 Wireless com
« Reply #11 on: July 27, 2017, 08:47:39 pm »

...    At all three Duet power levels, the combiner added 6 sidebands to the carrier, distorting the 200kHz channel bandwidth to 1.4MHz.    ...   Even more strangely, the system still functioned fine and walk testing showed the range to be commensurate with 10mW output routed directly from the Duet to the same test antenna.

To confirm, you experienced that distortion and distances with 10mW direct and 10mW into the GX? Spec for the input power of a GX is 20mW-100mW. If the Duet was at 10mW into the GX I'm not surprised things got a little funky.
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Jason Glass

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Re: RTS / Telex BTR-800 Wireless com
« Reply #12 on: July 27, 2017, 09:07:41 pm »

To confirm, you experienced that distortion and distances with 10mW direct and 10mW into the GX? Spec for the input power of a GX is 20mW-100mW. If the Duet was at 10mW into the GX I'm not surprised things got a little funky.
The spectral signature and amplitude from the GX-8 output were identical with input signal strengths of 10mW, 25mW, and 50mW.

EDIT, CORRECTIONS:

The number of distortion sidebands that we measured was actually 4, not 6, and their bandwidth was around 125kHz, not 200 kHz, making the total distorted channel bandwidth near 700kHz, not 1.4MHz.  Uugh.

10mW input actually generated less distortion and its output power within a 200kHz channel mask was around 3dB lower than 25mW and 50mW input levels, as one might expect.  However, 50mW input pushed power to the outer sidebands and the channel power was slightly lower than 25mW, as one might expect from a saturated amp.

Since the Devil's in the details, my post above was quite incorrect and I apologize for causing confusion.
« Last Edit: July 28, 2017, 12:35:53 pm by Jason Glass »
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Henry Cohen

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Re: RTS / Telex BTR-800 Wireless com
« Reply #13 on: July 28, 2017, 11:31:57 am »

The spectral signature and amplitude from the GX-8 output were identical with input signal strengths of 10mW, 25mW, and 50mW.

I'm not surprised either. I would presume the composite energy from the 8PSK carrier, even at the 10mW setting, is close enough to that of a 100mW FM CW carrier such that not only is there no defined [relatively] narrow band carrier for the AGC to lock on to, but the amplifier stage is in saturation from the start.
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Henry Cohen

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Jason Glass

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Re: RTS / Telex BTR-800 Wireless com
« Reply #14 on: July 28, 2017, 12:32:34 pm »

I'm not surprised either. I would presume the composite energy from the 8PSK carrier, even at the 10mW setting, is close enough to that of a 100mW FM CW carrier such that not only is there no defined [relatively] narrow band carrier for the AGC to lock on to, but the amplifier stage is in saturation from the start.

Understood.  BTW, I must make some corrections below about the details, as my memory fuzzed badly when I posted. I went back and compared SA screen shots of the different test conditions, which I have attached to this post.

The number of distortion sidebands that we measured was actually 4, not 6, and their bandwidth was around 125kHz, not 200 kHz, making the total distorted channel bandwidth near 700kHz, not 1.4MHz.  Uugh.

10mW input actually generated less distortion and its output power within a 200kHz channel mask was around 3dB lower than 25mW and 50mW input levels, as one might expect.  However, 50mW input pushed power to the outer sidebands and the channel power was slightly lower than 25mW, as one might expect from a saturated amp.

Since the Devil's in the details, my post above was quite incorrect and I apologize for causing confusion.  I'll go back and add these corrections as an addendum to the post.

I'm still stunned that the system sounded fine under these conditions.  In fact we pushed the limits and tuned two channels at 200kHz spacing (Lectro recommends no less than 400kHz), through a PA821A, and the audio didn't even slightly glitch.  I'd very much like to test 24 mixes of these working together!
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