DB20-G as a Repeater

[WRYI436]

Hello Newbi here

Is there a way to connect 2 DB20-g's together through the mic port to use them as a repeater? Can the wiring be reconfigured using a patch cable to activate the TX to transmit from the RX radio, along with the speaker to mic connections? Or would this need a special controller in between to do the work?

[SteveShannon]

1 minute ago, WRYI436 said:

Hello Newbi here

Is there a way to connect 2 DB20-g's together through the mic port to use them as a repeater? Can the wiring be reconfigured using a patch cable to activate the TX to transmit from the RX radio, along with the speaker to mic connections? Or would this need a special controller in between to do the work?

It should be possible, but it’s not nearly as simple as you describe. You would need a repeater controller. The ID-o-matic should work. 
You would also need a duplexer and of course cables and an antenna. 
However, people have tried doing things like that before and found that the receiver half desensitizes itself. The solution to that is shielding and/or distance. 
Be prepared for a lot of experimentation. Some of us enjoy that. 

[Borage257]

I’m interested in this. How does the receiver desensitize it’s self if you are using a duplexer?

[SteveShannon]

57 minutes ago, Borage257 said:

I’m interested in this. How does the receiver desensitize it’s self if you are using a duplexer?

The duplexer doesn’t shield against RF getting into the case. It only filters to prevent the RF from the transmitter from entering via the antenna port on the receiver. 
You might expect that the metal chassis provides a shield, and to some extent it probably does, but every wire that enters the case can function as an antenna, whether it’s the power cable or microphone.

So, like I said, I suspect that some experimentation will be required. Maybe it’ll work; maybe it won’t. 

[OffRoaderX]

I put together a repeater with two KG1000G radios, and desense was a real issue, even after separating the radios by about 10 feet and adding makeshift shielding.

[Borage257]

I expect keeping the wires at non-resonant lengths and adding lots of ferrite beads would help. I wonder if putting each radio in its own metal enclosure (30cal ammocan?) would help. 

[marcspaz]

Same here. I use 2 radios for my amateur repeater. The radios are RF linked and the up-link and down-link are separated as much as 1/2 mile depending on use case and how much power the transmitter needs to be. I found that even at 5 watts, I need about 100 feet of separation.

 

Cable-linking introduces a whole new level of aggravation. Depending on your use case, it may be easier and more affordable to simply by a low power repeater. 

[SteveShannon]

31 minutes ago, OffRoaderX said:

I put together a repeater with two KG1000G radios, and desense was a real issue, even after separating the radios by about 10 feet and adding makeshift shielding.

And those are specifically sold as having the capability of being joined together as a repeater.  

[K7lon]

Interference is a problem when trying to build a diy repeater.

You might be able to build a patch cord with a control curcit in the middle. However it is a hevey lift unless you have guru status. I built a repeater with two Midland data radios, burned up two radios, tried different types of radios, controller's, cheap duplexer, Celwave duplexer, many hours, lots of dollars ($1,000 plus). I tell myself it was fun?

A Midland or Retevis repeater would be quicker, cheaper, and possibly more efficient.

Just a thought from a hobbyists. 

Good luck on your journey. 

 

WRJA397

 

[WRYS709]

On 8/22/2023 at 8:23 PM, WRYI436 said:

Hello Newbi here

Is there a way to connect 2 DB20-g's together through the mic port to use them as a repeater? Can the wiring be reconfigured using a patch cable to activate the TX to transmit from the RX radio, along with the speaker to mic connections? Or would this need a special controller in between to do the work?

The problem with using the DB20-G to build a repeater is what is called “Duty Cycle.” In the design and engineering of a transciever they decide the average time that the unit will be in “transmit” (especially on HIGH power) as compared to “receive” and then using this percentage they design the needed heat sinks to to disapate the heat away from the chips generating the heat.

 

The DB20-G, like most transceivers at this price range, will get extraordinarily hot when left on transmit on HIGH for long periods of time and of course, by its very nature, the radio used in a repeater to retransmit received transmission will be on transmit for a much longer period of time that was designed and engineered into the radio.