Karl's RF projects page

Antennas & Line

a 3-element yagi beam antenna for 1 1/4 meters or 70 ceni-meters K-built, light Duty

a 3-element yagi beam antenna for 1 1/4 meters or 70 ceni-meters K-built, heavy Duty

A simple dipole K-built, for 1 1/4 meter band; medium duty

A simple dipole K-built, for 1 1/4 meter band; heavy duty

K-built, a dual band unity gain antenna set For 1 1/4 and 2 meter band; medium duty

Repair an antenna Collinear (Station Master) type

Build a new antenna Collinear type

Evaluation of Arrow's 1 1/4 meter yagi antenna 220-S5, light duty

Evaluation of Tram's VHF antenna 1487, base, light duty

Evaluation of Tram's dual band antenna 1181, mobile, light duty

Evaluation of Tram's CB antenna mobile, light duty

Evaluation of Comet's dual band antenna B10, mobile, light duty

Evaluation of Comet's dual band antenna 460S, mobile, light duty

Evaluation of Laird's 70-cm antenna FG 4405, base, medium duty

Evaluation of TeleWave's 70-cm antenna ANT450F2, base, heavy duty

Evaluation of TeleWave's 70-cm antenna ANT450F10, base, heavy duty

Evaluation of Sinclair's 70-cm antenna SC320-SF4SNM, heavy duty

Evaluation of Diamond's dual band antenna NR-72BNMO, mobile, light duty

Evaluation of Diamond's antenna X50N, base, medium duty

Evaluation of Crushcraft's antenna CRX-150, base, light duty

Evaluation of HYS-701N HT antenna (whip)

A look at corner reflector antennas

A look at RF paths Where these antennas could help

A look at commercially made antennas Just to buy

Hard line splicing Cheap solution

Connector discussion For RF

Crimp connectors

Clamp connectors

Cavity and duplexer notes

Cavity Band change from 2 to 1.25 meters

Grounding discussion using the R-56 as a standard

Path Engineering Calculate (FM)Fade Margin

Receiver desense Testing system performance

RF and RFI management Practices and notes for remote sites

External RF amplifier For the IFR 500 and 1200 service monitor

The commercial rated antennas are best for harsh weather conditions, especially for winter. While the fiberglass radome type is the best for that the open loop types are good too so should be considered for your installation. However, you need to be care that type will work well in the amateur band. For example, here shows an excellent return loss figure for the VHF-Hi Band section, but just barely clears the accepted "standard" in the amateur band. This sweep/plot shows that some of the open loop types are not broad banded as previously thought. It's best to do you homework before ordering such an expensive antenna.

 

 

When installing line and antenna it's important to properly seal the connections. Normally, mastic pad is used followed by a good quality electrical tape. The Author sometimes what's available which would be "700", Scotch "33" or "88". The latter is the first choice because it works well enough in cold weather. Some times at the MCP/home the Author will use only a single layer of tape as an experiment. Shown here is two adaptors removed from service after being on the tower for a decade-all appears to still be clean.

 

 

Here's some example of sealing materials you can purchase:

 

[SRG home Direction]