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6 votes
Accepted

Recomended coax for 100ft (2m/70cm)

According to this online coax loss calculator, the loss of 50 feet of new Belden 9258 RG-8X with an antenna with an SWR of 1.5 is 4.29 dB at 450 MHz (UHF), so the loss for 100 feet of the same coax ...
rclocher3's user avatar
  • 9,242
4 votes

Experiences on a 70 cm band shared with radiolocation service

Here in the US ham radio is only a secondary user of the 70cm band, with the primary user being military radar. That didn't stop ham operators from setting up hundreds of repeaters on the band. Back ...
rclocher3's user avatar
  • 9,242
4 votes

What gain and power are required for successful DX contacts on 2m/70cm bands in CW?

My experienses on 2 meters when I was living in southern Finland (near Helsinki). My Finnisf call sign was (and still is) OH2AXE. I did not have 70 cm equipment. Antenna: 2 x 2 stack of double hybrid ...
Jukka Siitari - SV9RMU's user avatar
4 votes
Accepted

What gain and power are required for successful DX contacts on 2m/70cm bands in CW?

I will talk about my experiences with 2m here - 70cm is similar, except (and anybody who knows better than me please correct me) there is no sporadic-E at all ever on 70cm. It all depends on ...
Scott Earle's user avatar
  • 4,619
3 votes

Experiences on a 70 cm band shared with radiolocation service

I'm from Serbia, and there we have radio-location service as secondary user in almost whole (both ham and commercial) 70 cm band. In practice, this means ground-based or space-based RADARs. Space-...
AndrejaKo's user avatar
  • 2,893
3 votes

Performance of 2M/440 Amateur magnet mount antenna with CB

The performance would be quite bad. A typical 19" dual-bander is 0.043 wavelengths long on the 11 meter band (when you want it to be around 0.25 wavelengths long). It's hard to really accurately ...
hobbs - KC2G's user avatar
  • 12.5k
3 votes

Is there a trick for reaching a repeater "through" terrain?

Reaching a repeater 30 miles (48 km) away with a mountain in between, with a handheld, sounds nearly impossible. Reaching a repeater 15 miles away with a ridge in the way with a handheld sounds very ...
rclocher3's user avatar
  • 9,242
3 votes
Accepted

Proper magnetic mount placement on roof

When dealing with UHF and VHF communications, height is often the determining factor of range for line of sight conditions. If there are obstructions that height cannot overcome, then more effective ...
Glenn W9IQ's user avatar
  • 18.6k
2 votes

Proper magnetic mount placement on roof

It's difficult to predict in the general case how a particular antenna placement will work because it's very sensitive to the particular geometry of the car. Most likely the center of the roof is just ...
Phil Frost - W8II's user avatar
2 votes

440 MHz repeater, how would I set one up?

So, what is a repeater? A repeater receives the signals (messages) sent from someone, and sends them again. That increases the reach of the original sender. So, why a duplexer? Strictly speaking, you ...
Marcus Müller's user avatar
2 votes

Dual-band rubber duck gain on 2m vs. 70cm

This is so dependent on the particular antenna, and rubber ducks are such compromise antennas anyway, probably the only way to get a useful answer is to do a shootout between specific antennas. ...
MoTLD's user avatar
  • 736
2 votes

Is it possible to determine if I'm adjusting gamma match in correct direction with an SWR meter and if yes, how?

Well, I'm a little out of my depth, but this does seem to have all the usual parts of a gamma match: the matching section hanging off the main loop is a balanced transmission line, and the part ...
Phil Frost - W8II's user avatar
2 votes

Website for satellite down/uplink frequencies and live footprint?

https://www.amsat.org/status/ will show you a list of birds and if there has been any activity reported during the last week. Reports are crowd-sourced, the page allows you to drill down into each ...
WH6A's user avatar
  • 21
2 votes

Is there a trick for reaching a repeater "through" terrain?

Regardless of where you live or what band you operate, the general rule is: "If you can't hear 'em, you can't work 'em." A secondary rule for repeaters is that if no one is there, it gets boring fast....
cmm's user avatar
  • 276
2 votes

Maximum occupied bandwidth and symbol rate for amateur satellites

The maximum rates for the US are as follows: Frequency Rate 2 Meters 19.6k 70 cm 56k >902MHz. None You can find a reference from the FCC, a copy of the relevant section here, and another ...
David Hoelzer's user avatar
  • 1,053
1 vote
Accepted

Does sporadic E apply to UHF?

In short, most likely no. According to this article at electronics notes: Sporadic E is used by radio hams on bands from about 24 or 28MHz up to 144 MHz and very occasionally 225 MHz in the USA. It ...
webmarc's user avatar
  • 4,241
1 vote

While backpacking, is it worth mounting the antenna to the backpack frame (above my head)?

If all your radios will near the same height (plateau) with nothing between them (like mountains), then the biggest limitation will be the curvature of the earth. With a 2m radio, this limits you to ...
user10489's user avatar
  • 6,485
1 vote

What's the difference between national calling frequency and national simplex calling frequency in the 2m and 70cm band plans published by ARRL?

Simplex implies transmission and reception on the same frequency without using a repeater. The band plan specifies that no repeaters are ever to transmit or receive on calling frequencies, nor should ...
Charles Bushong's user avatar
1 vote

What's the difference between national calling frequency and national simplex calling frequency in the 2m and 70cm band plans published by ARRL?

Correction. Simplex is a mode of communication regardless of frequency band or modulation being used. Simplex in Amateur Radio is one way communication at a time between two communicating stations. ...
user11520's user avatar

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