Diamond X50A - Again ...

[KQ4AQP]

I had a Diamond X50A installed on a 20-foot telescoping flag pole mounted atop my porch roof but was not happy with my ability to hit 2m, 70cm and GMRS repeaters some 20+ miles away in my hilly and forested terrain. Feed line is LMR-400 to the lightning arrestor and then LMR-400 directly to the 50-watt dual-band radio.

I took it down and replaced it with a small and lightweight GMRS ground plane antenna so that I could at least get into those local repeaters (21 miles and 36 miles). Access to GMRS repeaters and a local 70cm repeater is "fair", but still with too much crackling background noise for my satisfaction.

So now, I'd like to try the X50A again and perhaps add a 10' section to the height to see if that helps (trying to avoid guy lines on this metal roof). The issues are (1) too much static/cracking background noise, and (2) not getting to the 2m and 70cm repeaters at 20+ miles at all

Any suggestions?

 

[Ubbe]

If the map show low land as dark green and light/grey as high land then I wouldn't expect more range than what you already experience. I live 30ft above sea level and my antennas are another 30ft up and using 6dBi and 8dBi omni antennas I get 25 miles at the most. But being that low every feet you can get higher will improve your range.

Have you checked SWR that the antenna seems to work okay? You can easily take it apart and inspect so that it hasn't got any bad soldering of the bottom impedance match, or the capacitors between the different sections of elements.

/Ubbe

 

[Alliance01TX]

Howdy - just a few add on questions please...

How long is the coax cable run?
Is the Antenna in the clear or near obstructions or Metal building/roof?


Take the lightning suppressor OUT of the circuit and test SWR to the cable end with a dummy load at the connection point nearest the radio.

Then put dummy load to far-end of the LMR Coax and test into that point to "sectionalize- isolate any points of failure(s).

If you can test each LMR run separately that is the correct process to not add a barrel connector unless no other option.

Repeat with the lightning suppressor IN the circuit..

Based on my experience (HF and using dual band antennas like yours) I almost always find these issues:

1. Bad or marginal Coax connectors (especially the 'el-cheapo delux' Barrel Connectors and cheap 45 degree types)
2. Surge suppressor damaged by strikes / near misses - I have replaced several Alfa-Delta cartridges as when I took a look after SWR was not great, they have several "pits" on the cartridge indicating they took hits and thus degraded - still worked but SWR was impacted.
3. Water in my Coax connect(s) and a junction or at the Antenna base - will impact SWR and appear and disappear at times too.

As noted above SWR / Loss testing should confirm what might be impacting and could be a combo-issue, thus the reason to take it all apart to sectionalize the issue..

Hope you find the issue and correct.

Bill
KE5WGR

 

[KQ4AQP]

Howdy - just a few add on questions please...

How long is the coax cable run?
Is the Antenna in the clear or near obstructions or Metal building/roof?


Take the lightning suppressor OUT of the circuit and test SWR to the cable end with a dummy load at the connection point nearest the radio.

Then put dummy load to far-end of the LMR Coax and test into that point to "sectionalize- isolate any points of failure(s).

If you can test each LMR run separately that is the correct process to not add a barrel connector unless no other option.

Repeat with the lightning suppressor IN the circuit..

Based on my experience (HF and using dual band antennas like yours) I almost always find these issues:

1. Bad or marginal Coax connectors (especially the 'el-cheapo delux' Barrel Connectors and cheap 45 degree types)
2. Surge suppressor damaged by strikes / near misses - I have replaced several Alfa-Delta cartridges as when I took a look after SWR was not great, they have several "pits" on the cartridge indicating they took hits and thus degraded - still worked but SWR was impacted.
3. Water in my Coax connect(s) and a junction or at the Antenna base - will impact SWR and appear and disappear at times too.

As noted above SWR / Loss testing should confirm what might be impacting and could be a combo-issue, thus the reason to take it all apart to sectionalize the issue..

Hope you find the issue and correct.

Bill
KE5WGR

Thanks - I will certainly strive to follow your suggestions for compartmentalized testing ...

 

[KB0TJ]

For what it is worth... I bought three of these antennas until I realzied the X50A I was buying was actually tuned higher into the 2-way commercial frequencies!!
Opening up the sleeve over the loading coil allowed me to move the coupling a tiny bit on the shunt coil for better SWR on the ham bands.
Also, I found that connecting the tips of the "ground radials" with shorting wiresm all the way aroud,
also decreased the SWR even more.
Works well now and with the antenna at 25 feet high, I can hit all the repeaters solidly, anywhere from 40-75 miles away.