At the RepeaterBook.com lab, we tested the SWR of the Diamond MR77 antenna using the RigExpert AA-1000. According to Diamond, the antenna is a mag mount 1/4-wave on 2-meters and a 5/8-wave on 70-centimeters. The gain is reported as 2.15 dBi on 2-meters and 3.4 dBi on 70-cm. It can handle 70 watts of power with an overall length of 20 inches. It comes in both UHF and SMA configurations. We tested the UHF version.
We tested the antenna on a cookie sheet and attempted to adjust the antenna length to the best possible SWR. Your results may vary.
2-meter Band
| Frequency | SWR |
| 144.000 | 2.0 |
| 145.000 | 1.9 |
| 146.000 | 1.9 |
| 147.000 | 1.8 |
70-centimeter Band
| Frequency | SWR |
| 430.000 | 2.2 |
| 435.000 | 1.9 |
| 440.000 | 1.9 |
| 445.000 | 1.5 |
| 449.000 | 1.23 |
GMRS
| Frequency | SWR |
| 462.000 | 1.34 |
| 467.000 | 1.42 |
33-centimeter Band
This antenna is not specifically sold as a 33-cm band antenna, but it is well-tuned.
| Frequency | SWR |
| 902.000 | 1.8 |
Verdict
This antenna did not perform well enough to consider it for a radio station that will just be transmitting on the 2-meter and 70-centimeter bands. SWR should under 1.5 on the frequencies primarily be used. However, if you are looking for an antenna that will work on both the 2-meter and 70-cm bands along with GMRS, this antenna performed very well on the GMRS frequency range and could be an excellent middle-of-the-road antenna for that. The bonus is the performance in the 33-centimeter band.
This antenna is priced just a bit cheaper than Comet antennas, but the Comet antennas seem to perform a little better for the money.
We will re-run these tests with the antenna mounted to a vehicle and report back on the results.