Lowering SWR on Comet Original CA-712EFC 460-470Mhz

[ChrisL]

Hi all,

 Got my antenna up and running after about 20 hours worth of work (not including Home Depot trips).

 First I want to mention the performance was better than I had hoped for. Very happy with that. Yesterday had a long chat on a repeater that I wasn't even expecting to hit.

 The second thing Is the the SWR was 1.5 on Medium power from my BTECH 50x1 and and 1.3 on low power. I would like to improve on this.

 I'm using 33ft. of  Times MicroLMR-400 coax with Amphenol PL-259 and Time Micro N-male connector. The #4awg ground rod wire is about 4ft long. The antenna is about 5 ft. over the top of the roof line. I'm using a Diamond 400 SWR meter.

 The instructions said to use either 1 or 2 loops for the rf choke. I made one loop. The radials have a VERY small adjustment of about 1/4" on all 3. I set the radials in as far as they would go and tightened things up. So I could extend them a bit.

 Would adding another loop to the rf choke help and would lengthening the 3 radial make a difference?

 Any advice would help.

 I forgot to mention that I tested the SWR on all the GMRS and GMRS repeater frequencies and they where all very close in measurement.

 Thanks guys for all your help.

 Chris

[WRTC928]

I.5 and 1.3 and you want to improve on it? Why? You could dink around for years, spend thousands of dollars, and get no improvement. In fact, there's a better than even chance you'd make it worse. "Good enough" is a valid concept.

[AdmiralCochrane]

On 1/16/2020 at 12:14 PM, ChrisL said:

Hi all,

 Got my antenna up and running after about 20 hours worth of work (not including Home Depot trips).

 First I want to mention the performance was better than I had hoped for. Very happy with that. Yesterday had a long chat on a repeater that I wasn't even expecting to hit.

 The second thing Is the the SWR was 1.5 on Medium power from my BTECH 50x1 and and 1.3 on low power. I would like to improve on this.

 I'm using 33ft. of  Times MicroLMR-400 coax with Amphenol PL-259 and Time Micro N-male connector. The #4awg ground rod wire is about 4ft long. The antenna is about 5 ft. over the top of the roof line. I'm using a Diamond 400 SWR meter.

 The instructions said to use either 1 or 2 loops for the rf choke. I made one loop. The radials have a VERY small adjustment of about 1/4" on all 3. I set the radials in as far as they would go and tightened things up. So I could extend them a bit.

 Would adding another loop to the rf choke help and would lengthening the 3 radial make a difference?

 Any advice would help.

 I forgot to mention that I tested the SWR on all the GMRS and GMRS repeater frequencies and they where all very close in measurement.

 Thanks guys for all your help.

 Chris

Refresh us on the antenna model.  You may be able to adjust the antenna itself, but none of those other ideas are likely to make the SWR better, you are already pretty good

[WRUE951]

13 hours ago, AdmiralCochrane said:

Refresh us on the antenna model.  You may be able to adjust the antenna itself, but none of those other ideas are likely to make the SWR better, you are already pretty good

1:5 is pretty good..  Don't mess with it.  

[WRYZ926]

I definitely would not mess with the antenna if the SWR is 1.3 and 1.5. I have a Comet CA-712EFC and the SWR is 1.7 and I will not bother trying to mess with it as long as it is under 2:1

[SteveShannon]

On 1/16/2020 at 10:14 AM, ChrisL said:

The instructions said to use either 1 or 2 loops for the rf choke. I made one loop. The radials have a VERY small adjustment of about 1/4" on all 3. I set the radials in as far as they would go and tightened things up. So I could extend them a bit.

 Would adding another loop to the rf choke help and would lengthening the 3 radial make a difference?

 

Try them and see if the performance of the antenna improves. Performance is measured in signal reports and range, not SWR.

But there’s practically nothing to be gained with a lower SWR than what you have.

[LeoG]

47 minutes ago, WRYZ926 said:

I definitely would not mess with the antenna if the SWR is 1.3 and 1.5. I have a Comet CA-712EFC and the SWR is 1.7 and I will not bother trying to mess with it as long as it is under 2:1

My Comet is 1.01:1 with 47 watt pushing out the back end of the KG1000G.  And during rain or snow I've only seen it go as high as 1.05:1.  And it's not like it's only on once channel, it's across quite a bit of them.  I double checked with another meter because I couldn't believe it, same results.  And yet my Retevis antenna is at 1.7:1, so I know it'll read something else and not just fake fantastic results.

[AdmiralCochrane]

I still would not trust those numbers ... unless I was using very low power and lossy coax

[LeoG]

Messi & Peloni cable connected to a lightning arrestor and then 1/2" Andrews Heliax to the Comet CA-712EFC.  When I had my Retevis antenna up I had another length of M&P after the lightning arrestor and had issues and the SWR moved around quite a bit with the temperature going above and below freezing.