Icom AH8000 vs Comet DS150S

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hermite

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I just purchased the AH8000 Discone for my Icom R-8500 Receiver.

I removed my Comet DS150S Discone and installed the AH-8000 in its place. (60’ mast above ground).

Went from a good +40dB (ds150s) to a an extremely poor 4dB (ah8000) on all local stations.

And yes I used the supplied 5D-2V cable. I also tried it with my RG/8-U coax.... same difference.

What is this all about ???
 

Rt169Radio

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Maybe something is overpowering your new antenna that your older antenna could handle?
 

hermite

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Hi. I know nothing about HAM Radios. I just scanner for the pleasure... so, when you mean something is overpowering the antenna, what does that really mean. What should I be looking for exactly? I sent my complaint to Icom Support... see what happens. This antenna will not likely be a keeper... and for the price... I was expecting it to be `very` compliant with my Icom R-8500.
 

SCPD

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Time to put the comet back on your coax ? or maybe get a Diamond D130JN discone which I can assure you is a great discone. (also has claimed wider coverage than the Icom AH-8000) Be sure to get the model with the N connector if you do get the Diamond.

Diamond® Antenna ~ D130J Super Discone Antenna

I tend to find that checking places like Eham reviews before making a major purchase a good idea. Cause if a product is a dud .. people will usually report it there, but I see no reviews on the AH-8000 just the AH-7000.

eHam.net Reviews

Interestingly .... someone on Eham is claiming that the Icom AH-7000 is the same antenna as the Diamond. I cannot confirm this ... but I know that I had very good results with my Diamond D130JN.
 
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prcguy

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I have not used an AH-8000 yet but judging from the construction there should be very little difference between your Comet DS150s and the AH-8000 over the 100 to 500MHz range. I doubt if you would even notice a difference.

The Comet has a vertical whip that will enhance VHF lo band a little (its sharply tuned to 6m) so that would explain any difference there and I suspect the Icom would work a bit better on 800MHz.

So if your drop in reception is in the 100 to 800MHz range and you used the exact same feedline I suspect the AH-8000 is not assembled correctly or its defective, although there is not much to go wrong with one. Or you have a problem with one of the feedline connectors.
prcguy
 

Nap

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so, when you mean something is overpowering the antenna, what does that really mean.
It's about powerful local stations that, combined with a high gain antenna, will bring the RF amplifier in your receiver to saturation and produce high noise floor, poor S/N and distortions on all frequencies. This is fixed either by introducing an attenuator to bring down the signal into the linear zone of the RF amplifier, or adjusting the RF amp gain, or inserting selective/highpass/lowpass filters between the antenna and the receiver to attenuate just the powerful stations.

However from your description this doesn't seem to be the case, I would suspect an error in assembling the antenna or a problem with the connectors/cable.
 

hermite

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Tks for the replies. Indeed the drop is in the 100-800 range (I don't listen pass that range). The local weather station antenna is 5 miles from my house on the moutain top and I have clear line of sight. (162.55MHz).
I'm pretty confident that nothing is assembled wrong, cables and connectors are good.
Also, there isn't much that could be 'physicaly wrong' with the antenna.
A side by side comparaison is all I have. Does anyone else have hard/concrete evidence of such a comparaison AH8000 to a DS150S?
The quality of the antenna sucks. I managed to damage 1 set nut with the Allen wrench, and, 2 screws on the mounting pipe...! It is not 'solid' if you know what I mean. Still no news from IcomAmerica tech support...
The Comet is back on my Coax, works great as always did. Why the change you ask? To get even better reception... but not the case it seems.
 

hermite

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The AH-8000 is a 3dB gain antenna. I found this peace of info on the Web...
The number of dB is 10 times the logarithm of output power divided by input power. As an example, an input power of 30 milliwatts and output power of 60 milliwatts equates to 3 dB of gain. A convenient fact to remember is that 3 dB of gain means the doubling of power. For instance, a transmitter outputting 100 milliwatts to an antenna having 3 dB gain produces 200 milliwatts effective power.
Could this be my problem?
 
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