Thanks for the compliment but just an AMATEUR radio operator myself, I don't know everything, always learning something new.
Anyway, let us know what you come up with on these filters.
Re: MW Images In LW Band
- Thread starter ridgescan
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Thanks for the compliment but just an AMATEUR radio operator myself, I don't know everything, always learning something new.
Anyway, let us know what you come up with on these filters.
ridgescan
Member
Yeah well that's me, full of.....compliments
I shot an order for both filters so I'll be getting them in a few days. Will let you know.
ridgescan
Member
Well, 12 days later I finally got the filters. There are no instructions. I asked Dale this but no reply yet. Does it matter on a filter like these which side the feedline goes in to? There are no indicators on the filters.Yeah well that's me, full of.....compliments
I shot an order for both filters so I'll be getting them in a few days. Will let you know.
An L type filter needs to develop the output voltage across a component so therefore it would make a difference which port is input and which is output. However, with a T or pi configuration filter it probably does not matter. Given that your filter is a passive device likely a T or pi (maybe even multi-stage) and neither port on your filter is labelled my guess is it probably doesn't matter.
However, again, that is just my guess.
ridgescan
Member
Yeah well that's a good guess cause Dale just told me they're "bilateral". Thanks buddyAn L type filter needs to develop the output voltage across a component so therefore it would make a difference which port is input and which is output. However, with a T or pi configuration filter it probably does not matter. Given that your filter is a passive device likely a T or pi (maybe even multi-stage) and neither port on your filter is labelled my guess is it probably doesn't matter.
However, again, that is just my guess.
ridgescan
Member
Well I put the PAR BCST-LPF low pass filter on the R75 to the 100' endfed wire and it completely eliminated ALL images in LW. Definitely works and works well!
Good news.
Do you notice any loss? In other words, if you tune in a weak signal and then switch in the filter is the signal attenuated at all ?
ridgescan
Member
Yeah I checked for that and am happy to report zero loss or difference in desired signals
and the cool thing also, is I can actually use my preamp in the R75 in LW and still no images. Before, I could never use preamp. So this means I may be able to dig up more far stuff.pjxii
Member
I have an AM broadcast station on 550 kHz kicking out 500 kW (that's not a typo) from Cuba across the Gulf from me that might cause me problems using a wire antenna. How well does the Par LPF do on the lower portion of the MW band?
ridgescan
Member
Get one. Mine is extremely effective with 560 KSFO and 610 KEAR both which are right near me.
pjxii
Member
That's what I was hoping to hear, thanks!
ka3jjz
Wiki Admin Emeritus
If you're technically inclined, you should always check the response curves to see if the filter will actually do what you want. In the case of the PAR filters, click the image of the filter.
Mike
Mike
pjxii
Member
Actually, I did that and the chart looked to be around -25 to -30dB at 550 kHz, but a manufacturer's chart and a real user's experience may be very different.
Ironically, I bought an Apex Radio HPF2050 because there is a 10kW/daytime AM broadcast transmitter on 1660 kHz about 2-3 miles south of my eventual homesite. Their chart looks better for my HF needs than other high pass filters designed for the 160 meter amateur band but until I get a chance to actually use it I really just don't know what the actual useful frequency cutoff is
Don't have a local 500 KW station around here for comparison but there are a couple of local 500 watt daytimers on 560 and 580. Switching in the PAR LPF pulls their S9+10-20 db signals down into the noise level.
If you are using a wire antenna, use a 9:1 transformer between it and the filter.
btw... can't find any station listed on 550 running that amount of power... what station are you referring ?
pjxii
Member
CMBV in Wajay, Cuba is the big flamethrower on 550 but Radio Enciclopedia on 530, while only listed at 10kW is very strong here as well (sure seems like much, much more than 10kW unless they're using a highly directional beam towards Florida).
pjxii
Member
Great thought! I completely forgot about all the accessories packed away in my bedroom closet that I haven't had a chance to use here. There's an MFJ-955 in there as well as a Dymek Mackay preselector. I do think though that it'd probably be a good idea to get the LPF though. Can't have enough radio gear...
ka3jjz
Wiki Admin Emeritus
You have one of those DP40s??? If you put that sucker in, I highly doubt you will need anything else...if this is the one PJXII has, here's a pic...these things are VERY VERY valuable...
https://www.universal-radio.com/catalog/preamps/DP40.html
Passive units like this are very useful for these wide banded SDRs with little or no front end filtering, as well as some real old single conversion radios. There are a couple still being made - Cross Country in the UK and MFJ has them.
Mike
https://www.universal-radio.com/catalog/preamps/DP40.html
Passive units like this are very useful for these wide banded SDRs with little or no front end filtering, as well as some real old single conversion radios. There are a couple still being made - Cross Country in the UK and MFJ has them.
Mike
pjxii
Member
Yes, that's the one. I bought it years ago figuring it may come in handy but have yet to use it. Came with a chart of the frequency ranges and the passband widths plus attenuation figures. I figure it will help the DX-1000 immensely.
The MFJ-955 is a rare bird as well, unlike the 956 it will (supposedly) tune in the VLF ranges from 10 kHz on up.
ka3jjz
Wiki Admin Emeritus
Yes it should work just fine with that DX1000. If I remember rightly these units were built to work in a high RF density environment, so it does sound like it's right up your alley. If you have more than 1 HF receiver or a SDR like the Funcube, use the MFJ on the other one. You could even rig some patches so you can switch between the two - just don't go too overboard with the patches, as they could end up potentially being unwanted antennas.
That DP40 would fetch a heckuva price on fleaBay, for sure...Mike
That DP40 would fetch a heckuva price on fleaBay, for sure...Mike
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