AOR DV1 music on the AM air band

[kamilkamien]

Hello, the HPN-30118 is made here in Czech republic, you can buy it at DD-amtek for example. I have many such filters in my shack, all work as designed.

e-Shop DD AmtekDDAMTEK HPN-30118

Dodavatel radiových a anténních systémů a jejich příslušenství, Měřicích přístrojů Autorizované zastoupení Kenwood, Yaesu, Ten-Tec, RigExpert, WiMo, Xiegu, SSB Electronic, Innovantennas, Optibeam aj.

eshop.ddamtek.cz

Try to contact them if they ship to Poland, I think this is much easier than bring it from US. The price is cca 23 USD when converted from CZK to USD.
They also sell HPN-30118-T with a parallel choke at the input side, that conducts static electricity from Discone type antennas.
They have plenty of other filters, preamps, attenuators, splitters, etc... for various bands:

e-Shop DD AmtekPředzes., filtry, preselektory, attenuátory

Dodavatel radiových a anténních systémů a jejich příslušenství, Měřicích přístrojů Autorizované zastoupení Kenwood, Yaesu, Ten-Tec, RigExpert, WiMo, Xiegu, SSB Electronic, Innovantennas, Optibeam aj.

eshop.ddamtek.cz

Oh yes!
This is probably what I'm looking for. I wrote a message to the seller. He has the entire range in his store! I almost ordered from the USA and now I have a faster alternative from a neighboring country. Thank you for your help!!!!!!

 

[rumcajs_tr]

Oh yes!
This is probably what I'm looking for. I wrote a message to the seller. He has the entire range in his store! I almost ordered from the USA and now I have a faster alternative from a neighboring country. Thank you for your help!!!!!!

If you fail to get the seller to send it to Poland, just let me know via private message here on RR. I can probably buy for you what you need and send it to your address, if all other ways fail.

 

[kamilkamien]

If you fail to get the seller to send it to Poland, just let me know via private message here on RR. I can probably buy for you what you need and send it to your address, if all other ways fail.

Only now I saw that you are my neighbor Great! Thank you for your help! The store's website states that they ship to Europe, so I don't think there will be a problem. Again thank you very much!

 

[ka3jjz]

Here's a thread that would be very useful for some more background info on filters

FM bandstop filter comparison

I rolled some numbers on the RTL-SDR FM bandstop filter and the HPN-30118 AM/FM filter using a VNA. The results are interesting compared to the ZBSF-95+, especially when you hit VHF Air voice at 118 - 137 MHz. The ZBSF-95+ numbers come from their spec PDF as I do not own that yet. There are...

forums.radioreference.com

Mike

 

[G7RUX]

I would first make sure that you can rule out a fault with the DV1. I myself also have a DV1 and operate it with a Diamond X-50. The local VHF radio station is about 3.5 KM (as the crow flies) away, but I have no spillover from the radio range in the aircraft radio band. Do you have the possibility to test another station receiver on your antenna?

The problem with intermodulation is that how it manifests depends heavily on the frequency relationships. They tend, with wideband receivers, to lead to a raising of the noise floor in certain frequency ranges if they don’t give rise to identifiable carriers. Consequently the same receiver will behave very differently in what appear to be very similar situations.

 

[rumcajs_tr]

One more comment - please try to identify the source of the radio broadcast to choose the proper filter. There is a great difference if the broadcast comes from shortwave AM radio station or whether it comes from CCIR FM radio band:

• AM longwave / shortwave radio band varies from 0 to 30MHz, the modulation is usually AM and if the transmitter is close, it can heavily impact all your reception. However, nowadays, the LW/SW radio stations are becoming obsolete in Europe and are turned off one after another. It usually have huge antennas (towers) and you can find on the web the location of such transmitters. The power can be hundreds of MW in power.
• FM CCIR radio broadcast is located in the low VHF band in the area of 88-108MHz. The modulation is WFM (wide FM). This band is very close to the AIR band and the CCIR FM broadcast is usually responsible for the so called "bleeding" of radio broadcast into AIR band even though the transmission is in WFM and the AIR is in AM.

If you suffer from the first case (SW radio broadcast), you have to buy HPN-30118, which is a combination of 30MHz high pass filter and 80-118 notch filter, so it blocks everything below 30MHz and also blocks everything in the 80-118 MHz range. However, because of this, you loose the HF reception below 30 MHz on the receiver (HF bands, CB band, ...), so it is only recommended if you have a separate HF antenna and a combiner to use them both on the same antenna port.

If your problem is coming from the FM CCIR radio broadcast (stations between 88-108MHz), you should consider NF-88118 instead of HPN-30118. NF-88118 is a notch filter, which filters just the FM broadcast band, but pass through everything under 88MHz and above 118 MHz, so you will keep the reception below 30 MHz on your discone.

e-Shop DD AmtekDDAMTEK NF-88118

Dodavatel radiových a anténních systémů a jejich příslušenství, Měřicích přístrojů Autorizované zastoupení Kenwood, Yaesu, Ten-Tec, RigExpert, WiMo, Xiegu, SSB Electronic, Innovantennas, Optibeam aj.

eshop.ddamtek.cz

The easiest way to detect what is the source of the music signal is to grab a FM radio and try to find the same music, which plays on the scanner, after that you will be sure that this is some local FM station. My guess is this is the case.

 

[kamilkamien]

One more comment - please try to identify the source of the radio broadcast to choose the proper filter. There is a great difference if the broadcast comes from shortwave AM radio station or whether it comes from CCIR FM radio band:

• AM longwave / shortwave radio band varies from 0 to 30MHz, the modulation is usually AM and if the transmitter is close, it can heavily impact all your reception. However, nowadays, the LW/SW radio stations are becoming obsolete in Europe and are turned off one after another. It usually have huge antennas (towers) and you can find on the web the location of such transmitters. The power can be hundreds of MW in power.
• FM CCIR radio broadcast is located in the low VHF band in the area of 88-108MHz. The modulation is WFM (wide FM). This band is very close to the AIR band and the CCIR FM broadcast is usually responsible for the so called "bleeding" of radio broadcast into AIR band even though the transmission is in WFM and the AIR is in AM.

If you suffer from the first case (SW radio broadcast), you have to buy HPN-30118, which is a combination of 30MHz high pass filter and 80-118 notch filter, so it blocks everything below 30MHz and also blocks everything in the 80-118 MHz range. However, because of this, you loose the HF reception below 30 MHz on the receiver (HF bands, CB band, ...), so it is only recommended if you have a separate HF antenna and a combiner to use them both on the same antenna port.

If your problem is coming from the FM CCIR radio broadcast (stations between 88-108MHz), you should consider NF-88118 instead of HPN-30118. NF-88118 is a notch filter, which filters just the FM broadcast band, but pass through everything under 88MHz and above 118 MHz, so you will keep the reception below 30 MHz on your discone.

e-Shop DD AmtekDDAMTEK NF-88118

Dodavatel radiových a anténních systémů a jejich příslušenství, Měřicích přístrojů Autorizované zastoupení Kenwood, Yaesu, Ten-Tec, RigExpert, WiMo, Xiegu, SSB Electronic, Innovantennas, Optibeam aj.

eshop.ddamtek.cz

The easiest way to detect what is the source of the music signal is to grab a FM radio and try to find the same music, which plays on the scanner, after that you will be sure that this is some local FM station. My guess is this is the case.

All this information is very useful. Where I live, there are a mix of radio stations from Poland and Germany that operate on similar FM bands. What I recorded was clearly music from commercial radio. Unfortunately, at the moment I have no way to check what music it is from which station. On the Polish side, the nearest FM transmitter of commercial stations is 50 km away and it easily covers my town.
I'm wondering whether to buy the NF-88118 or HPN-30118 filter
I don't listen to HF now, but that may change in time. The question is how one behaves towards the other. I talked to a filter seller from Poland and he said that a filter that operates on a narrow band, e.g. 108-136 mHz, will be more effective than one that operates at 108-250 mHz. He said that the smaller the range to be covered by the filtration, the more effective it is. I do not know. I'm waiting for a response from the store in the Czech Republic

 

[G7RUX]

As a related note, I have a Yaesu VR-5000 (bought cheap at a rally) that I use for airband monitoring most of the time and this receiver suffers terribly from intermods. In my case this is caused by FM broadcast radio in Band II and manifests mostly as a hugely raised noise floor across the whole of VHF air band but especially in the lower half. Installing a NooElec Distill:FM bandstop filter just before the receiver input almost completely resolves the issue. I'm sure better filters are available (in fact I know they are as I have a few) but these are eaily available, cheap and extremely effective.

 

[Ubbe]

If you don't need to receive the 70MHz-80MHz band then the ZBSF-95+ are the best one when it comes to a huge broadcast attenuation and still pass 118MHz. The DV1 has a internal bandpass filter for 100MHz-180MHz so are very wide and includes the FM broadcast frequency range so will always need a broadcast bandstop filter to be used for VHF reception.

I have the HPN30118 as I need to receive 85MHz and used a VNA to sweep it and had to adjust the coils inside it to tune it more exact, but it is pretty good as it is from the factory and also attenuate shortwave if that are needed. At one time the soldering broke between the components and the BNC connector so keep an eye out for that.

The AOR DV1 receiver do not perform to what its price tag would indicate. There are lots of users who complain that it so easily overloads. It has a lot of features and functions but the receiver in it are terrible.

/Ubbe

 

[G7RUX]

The AOR DV1 receiver do not perform to what its price tag would indicate. There are lots of users who complain that it so easily overloads. It has a lot of features and functions but the receiver in it are terrible.

/Ubbe

To be honest I suspect this is reasonably true for many non-pro wideband scanner receivers and quite a few of them seen to benefit from the addition of some appropriate filtering for the intended purpose. My personal experience is that decent filters usually make quite a decent difference in overall performance.

 

[G7RUX]

After having used the Flamingo filter (in “barebones” form) with my VR5000 for a little while I got hold of the Flamingo+ which gives 70 dB attenuation in the middle of the stop compared to 30 dB or so, with a bit more loss at the low end of airband. The performance of this filter is really rather good and the noise floor in airband is down around where I would normally expect it to be.

The Nooelec gear is very good value and does a decent job without having to spend big money on the commercial kit.

 

[bagmouse7]

After having used the Flamingo filter (in “barebones” form) with my VR5000 for a little while I got hold of the Flamingo+ which gives 70 dB attenuation in the middle of the stop compared to 30 dB or so, with a bit more loss at the low end of airband. The performance of this filter is really rather good and the noise floor in airband is down around where I would normally expect it to be.

The Nooelec gear is very good value and does a decent job without having to spend big money on the commercial kit.

One of the biggest benefits to using these FM filters for Airband is that they lower the noise floor across the band. This usually will let you lower the squelch which leads to more hits and better scanning across the band.
This is especially useful for sensitive receivers.

 

[G7RUX]

One of the biggest benefits to using these FM filters for Airband is that they lower the noise floor across the band. This usually will let you lower the squelch which leads to more hits and better scanning across the band.
This is especially useful for sensitive receivers.

Absolutely so, I made this comment a few posts back.

 

[lw3haz]

Unfortunately, the specifications show that they cut out the 80-108mHz band, i.e. the band that cuts into neighboring frequencies. Music plays at a frequency of 124mHz, which is far beyond the operating range of this filter.

Welcome to the world of FM QRM. I live very near several several several transmitters and have been analizing the problem. Here are some of the conclusions:

1. The signal I heard - all over VHF - were clearly result of intermodulation (harmonics of signals mixing somewhere. Eg. if you have a transmitter at 100 MHz and another one at 90 MHz, then you will - if the signals are strong enough - hear a signal at the sum and difference: 190 and 10 MHz. Stronger signals will produce 2*f1 - f2, and 2*f2 - f1, in this case 2*100-90 (110 MHz) and 2*90 - 100 (80 MHz).
And so on...

2. It does not stop there. Your FM receiver might convert the input (eg 100.1 MHz into 10.7 MHz, but will also receive 10.7*2 MHz
higher... you might hear a transmitter at 100.1Mhz at 100.1+2*10.7 MHz (121.5 MHz). In your case, 124 MHz - 21.4 = 102.6 MHz.

3. I desperately needed an FM band stop filter, as the signals were very strong. So I build a 5th order bandstop filter for 88-108 Mhz, which would ideally attenuate the signals about 40-50 dB. The filter worked well, but it seemed to attenuate not all signals equally.

4. My actual suspect is that the FM transmitters, which are in close proximity to _each other_ (in the same tower!), are generating this intermodulation themselves, so they are generating the mixes and are transmitting them. In this case, no filter at my (or your) end can eliminate them, not without attenuating the _wanted_ signal.

In your case, I suspect case 2. Just because the 124 MHz you reported suspiciously points to 2 times 10.7 MHz. Read the frequency more precisely, subtract 21.4, and check if that frequency corresponds to a local (or strong) FM signal. You will hear the music badly. because the modulation is too wide.

 

[G7RUX]

I would be surprised if the FM transmitters are generating the intermodulation products themselves since this would tend to result in discrete products. You indicated that you were hearing music all across the band so I would suspect the intermods are being generated within the receiver, caused by the strong FM signals; an FM band stop filter will likely help quite a bit.

I use a Yaesu VR5000 that was doing pretty much this, with a raised noise floor everywhere and I live a couple of kilometres from high power FM broadcast stations (6 on one site) and a band stop filter helped an awful lot.