Conditions 07/11

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simbeav
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Conditions 07/11

Post by simbeav » 07 Nov 2018 09:19

Can anybody comment on TA conditions last night on MW ?

Strong regulars as well as rarities. Was doing some tests last night and they were VERY disappointing.

thanks Simon

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John Faulkner, Skegness
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Re: Conditions 07/11

Post by John Faulkner, Skegness » 07 Nov 2018 09:26

I'm probably not the person to help on this as my location can be extremely variable for transatlantic conditions.

Conditions are subdued here. I can hear regular east coasters, but not with any great strength. I have rock music on 1540 too close to KCKK's offset. I am sure this must be Radio Bahamas given the disturbed conditions. I haven't dug out an ID yet.

Things like 700 WLW is missing. This has been nightly until this latest disturbance. All I see now on 700, and on some other frequencies occasionally, are wide and smeary carriers, indicating auroral conditions. The solar wind app on Jaguar shows the disturbance is still affecting the band.

WJR is inaudible on 760. Three carriers are there, just reaching audio level occasionally.

It's a wash-out, but I think things are starting to recover.

tvdxrools
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Re: Conditions 07/11

Post by tvdxrools » 07 Nov 2018 09:28

utter garbage up here on both beverages David

simbeav
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Re: Conditions 07/11

Post by simbeav » 07 Nov 2018 09:55

OK. I'll come clean. I've "tried" putting up some sort of flag. Before going to bed, I was cautiously optimistic.

The usual Canadians were coming in 590,730, 930 680 etc. WFAN was in and out on 660. Cuba on 670.
710 Cuba was in all night quite strong sometimes mixing with WOR and CKVO.

But the higher in frequency that I wnt, the worse things became. 1010 was there most of the night , but declined alarmingly towards morning. Barely aany audio from KDKA. Nothing from Buenos Aires which is virtually always there on the loop. WFED barely audible, same with WWKB and even CHIN.

Just wondering if there is anything obvious that could cause drop of at higher frequencies.

Also some advice on use of the variable resistor. How do I optimise the setting.

thanks Simon

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John Faulkner, Skegness
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Re: Conditions 07/11

Post by John Faulkner, Skegness » 07 Nov 2018 10:06

The flag null is good for the whole of MW when the resistor value is optimised. Tune to something in the middle of the band, make sure it is to the rear of the flag heading, then adjust the resistor until you fully reduce or fully remove that signal. You're done!

If you have got the correct number of turns on the flag's transformer, then I can only assume it's the conditions which are messing things up. Give it another day or two to see. I usually find that the top half of the band is better, as it seems other DXers do, but the good conditions we had around the end of October / beginning of November, saw the whole band in good shape.

tvdxrools
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Re: Conditions 07/11

Post by tvdxrools » 07 Nov 2018 10:12

dont worry about conditions it was dire , as for resistor just pick a strong station off the bac,k of the antenna and null it as best you can , this is old video with a indoor slinky flag but gives u an idea , i had preamp on and had some stuff on in the shack which gave a bit of noise
https://www.youtube.com/watch?v=rgZ4y0Gql6k
ps what balun are u using , David

simbeav
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Re: Conditions 07/11

Post by simbeav » 07 Nov 2018 10:17

Thanks both - I'll have a play.

I sourced the balun from the Canadian ebay seller. I'm wondering if we got our wires crossed as looking back at the email trail it seems he has sent me 1:9. Would that be a problem ?

tvdxrools
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Re: Conditions 07/11

Post by tvdxrools » 07 Nov 2018 10:26

on flags i used 48/11 turn either ss or ol , David

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John Faulkner, Skegness
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Re: Conditions 07/11

Post by John Faulkner, Skegness » 07 Nov 2018 10:27

Sorry, I can't help with the values of baluns, etc. Way beyond the scope of my last remaining brain cell.

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John Faulkner, Skegness
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Re: Conditions 07/11

Post by John Faulkner, Skegness » 07 Nov 2018 10:29

If you are still having problems after a day or two Simon, I will send you a photo of the transformer in my box. For now, I wouldn't be surprised if it's the conditions which are at fault. Discrepancy noted by MW DXers between signals at the top and bottom of MW are real.

pe1etr
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Re: Conditions 07/11

Post by pe1etr » 07 Nov 2018 10:44

I tried Lazslo's Hungarian Kiwi SDR during the night (UTC) and there was almost zero TA, maybe a faint 1130 WWBR, nowt from WFED or WWKB.

Peter
Bangkok

tvdxrools
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Re: Conditions 07/11

Post by tvdxrools » 07 Nov 2018 11:14

Simon if i have any decent ferrite rings i will send you a balun to try if you want , David

simbeav
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Re: Conditions 07/11

Post by simbeav » 07 Nov 2018 11:33

Thanks Peter - Useful information.

Very kind of you David. I'll try a few more nights to see if things improve and if not then I may take you up on that.

Looking at the MediumWavelist logs for last night there isn't much apart from the Swedish superdxers and I have received everything that the Dutch dxers have reported (apart from WOND) and I usually have similar or slightly worse than them with the loop, so maybe conditions. Simon

satnipper
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Re: Conditions 07/11

Post by satnipper » 07 Nov 2018 18:16

Awful in the Cabardes badlands of southern Occitania - first night with 8x4m Flag up and kafa2500 Beverage balun. Though I have brought out a Flag balun from same seller with me.

Simon - do you have a beverage balun instead of Flag or Ewe? Didn't make any difference here in the summer - dx rolled in.

Stuart

simbeav
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Re: Conditions 07/11

Post by simbeav » 07 Nov 2018 22:11

It was sold as a flag balun, but I have to admit that I am a complete antenna ignoramus, I'm afraid.

satnipper
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Re: Conditions 07/11

Post by satnipper » 08 Nov 2018 11:35

So how do you know the impedance ratio? 9:1 would normally be for a long wire balun.

Conditions were awful again this morning here.

Stuart

daveB
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Re: Conditions 07/11

Post by daveB » 08 Nov 2018 11:43

From the published designs for MW flags a 16:1 balun is closer to the desired value. There is an image for a flag were the balun turns are 48/11 - which is a 19:1 ratio.

If the intention of the design is that the coax cable impedance is matched to the value of the terminating resistor then the 48/11 balun would match 50 ohm cable as a 910 ohm or 1 k resistor is specified. But if you are using 75 ohm coax then a 16:1 balun would match 1200 ohms. For a home wound balun a 48/13 ratio would be closer for 75 ohm coax (or 44:12).

This all theoretical number crunching - I wonder is anyone knows why the design settled on 48/11. Was it because a minimum number of turns (11) was needed for the low impedance side - and that set the number of turns for the primary? I can imagine the original was going to be 48/12 to give 16:1 ratio but taking one turn off the low impedance side gave a better match to the terminating resistor.

As posted previously - my garden doesn't lend itself to installing a flag antenna.

David
SDRPlay, AirSpyMini, RTL dongles, SB920s, Yamaha TX930. 5 ele compact yagi on rotator at 18ft agl. FM5 facing east, FM5 facing south, FM3 facing NE, OIRT dipole, 3-ele Moxon vertical facing east.

satnipper
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Re: Conditions 07/11

Post by satnipper » 08 Nov 2018 12:17

I think a turns ratio of around 16:1 is about right for a flag. I have made baluns with the small BN-73-202 binocular balun with a turns ratio of 12:3 which is 16:1 impedance ratio. Presumably 800 ohm is average for the far end termination resistance.

I've just checked kafa2500's description of his Flag kit. The balun is 18:1 impedance ratio and fixed resistor is 910 ohm. So all seems good.

The 9:1 transformer balun is included in the beverage kit along with a 450 ohm resistor.

Stuart

pe1etr
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Re: Conditions 07/11

Post by pe1etr » 08 Nov 2018 12:55

satnipper wrote:
08 Nov 2018 12:17
I think a turns ratio of around 16:1 is about right for a flag. I have made baluns with the small BN-73-202 binocular balun with a turns ratio of 12:3 which is 16:1 impedance ratio. Presumably 800 ohm is average for the far end termination resistance.

I've just checked kafa2500's description of his Flag kit. The balun is 18:1 impedance ratio and fixed resistor is 910 ohm. So all seems good.

The 9:1 transformer balun is included in the beverage kit along with a 450 ohm resistor.

Stuart
Just to help the puzzled newcomers,
The impedance ratio is obtain by squaring the number of turns and dividing by the lowest number
12X12=144
3X3 =9
144/9 =16
Hence 16:1

Peter

simbeav
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Re: Conditions 07/11

Post by simbeav » 08 Nov 2018 13:13

Basically I messed up. There were no flag antenna kits listed on ebay. I said I wanted the kit for a MW flag and he said to order the EWE with fixed resistor and he would adjust price after.

His final email said that he would be sending "1:9 matching transformer (50 to 450 Ohm) + variable termination resistor ( 500- 1400 OHM)" . In my ignorance I didn't question this

Completely my fault - I have no complaints.

So. What would be the effect of using the wrong Balun ?

Is it "just" a case of rewinding what I have ?

Last night was poorer than the night before - especially on higher frequencies.

I'm worried about the noise levels, again , especially on the higher frequencies.

Any suggestions ?

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