| HN Mirror

That baofeng isn’t full duplex, they’re using an incorrect definition. It can’t transmit and receive simultaneously on different bands.

mindcrime 2104 days ago

Fair enough. I was just thinking in terms of the "not walking on people" thing... to achieve that you don't really need "true" full duplex, you just need the ability to configure a cross-band channel. Sure, there's a race condition if two people start transmitting at nearly the exact same instance, but in practice that doesn't seem to be a big problem.

Do you work satellites?

It's a really big problem-- people who can't hear whether and how well they're getting in, interfering with people who are.

There's often dozens of people contending for time on a little 7 minute pass. A QSO finishes and everyone keys at once to get in. Someone has bad doppler correction on the uplink and isn't making it in and you can't really tell who it is or tell them. Someone else with a PL tone mistake jams everyone. Someone else can't get through well enough to be intelligible, but still can cause big QRM and confusion for everyone else (is that someone answering? is that person successfully having a QSO and -I- am hearing badly?).

Just about every radio will do what you describe. You don't -want- a cross-band channel usually, because you want to tune separately for TX and RX. (I've also done it where you make many, many channels with pairs of uplink and downlink frequencies).

With real full duplex, satellite is, say, 5x easier -and- you stop being disruptive to other users of the sat.

mindcrime 2103 days ago

Do you work satellites?

I'm just getting started in this world.

A QSO finishes and everyone keys at once to get in.

Aaah, interesting. I've never been around one of those situations and it never occurred to me that enough people would be doing something this niche at one time for that kind of jam-up to occur.

Thanks for the heads-up. I guess maybe I'll look at investing in a real full-duplex radio at some point. Probably a mobile though, not an HT. Getting a decent mobile rig for my truck is next on my ham wish-list anyway.

The experience operating sats is very different depending on where you are on the globe. Advice that's okay in one place may be bad advice in a different location.

One final heads-up, the vertical antennas typically fitted to vehicles make really poor satellite antennas because you can easily emit enough power to make it into the sat, but there isn't enough directional gain to hear the downlink, so you're back in the same situation. A dual band yagi antenna really is the way to go. You also don't want to use a mobile radio with a yagi unless it's turned down to low power, because of RF exposure limits at VHF/UHF. A typical portable station is a dual band yagi (e.g. Arrow II) with one FD or two HD handheld radios, a headset, and a voice recorder, and a typical fixed setup is az-el rotator with computer control, dual circularly polarised X-quad yagis, masthead preamplifiers, and Doppler control of uplink and downlink frequencies.

mlyle 2103 days ago

Satellites are a ton of fun! You should go for it. You -don't- need a full duplex radio to get started. It just helps and makes it easier for everyone else, too.

If you decide to... it's important to just plan to listen to a few passes and get to hearing the satellite really well before you try to transmit, though.

Yes, you absolutely do need true full duplex to (a) know you're getting in, (b) not step on anyone else, (c) know when you're being stepped on, all of which are really required to operate effectively and courteously.

mlyle 2101 days ago

Let's not excessively gatekeep things. Someone who is curious and wants to try a satellite once shouldn't need to buy new equipment. A dumb HT with a simple whip is enough; just keep your transmit duty cycle low and try hard to not step on people.

If I followed this advice a couple decades ago I'd never have gotten into operating sats. Yes, now that I'm equipped for FD I'd never operate without it, but..

Not full duplex. Only "cheap" option is Wouxun KG-UV8D; only OTHER HT option I know is Kenwood TH-D72A.

entropea 2103 days ago

Alinco DJ-G7T has real full duplex.

Kenwood TH-D7

Fancy-pants cross-band full duplex can be achieved with two £15 Baofeng UV-5Rs and a DIY duplexer with about 2 components on it (or just two antennas on one boom).

That's my setup - I'm not better equipped than that.

dx4100 2104 days ago

My cheapest HT can do this. And my 20 year old radio can do it. So not sure about "exotic"

Dual watch, or full duplex?

My decades-old FT-470 can do true full duplex too, but it's less common in current radios. Just dual watch now.

I don't know of anything except Wouxun Dual and TH-D72 that can do it (that are HTs).

If a D72 is your cheapest HT, then well, congrats.

jimnotgym 2104 days ago

What radios are they?

Kenwood's TH-D72, TH-V71A, and TM-D710G can do it.

An incomplete list of full duplex vhf/uhf cross-band FM radios can be found in this reddit comment: https://www.reddit.com/r/amateurradio/comments/97jhik/gettin...

TM-V71A isn't a HT, nor is a TM-D710G. For a new ham who's scraped together some coins and gotten an HT, the only options that I'm aware that will work are the TH-D72.

AFAIK the only options are TH-D72 and Wouxun Dual.

While not an HT, the TM-V71A is very popular for LEO usage because you can easily ramp up to 25W when needed.

See this video of John Brier KG4AKV with his front-backpack TM-V71A mount. https://www.youtube.com/watch?v=w7Ukh_nT2Tg

jimnotgym 2104 days ago

Sure they can, but I wondered what cheap radio the OP was talking about that runs full-duplex?

Yeah, there really aren't any. The cheapest option is two unwieldy independent Baofengs.

A second-hand Kenwood TH-D7 is an alright choice.