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Author Topic: Diagnosing deaf 2m receive on TS-2000  (Read 6650 times)
N6DZR
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« on: August 29, 2012, 12:22:21 PM »

I need help with the 2m receiver on my kenwood ts-2000. The received signal seems too low... for example, during the last VHF contest I was trying to work a station who said he could hear me fine, but I could not make him out among the noise.

The VHF antenna is mounted on the same mast as my HF/6m yagi, just a little higher up. I'm wondering if the 6m transmissions I was making perhaps damaged something in the 2m receiver of the TS-2000. Other than swapping out for another radio I'm not sure how I would determine that.

If the VHF antenna is in fact too close to the HF antenna, I'm wondering if using a triplexer would help. Right now I use a diplexer to feed the VHF and UHF connectors on the radio from one feed line. I was thinking a triplexer would help reduce the HF signal strength being fed into the VHF connector.

-Jeff
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K6AER
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« Reply #1 on: August 29, 2012, 02:46:10 PM »

your TS-2000 already has a front end filter to remove anything but VHF signals.

Why do you think the Receiver is numb. Was the station you talk to running an amplifier? There can be as much as a 20 dB difference between stations due to power.

Have you compared it with other rigs?

Does someone have a calibrated source to check it with?

Normally the radio is used with the 2 meter preamp on.
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N6DZR
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« Reply #2 on: August 30, 2012, 08:09:54 AM »

your TS-2000 already has a front end filter to remove anything but VHF signals.

Why do you think the Receiver is numb. Was the station you talk to running an amplifier? There can be as much as a 20 dB difference between stations due to power.

Have you compared it with other rigs?

Does someone have a calibrated source to check it with?

Normally the radio is used with the 2 meter preamp on.

Thanks for the reply. If the other station was >100w then my situation is worse - he could hear me fine (with my 100w), but I could not hear him. I suppose it could have been the opposite... he could have been running 5w.

The only other 2m radio I have is FM. It would be difficult to compare using that without switching antennas around a lot. The FM radio is using a vertical and the ts-2000 a horizontal log periodic.

Yes, I had the pre-amp on.

I think I will have to find someone local with another ts-2000, then find someone a decent distance away who can transmit to us a few times on each radio.

I know the ts-2000's S-meter tends to read low, but I was comparing using my ears.

Thanks for the comments.. I'll keep thinking and asking around.

-Jeff
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W5DQ
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« Reply #3 on: August 30, 2012, 09:55:58 AM »

I need help with the 2m receiver on my kenwood ts-2000. The received signal seems too low... for example, during the last VHF contest I was trying to work a station who said he could hear me fine, but I could not make him out among the noise.

The VHF antenna is mounted on the same mast as my HF/6m yagi, just a little higher up. I'm wondering if the 6m transmissions I was making perhaps damaged something in the 2m receiver of the TS-2000. Other than swapping out for another radio I'm not sure how I would determine that.

If the VHF antenna is in fact too close to the HF antenna, I'm wondering if using a triplexer would help. Right now I use a diplexer to feed the VHF and UHF connectors on the radio from one feed line. I was thinking a triplexer would help reduce the HF signal strength being fed into the VHF connector.

-Jeff


On VHF, there are many variables to consider. First and foremost is antenna polarization vs propagation mode. You did not mention what kind of antenna you were using nor the distance to the other station. You did mention you were usng 100W which in and of itself eludes to the fact that you 'COULD' have a good signal to the antenna PROVIDING that you have quality feedline to the antenna and the antenna is of proper polarization and gain to support the needed signal for the QSO - which apparently it did for the other end to hear your signal FINE.

If the other end had say a long boom yagi of several wavelengths (5 or more wavelengths or better yet, stacked long boom yagis), then they most likely could hear you well enough to QSO (his reported hearing your FINE is a relative reference as I can hear someone fine and their signal not be very strong at all (well below a 59 report). Also if you have only a small yagi of 5 or so elements on 2M, you may not be able to pull the other signal up much above the noise at all but yet still generate enough ERP to allow the better equipped station to pull you out and understand your speech well enough.

I am assuming that since this was a contest, that the distance was not local ground wave signal but rather terrestrial or some other 2M weak signal propagation mode. Also you probably are aware but if not, cross polarization on VHF signals will cost you up to 20dB on your link budget so if you are using a vertical on top of your HF stack, that could be most of your problem. What coax type are you running to the 2M antenna?

I use a TS2000/X on 6M and up and have no issues. I even run up to 1200 watts on 6M with the 2M antenna in the near field (although not the same tower) and suffer no ill effects.

I am betting the TS2000 is just fine but a second rig would definitely allow confirmation.

Gene W5DQ
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Gene W5DQ
Ridgecrest, CA - DM15dp
www.radioroom.org
W5DQ
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« Reply #4 on: August 30, 2012, 10:01:04 AM »

Quote
and the ts-2000 a horizontal log periodic.


What are the specs on this antenna? How much higher is this above the 6M?

Gene

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Gene W5DQ
Ridgecrest, CA - DM15dp
www.radioroom.org
KA4POL
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« Reply #5 on: August 30, 2012, 10:36:01 AM »

A logperiodic is not an ideal antenna for critical situations. A filter for 2m got to be very good to keep the third harmonic from 6m out. To really check this you need an HF generator to feed a defined signal into the rig.
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N4KZ
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« Reply #6 on: August 30, 2012, 11:55:45 AM »

As a former TS-2000 owner, I can say it's a nice rig that does a lot on many bands and modes. But its 2 meter sensitivity is a bit lacking - whether it's on FM or SSB. I always used an external preamp with mine when operating on 2 meter SSB and CW. There are mods on the Internet from people smarter than me who have figured out ways to increase its 2 meter sensitivity. But there could be other factors at play too. You didn't mention the mode used for these contacts and specifics on your antenna type and polarization - all of which could be factors in the feeling that you were heard better than you were receiving. Rather than modify my TS-2000, I chose to use an outboard preamp which I already had on hand. It worked fine. Just food for thought.

73, N4KZ
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KQ6Q
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« Reply #7 on: August 30, 2012, 08:41:18 PM »

one point not mentioned  -Log Periodics are directional. What direction was your LP pointing, and what direction is the other station in ?
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N6DZR
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« Reply #8 on: August 30, 2012, 09:15:02 PM »

Wow - lots of good questions. I'll try to answer all of them.

My antenna is the Elk 2m/70cm log periodic. I know that's not a lot of antenna, but it enabled me to get a horizontal signal with some gain. The web site says it is 5 elements and provides 8.7 dBi.

The 6m antenna is different and I was using a different radio for 6m as well.

The Elk antenna is fed with 75 feet of LMR-600. There is a diplexer on the radio end that feeds the 2m UHF connector and the 70cm N connector.

The antenna is 4 or 5 feet above a 3-element steppir. This close distance is one of my concerns. However, when I transmit on 6m from my other radio I do not see or hear anything on the ts-2000. Likewise when I transmit full power on 2m or 70cm I do not see/hear anything on 6m. I did not notice any SWR changes to the steppir when the elk was added. So I'm thinking/hoping there is little interaction.

The antennas are about 30-35 feet off the ground and we live at about 3200 feet with a clear shot to the south, which is where the other station was when could not hear him. Other than the trees it was line-of-sight. The antenna was pointed in his general direction. I could hear him fine on 6m, but again I don't know what power he was using.

The mode used during the contest was SSB. I believe it was ground wave as the farthest I got with 2m was 1 or 2 grid squares away.

A buddy who lives about 4 miles from me gave an idea. There is a beacon about 137 km away from me (CM99ew -> CM88ws) that I receive S-5 on the horizontal antenna. My buddy gets it S-4 on his vertical also using a ts-2000. He lives closer to the beacon. So this simple test seems to suggest that my receiver is OK and the experience during the contest most likely was some other factor(s).

Next time I can't hear someone, I'll ask them what power and antenna they are using.

-Jeff
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KA4POL
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Posts: 2028




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« Reply #9 on: August 30, 2012, 10:22:22 PM »

Beacons are a good source for measuring conditions as well as checking receivers by comparison. Vertical and horizontal polarization are not to be taken to strictly. There is always a possibility of rotation by reflections, particularly in mountainous regions. Usually for SSB you use horizontal antennas. Check out what that beacon uses as antenna and what power it produces. 137km is a secure distance, you should always be able to receive it.
A last thing to mention. The ARRL test back in 2001 resulted in preamp on .48┬ÁV at 10dB (S+N)/N on 2m. This is not a very good value.
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G8JNJ
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« Reply #10 on: August 31, 2012, 01:27:29 AM »

Hi,

Just be aware that contest grade stations on the VHF /UHF bands usually have very good receive systems. Most probably with a low noise masthead mounted preamplifier, to maximise capture of weak signals.

You have 75ft of LMR600, which is a good cable but will still introduce just under 1dB of loss. Plus a Diplexer at the transceiver end of the cable which will probably introduce another 0.5 to 1.0dB of loss. The combination of these two losses will degrade your TS-2000 RX noise figure (which is not that good to start with) by something in the region of 2.0dB. So your overall receive system noise figure could well be around say 8dB to 10dB. And this doesn't include any contribution from Urban noise picked up by your antenna.

By contrast a good contest grade station may have a RX system noise figure of 0.8dB. Which means he can hear you if you are running 100W. But he would need to be running 1KW or so for you to be able to hear him.

Regards,

Martin - G8JNJ

www.g8jnj.webs.com

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W5DQ
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« Reply #11 on: August 31, 2012, 06:08:00 AM »

I routinely hear a station appx 90-100 miles south of me on 2M and he's running 600+ watts in the contests yet he's barely discernible above the noise. I only have 11 elements on 2M at 30 feet but I hear other stations much louder and farther away, so I know it is just our pathway. My opinion is the QSO from the original post was just one of those that just either wasn't the greatest path or not the best condx or both. If it becomes a pattern then I would look for a solution but now from the sound of it, you're looking for a fix to a non-problem.

I would, however, investigate getting a better 2M antenna as soon as possible if your serious about 2M contesting. Your 'Yugo' wasn't designed for 'drag racing'  Grin

Good Luck & 73

Gene W5DQ
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Gene W5DQ
Ridgecrest, CA - DM15dp
www.radioroom.org
N6DZR
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Posts: 100




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« Reply #12 on: August 31, 2012, 09:16:53 AM »

I would, however, investigate getting a better 2M antenna as soon as possible if your serious about 2M contesting. Your 'Yugo' wasn't designed for 'drag racing'  Grin

R R R - I completely agree. The antenna choice was purely an inexpensive way to get on 2 more bands. Before this I was using a dual band vertical.

I appreciate all of the questions, comments, and suggestions.

-Jeff
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