Retevis RT97 Portable Repeater

[SteveSimpkin]

I haven't seen any posts about this product yet. The Retevis RT97 is a 10W duplex repeater with a pre-tuned duplexer in a weather resistant metal enclosure. It runs on 12V and sells for around $400 US. It can be ordered with a 5 MHz offset within the 420-450 MHz 70cm ham band. As such it should be useful as a low power ham repeater operating off of a single antenna. I don't think it is legal to use in the US for any other purpose as I can't find any FCC certification for it.
More information is available at the following websites.
RT97 Portable Repeater Power Amplifier UHF

 

[RFI-EMI-GUY]

This kills the deal unless you are on the left coast where folks use the reverse split on some UHF repeaters.

4, UHF-5Mhz-Customize: Offset 5mhz, Tx and Rx's frequencies can be customized. But Tx must be higher than Rx

 

[SteveSimpkin]

This kills the deal unless you are on the left coast where folks use the reverse split on some UHF repeaters.

4, UHF-5Mhz-Customize: Offset 5mhz, Tx and Rx's frequencies can be customized. But Tx must be higher than Rx

Definitely an inconvenience. Of the 15 70cm repeaters near me, 10 have a -5 MHz and 5 have a +5 MHz offset. I suspect there are other limitations that are more serious.

 

[RFI-EMI-GUY]

Definitely an inconvenience. Of the 15 70cm repeaters near me, 10 have a -5 MHz and 5 have a +5 MHz offset. I suspect there are other limitations that are more serious.

I always attributed the weird California offset to the availability of many obsolete UHF MTS and IMTS phones that could be easily converted to a repeater but stuck with the TX high.

 

[KK6ZTE]

I always thought it was because the ex-commercial subscriber gear RX side wouldn't go too far out of band but the TX side would?

 

[rescuecomm]

Why a deal killer? It's for portable operation which implies temporary use on a short term basis. If we had 440 mhz radios back in the early 1990's, this would have been ideal when our ARES team worked a Triathlon in a rural area of upstate SC.

 

[mmckenna]

That's a cable TV amplifier case, still has the strand clamps at the top and says "Line Amplifier" on the front.
I guess they got a deal on surplus boxes.

I'd have to admit, I've thought of building projects inside those before.
Nice to see the CCR manufactures haven't embraced the N connector.

 

[SteveSimpkin]

A look inside:

 

[RFI-EMI-GUY]

Why a deal killer? It's for portable operation which implies temporary use on a short term basis. If we had 440 mhz radios back in the early 1990's, this would have been ideal when our ARES team worked a Triathlon in a rural area of upstate SC.

Its not a deal killer if you are OK with a repeater on a reverse split.

For the price you could build something DIY with some RF modules and a duplexer.

 

[nd5y]

This kills the deal unless you are on the left coast where folks use the reverse split on some UHF repeaters.

4, UHF-5Mhz-Customize: Offset 5mhz, Tx and Rx's frequencies can be customized. But Tx must be higher than Rx

In additon to that I read on another web site (don't know if it's true) that because of the cheap ass duplexer used the offset must be at least 10 MHz.

 

[SteveSimpkin]

There are several preset configurations, some of which have a 10 MHz offset. Others have a 5 MHz offset. You can also custom order an offset between 5 MHz and 10 MHz. See their website.

RT97 Long Range Full Duplex Mini Portable Repeater

Retevis RT97 Long Range Full Duplex Mini Portable Repeater, 10W Portable Analog Repeater UHF/VHF，Compact size and Easy to setup, Weather resistant design, accessories inclulding the AC Adapter and DC power plug, the high power is 10 watts, extend your handheld two way radios or mobile analog...

www.retevis.com

 

[N4GIX]

Having up to 16 programmable channels is a worthless "feature" since the duplexer can only be tuned to one set of frequencies!

The live demo is worth watching though:

 

[SteveSimpkin]

Having up to 16 programmable channels is a worthless "feature" since the duplexer can only be tuned to one set of frequencies!

According to them, you can operate +/- 1 MHz of the frequency the duplexer is tuned to. See:

Why RT97 repeater has 16 channels?

I am confused... I thought that a repeater with a duplexer was tuned to a fixed set of frequencies. How does your RT97 repeater operate on 16 channels and still use a duplexer? Thank You.Above is

blog.retevis.com

 

[N4GIX]

According to them, you can operate +/- 1 MHz of the frequency the duplexer is tuned to. See:

Why RT97 repeater has 16 channels?

I am confused... I thought that a repeater with a duplexer was tuned to a fixed set of frequencies. How does your RT97 repeater operate on 16 channels and still use a duplexer? Thank You.Above is

blog.retevis.com

I wrote the same at the video linked above's comments section. However the further one gets from the can's set notch, the poorer the performance, unless of course the duplexer is really crappy to begin with...

Even so, having the backwards split is illogical. I can see no reason why they cannot tune the transmitter and receiver to work as normally used.

 

[SteveSimpkin]

Even so, having the backwards split is illogical. I can see no reason why they cannot tune the transmitter and receiver to work as normally used.

I am wonding why they can't (or won't) tune it for the other direction. For reference of the 15 70cm repeaters near me, 10 have a -5 MHz and 5 have a +5 MHz offset.

 

[kayn1n32008]

Having up to 16 programmable channels is a worthless "feature" since the duplexer can only be tuned to one set of frequencies!

The live demo is worth watching though:

Entirely wrong.

I built and tuned a VHF portable repeater, that had 13channels, 153.xxx paired +5.26MHz. Worked fine with adequate isolation between receive and transmit.

I can think of an NXDN system that has 4 RF channels and is using a Q3330E duplexes to combine the RX multicoupler and TX combined to use a single antenna.

Please stop posting nonsense.

 

[kayn1n32008]

I wrote the same at the video linked above's comments section. However the further one gets from the can's set notch, the poorer the performance, unless of course the duplexer is really crappy to begin with...

Even so, having the backwards split is illogical. I can see no reason why they cannot tune the transmitter and receiver to work as normally used.

It is quite possible to have a a flat bottom notch, rather than a sharp ‘V’ and pass a fairly wide segment and not lose much isolation.

The best example I can describe is a common hampster application of using a 147MHz pair(147.000-147.3900 TX paired with 147.600-147.990 RX) and uses a second duplexer to couple an APRS I-gate or digipeater to a single antenna.

The duplexer used to combine the two systems to one antenna Hi side port is tuned to notch 144.39 and and pass the repeater pair. The Lo side port is tuned to notch the 615Khz needed for the repeater and pass 144.390. The combined port on the repeater duplexer is connected to the Hi port on the duplexer used to combine APRS. The APRS radio is connected to the Lo port and the combined port is connected to the Heliax headed to the antenna.

 

[N4GIX]

Entirely wrong.

Please stop posting nonsense.

Not "entirely wrong." I will agree that with a high quality duplexer and a flatter bottom notch such is possible, albeit still with some increasing amount of degradation the further one moves from the tuned center frequency.

CCD (Cheap Chinese Duplexers) have a very sharp and narrow peak at the notch frequency. Having tuned well over a hundred of them over the past few years, on both my IFR 1200 Super S and CT 3000B service monitors the best they could do is around -60 dB. These certainly not anywhere near Sinclair quality where -100dB is achievable.

Please do not be so patronizing and rude.

 

[kayn1n32008]

Not "entirely wrong." I will agree that with a high quality duplexer and a flatter bottom notch such is possible, albeit still with some increasing amount of degradation the further one moves from the tuned center frequency.

CCD (Cheap Chinese Duplexers) have a very sharp and narrow peak at the notch frequency. Having tuned well over a hundred of them over the past few years, on both my IFR 1200 Super S and CT 3000B service monitors the best they could do is around -60 dB. These certainly not anywhere near Sinclair quality where -100dB is achievable.

Please do not be so patronizing and rude.

The portable VHF repeaters I built were using a Sinclair duplexer, but it was a mobile duplexer. Nothing fancy like a resloc.

Do you think the notch is only 7.5Khz wide? It’s quite easy to build notches that are 150+KHz wide while meeting acceptable isolation specs. To say duplexers will only pass 1 frequency pair is absurd.

 

[mancow]

That's a cable TV amplifier case, still has the strand clamps at the top and says "Line Amplifier" on the front.
I guess they got a deal on surplus boxes.

I'd have to admit, I've thought of building projects inside those before.
Nice to see the CCR manufactures haven't embraced the N connector.

Any idea what model of amp to look for? It looks perfect for a pi-w MMDVM repeater. I already have one of those duplexers.