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AT-778


Hasaf
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I have seen several mentions of the AT-778uv, but not of the AT-778, which is a different radio. It is a lot like the Midland MXT275 with a couple of differences. The first difference is that the power is claimed to be 25W, rather than Midlands 15W max output. Another difference is that the AT-778 has  a large power switch on the radio chassis. How useful that power switch really is can be seen as a bit questionable unless the radio chassis is mounted in an easily accessible location, negating the value of a "controls on the microphone" style radio in the first place.

I haven't done any meaningful testing on it yet, other than basic power-up and radio checks. It does not come with the programming cable. However, once I figured out the basics, it was easy, if tedious, to program. This is a Part 90 radio, so it will need to be programmed. Frankly, if I had noticed that it was Part 90 before I purchased it, I probably would have just gone with the Midland.

The bandwidth can be changed for individual channels. However, the lowest power it can be set to is 5W, putting it out of specification for channels 8-14. I am a bit concerned that it may be too easy to change the programming. I have yet to bump-program any of my settings, but it looks like it would be easy to do on accident.

GMRS-under-seat.jpg

Here it is, mounted under the passenger seat of an FJ Cruiser. The unit next to it is my VHF/UHF Kenwood.

GMRS-microphone.jpg

Here is the control/microphone

 

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Is that an actual switch for on/off, rather than a power button

It is a switch.

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If so, I could see just leaving it on, and wiring it behind a relay that shuts off when the key is turned off, or a keyed 12v socket)

That is what I have done, both it and the 2m/440 are wired to a relay after the accessory circuit. As such, they turn on and off with the car. As for the switch on the radio, I just leave it on.

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47 minutes ago, Hasaf said:

It is a switch.

That is what I have done, both it and the 2m/440 are wired to a relay after the accessory circuit. As such, they turn on and off with the car. As for the switch on the radio, I just leave it on.

Nice!👍 I converted one of my always-on 12v receptacles to keyed and do the same with my mxt115 (when it's hooked up....i swap between that and using a  HT for 70cm).

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19 minutes ago, axorlov said:

I'm looking for something like MTX 275 or this one for the installation in a small car. FCC ID?

FCC ID T4KAT778U

I have today off, so I spent a couple of hours pulling the headliner and installing a couple NMO connectors, then running the coax behind stuff until they get to the radios. Probably the only smart thing I did was to label the coax "front" and "rear" so I can remember which piece goes to which mount.

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Hasaf,

I have a 2m mounted in my FJ. I took the head liner down enough to use marine epoxy to a attach a piece of hardwood 2x4 to the roof and install an NMO. I put the headliner back up and mounted the radio mount to the 2x4. The radio has been mounted that way for 9 years of pretty heavy off road use. I never thought about under the passenger seat. Which brings up another point: It is disturbing how clean it is under your seats!

Sean 

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On 7/14/2021 at 3:46 PM, Hasaf said:

FCC ID T4KAT778U

I have today off, so I spent a couple of hours pulling the headliner and installing a couple NMO connectors, then running the coax behind stuff until they get to the radios. Probably the only smart thing I did was to label the coax "front" and "rear" so I can remember which piece goes to which mount.

Based on this FCC ID, its is narrow band only 10kHz, and not approved (or can't do) 20kHz wideband.

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Sorry it has taken me so long to finish this. The frequencies were programmed from this chart. I have not confirmed the Frequency counter. However, I have not adjusted it either. If it is to be trusted, this radio is transmitting a bit off frequency on Channel 20. The Channel 5&12 frequencies may be a rounding error. According to the manual, both the receiver and the transmitter are capable of both narrow and wide band. However, I do not have the means of testing this.

More troublesome is the low power output. The specifications claim 25W at full power. the test showed 17.77W. At low power the specifications claim 5W and the meter showed 4.28W. Ignore the SWR, I am using a Midland MXTA26 and it is ~1:1 on channel 12, but falls off, pretty quickly, on both sides.

On Channel 20

GMRS-20-radio.jpg

GMRS-20-Meter.jpg

 

On Channel 5

GMRS-5-Radio.jpg

GMRS-5-Meter.jpg

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What you have to remember, the published power is really a target power in the programming, and there is almost always a curve or linear relationship to actual power output across the frequencies covered. Usually, the power is within 10% of the published number. 

The transmitter report showed 42W output for the "full power" version, assuming full power is 45W, that means it was 93% of the published output. This was at 400MHz, and could be better/worse along the UHF band.

Take your 5W target and you get 4.65, then take 95% of that for SWR loss and you get 4.4W, not too far off of the meter 4.3W output. Do the same for your CH20, 93% of 25W is 23.25W, then take 89% of that gives you 20W output, close to your meter output.

Could there be a minor calibration that is off, or the meter is 10% off? Sure. What I would take away from it is what is your "normal" and see when things change.

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It also shows more reflected power on highpower. at that point the meter reading is not as accurate. If this is in a dummy load then its bad. If its in the antenna I'd find a dummy load. A $100 meter will be around 10% as said above and looks accurate

 

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On 7/27/2021 at 10:27 AM, kb2ztx said:

It also shows more reflected power on highpower. at that point the meter reading is not as accurate. If this is in a dummy load then its bad. If its in the antenna I'd find a dummy load. A $100 meter will be around 10% as said above and looks accurate

 

No, it was an antenna. I wrote to Midland about it and they responded with, what amounted to, "the antenna is working fine."

Mostly my post is because this radio didn't seem to be mentioned here, so I was trying to give potential users some idea of what it was and how well it performed. As I understand, Midland is coming out with a full power unit, with the controls on the microphone, soon. I will probably go that route when they do.

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