More radio stuff

[teejk]

I will apologize in advance for not searching/appending older threads on this topic. I find that I listen to much more radio now than I watch TV. Just me. So here's my story. I have a metal shop building (inside and out). I have 2 long strips (24' each) of T8 fluorescent lights on separate switches spaced 10' apart and 10' from each sidewall. FM signals were easy with a simple external wire outside the shop. AM was always "iffy" depending on weather but for a few years my Milwaukee job site radio would work with its internal AM antenna. Might have been a voltage spike or something but it stopped performing on AM. So I bought a good AM/FM external "spike" antenna and mounted it on a 16' mast outside the shop. The tip extends well above the metal shop roof line and the mast itself sits about a foot away from the building. Single RG6 cable that comes into the building and connects to a splitter (supplied by the antenna people) inside the building. Also bought a new receiver (Pyle Audio). That unfortunately had the antenna connections with those little spring loaded clips that require a coax to twin lead adaptor on both the AM and FM sides. I can get pretty good reception on the FM (other than that adaptor can be fussy). The AM side though is giving me problems. The leads on the adaptor are maybe 22ga wire and if I "fiddle" with it the signal will go from "ok" to "nothing" so I suspect the problem lies with that adaptor and/or how it works with the receiver. I have tried both vanilla and quad shield cable. I'll leave the question at that for now.

 

[Industrial Toys]

I kind of lost you. But the important thing is that the impedance is maintained. Or a matching transformer is used if the impedance is changed. The RG 6 is 75 ohm and I hope the antenna is as well. The terminals on the radio are probably 300 ohm (balanced) and would need a transformer to match to 75 ohm. The manual should tell you the input specs.

I would probably think about a lightning arrestor as well.

 

[teejk]

Thanks. I checked the receiver manual and don't see any input specs. The antenna (DX Engineering) instructions show things exactly as I described RG6 from antenna to splitter, one coax to a F to twin lead adaptor (supplied) to the AM antenna terminals, another coax to a separate twin lead adaptor that I purchased locally (antenna mfgr assumed a coax input for FM). I think the problem lies in the supplied twin lead adaptor. Pretty thin wire compared to the size of the antenna inputs and if I "fiddle" with it, it seems to work but seems to be very fussy in how it is positioned. Guess I'll contact the receiver maker and see if they have any ideas. Barring that maybe I'll hit the leads with a bit of silver solder to give them some structure.

 

[dickfoster]

I will apologize in advance for not searching/appending older threads on this topic. I find that I listen to much more radio now than I watch TV. Just me. So here's my story. I have a metal shop building (inside and out). I have 2 long strips (24' each) of T8 fluorescent lights on separate switches spaced 10' apart and 10' from each sidewall. FM signals were easy with a simple external wire outside the shop. AM was always "iffy" depending on weather but for a few years my Milwaukee job site radio would work with its internal AM antenna. Might have been a voltage spike or something but it stopped performing on AM. So I bought a good AM/FM external "spike" antenna and mounted it on a 16' mast outside the shop. The tip extends well above the metal shop roof line and the mast itself sits about a foot away from the building. Single RG6 cable that comes into the building and connects to a splitter (supplied by the antenna people) inside the building. Also bought a new receiver (Pyle Audio). That unfortunately had the antenna connections with those little spring loaded clips that require a coax to twin lead adaptor on both the AM and FM sides. I can get pretty good reception on the FM (other than that adaptor can be fussy). The AM side though is giving me problems. The leads on the adaptor are maybe 22ga wire and if I "fiddle" with it the signal will go from "ok" to "nothing" so I suspect the problem lies with that adaptor and/or how it works with the receiver. I have tried both vanilla and quad shield cable. I'll leave the question at that for now.

Just so you know the frequency is very different for FM and AM radio signals. Antennas are made to perform within a certain range of frequencies so one made for FM will provide crappy performance for AM and vice versa. It doesn't matter what the manufacture claims because it's dictated by the laws of physics. FM signals are also horizontally polarized and line of sight signals while AM is mostly vertical and a ground wave signal. Often a long hunk of wire strung up will do the job for an AM receiver. Due to the popularity of FM and it's improved noise performance, stereo etc, later day AM radios just aren't what they used to be. Most makers just throw something in there to put AM on the label but do little to optimise the design or performance for AM. Older AM radios will typically outperform later units by a wide margin.
You could try one of these
Tecsun AN-1 Tunable AM/MW Antenna (No Battery/No Antenna Jack Needed) | eBay
made specifically for AM but you'd likely be better off with an external long wire for your AM radio. Run the wire out far enough then run it up or down a tree or something to get the best AM reception.
http://hyperphysics.phy-astr.gsu.edu/hbase/audio/radio.html

 

[teejk]

Just so you know the frequency is very different for FM and AM radio signals. Antennas are made to perform within a certain range of frequencies so one made for FM will provide crappy performance for AM and vice versa. It doesn't matter what the manufacture claims because it's dictated by the laws of physics. FM signals are also horizontally polarized and line of sight signals while AM is mostly vertical and a ground wave signal. Often a long hunk of wire strung up will do the job for an AM receiver. Due to the popularity of FM and it's improved noise performance, stereo etc, later day AM radios just aren't what they used to be. Most makers just throw something in there to put AM on the label but do little to optimise the design or performance for AM. Older AM radios will typically outperform later units by a wide margin.
You could try one of these
Tecsun AN-1 Tunable AM/MW Antenna (No Battery/No Antenna Jack Needed) | eBay
made specifically for AM but you'd likely be better off with an external long wire for your AM radio. Run the wire out far enough then run it up or down a tree or something to get the best AM reception.
http://hyperphysics.phy-astr.gsu.edu/hbase/audio/radio.html

Thanks for the info. The antenna I bought (DXE-AFHD-4) tested for 80 miles on FM, 90 miles on AM. "Fiddled" around some more today and found that the sound was great (AM/FM) if I DIDN'T connect the negative leg of the twin lead adaptors to the negative antenna ports on the receiver. My shop is metal inside and out and my electrical runs are flush mounted EMT with 2 duplex outlets mounted every 10' where the EMT also serves as the grounding system. I've checked for potential "stray"voltage everywhere and have found none. I mounted the splitter inside the building since I already had my "red-neck" wire loop outside for my old receiver and used the existing outside RG6 for that. Time to contact both the antenna guys and the receiver guys I guess. Connecting those tiny ground wires to the back of the receiver and losing the signal tells me that something ain't right.

 

[Oaktree]

FM signals are also horizontally polarized and line of sight signals

Actually, most FM signals are circularly polarized and will work with either vertical or horizontal antennas.

 

[PILOON]

Most effective antennas are 1/4, 1/2 or full wave length and there are formulas to calculate that.
For FM you are near TV low band so often a splitter works here.
For AM generally a long wire works if oriented properly. (like spread your arms facing the station)

 

[teejk]

Most effective antennas are 1/4, 1/2 or full wave length and there are formulas to calculate that.
For FM you are near TV low band so often a splitter works here.
For AM generally a long wire works if oriented properly. (like spread your arms facing the station)

Glad to get some input on this...but here's the specs on the antenna (all wasted on me because I was an accountant in a previous life)...Antenna length 48"...Antenna beam width Omni-directional...AM capture length 300 inches...Ground plane required None...AM/FM band separator FM rejection on AM band >50 dB...AM rejection in FM band >60 dB AM/FM....Pass-band loss: <1 dB load impedance :300 ohms...FM load impedance 75 ohms. That is the antenna I bought. It came with the splitter and a coax to twin lead adaptor that according to their diagram went to the AM connections (red to +, black to -). As noted above, everything works great IF I leave that black wire out. Based on the above, guessing that supplied adaptor somehow converts from 75ohms to 300 ohms (or perhaps that is in the splitter) but again I don't understand any of this stuff.

 

[Industrial Toys]

My newer expensive vapor tight flourescent lights in my wood shed cause me RFI. Also a structural steel building. I bought the same ones for a friends shop and we ordered (and paid for) premium ballasts. They were still noisy, so my friend in the elect. dist. bus. got us new ballasts and we changed them all out. Nice and quiet now. I should change mine too.

If the RFI is so great as to desensitize the receiver, no practical antenna will solve the problem.

And, as far as antenna distance specs go. That assumes a (mostly) clear line of sight. EDITED, Meaning FM (of course) VHF being the limiting factor, not the modulation.

 

[k0ua]

I would be extremely concerned if I could only receive AM broadcast band signals up to 90 miles away.

At least at night you should be able to receive signals from at least several hundred to several thousands of miles.

Even during the day time you should be able to receive the 50 Kilowatt clear channel stations a couple of hundred miles away at least.

I am always amused by manufacturers placing a number on how far you can receive a signal on their antenna's. But people ask such questions. There is no correct milage answer. The correct answer is "it depends" FM broadcast band (88-108 MHz) can easily propagate for several thousands of miles via one of many different propagation modes. E layer propagation is very common. AM broadcast band signals can easily propagate all the way around the earth under some conditions. During grey line conditions where the terminator is near your location and the transmitting stations location, it is possible to receive a signal both long path and short path. Yes that is right, a signal that has went all the way one direction around the earth and a corresponding signal that has taken a shorter path partially around the earth to your location. I have personally "worked" amateur radio stations with simultaneous long path and short path signals. It makes for an interesting "echo" to hear the long path signal come in a fraction of a second after the short path signal arrives.

Yes, I know the "estimates" that manufactures publish on Antennas are figures for "average" ground wave propagation modes with some sort of "average" installation with some sort of "average" receiver, with some sort of "average" local noise level. As if there was actually some sort of thing as "average".

But people want simple answers to very complex questions. Like "how far can you talk on that thing?" There is no simple answer. So Manufactures will make one up.

 

[Industrial Toys]

Is E layer propagation, temperature inversion? I am guessing not.

I have bought several good and bad consumer type, antenna tuners at thrift stores. The good old ones from the 70s are even in a wooden box. I never got one of those nice (sleuth)(sp?) units yet. They all work a bit, and if you don't change stations often, they improve your signal enough to make them worth the bother.

 

[k0ua]

Glad to get some input on this...but here's the specs on the antenna (all wasted on me because I was an accountant in a previous life)...Antenna length 48"...Antenna beam width Omni-directional...AM capture length 300 inches...Ground plane required None...AM/FM band separator FM rejection on AM band >50 dB...AM rejection in FM band >60 dB AM/FM....Pass-band loss: <1 dB load impedance :300 ohms...FM load impedance 75 ohms. That is the antenna I bought. It came with the splitter and a coax to twin lead adaptor that according to their diagram went to the AM connections (red to +, black to -). As noted above, everything works great IF I leave that black wire out. Based on the above, guessing that supplied adaptor somehow converts from 75ohms to 300 ohms (or perhaps that is in the splitter) but again I don't understand any of this stuff.

Let me take a stab at turning technical speak to english.
Antenna Length. 48 inches.. That one should be self explanatory.
AM capture length. sounds like a made up BS figure to me. Because an AM broadcast band Dipole that is resonant lets say at 1 MHZ (1000 Khz) which would be about in the middle of the broadcast band should be about 468 feet long. Notice I picked an easy frequency I could calculate in my head

Ground plane required: none. They are saying you don't need to install any 1/4 wave ground radials. Good thing because the AM ones for a full size 1/4 wave vertical would need to be about 234 feet long each.
On the AM/FM "splitter" they are saying that the rejection of each type of signal is greater than 50 decibels and greater than 60 decibels. Fairly decent separation of the two bands. The decibel scale is logarithmic in nature. Just like our ears. Without confusing you even more about db scales. Just remember that for every 10 db of gain or loss your are increasing or decreasing the power in that circuit by a factor of 10. So lets say you started with a 1 watt signal, now you put it thru an amplifier to increase its power, and that amplifier had 10 db of gain. That signal out of the amplifier is now 10 watts. But now lets say the amplifier had 20 db of gain. Now the output signal is 100 watts while the input signal is still the 1 watt. So 30 db of gain would be 1000 watts out and 40 db of gain would be 10,000 watts and 50 db of gain would be 100,000 watts out of our big honking amplifier. I hope that helped some.

Pass-band loss. : They are saying the splitter device will lose less than 1 decibel of signal on either band by its inherent losses from its components. 1db of loss is very little loss. Most people cannot detect the loss of 1 db of signal. Standard "S" meters in communications receivers are supposed to be calibrated in 6DB increments. So this is way less than 1 "S" unit.

Output Load impedance: They are saying the output load impedance of the AM side of this device is 300 ohm balanced output. This is a common "twinlead" balanced transmission line impedance. The FM side is a 75 ohm unbalanced output. This is a common coaxial cable (coax is always unbalanced) impedance. Note that you can easily transform a 300 ohm balanced impedance to a 75 ohm unbalanced impedance with a simple 4 to 1 Balun. A Balun is a contraction of the words Balanced to Unbalanced. And with a 4 to 1 ratio transformer the 300 is transformed to 75 also at the same time. Of course there are 1 to 1 and many other types of Baluns. But a common 4 to 1 300 to 75 ohm balun is commonly used .

So there, I wrote you a book and we did not cover even 1% of what you need to know about antennas and feedlines, not to mention radio wave propagation or how to compare receivers... These subjects could literally fill your book shelf. And you can quite literally spend a lifetime learning these things, and still not know it all. I know enough to know I don't know much.

 

[teejk]

Forgot to mention...my previous receiver was a Sony that I bought for $$$ when I was working in the UK. Have had it in the shop connected to a 220/110 transformer. Was a nice unit in its day. Had 2 AM bands (high and low) on it that I guess are wasted here...the UK apparently was late to the game on FM and relied on AM. That lower band was a total waste here (I think we start at 500KHz and that band ended before that). The higher band was preset and I could never dial in the stations I wanted (e.g. if I wanted 550, I could get 540 or 560). Anybody that wants it can have it.

 

[k0ua]

Is E layer propagation, temperature inversion? I am guessing not.

I have bought several good and bad consumer type, antenna tuners at thrift stores. The good old ones from the 70s are even in a wooden box. I never got one of those nice (sleuth)(sp?) units yet. They all work a bit, and if you don't change stations often, they improve your signal enough to make them worth the bother.

No you are referring to Tropospheric bending with a temperature inversion. This occurs in the troposphere not the ionosphere.

E layer ionispheric propagation occurs "sporadically" when the E layer forms. This is often referred to as sporadic E. It will not always form all the way up to 88-108 Mhz it is much more common down around 50 Mhz (the "magic" 6 meter band) during the months of May thru August and in November/December.

 

[Industrial Toys]

I only ever experienced enhancements on VHF (including 88-108) as a result of inversion.

Anyway, It's quite obvious what the OP has to do. Get a high speed connection and stream his entertainment.

 

[k0ua]

I only ever experienced enhancements on VHF (including 88-108) as a result of inversion.

Anyway, It's quite obvious what the OP has to do. Get a high speed connection and stream his entertainment.

TEP is another propagation mode. Trans Equatorial Propagation. Again these modes are more common on 50Mhz and below, but they do occur up in the FM broadcast band.

 

[Industrial Toys]

I used to have a remote base on 6 meter FM. GE Mastr Exec II ?, with a tube final. It was always exciting as to when that thing would come alive and you never knew who would be on the other end.

 

[teejk]

Let me take a stab at turning technical speak to english.
Antenna Length. 48 inches.. That one should be self explanatory.
AM capture length. sounds like a made up BS figure to me. Because an AM broadcast band Dipole that is resonant lets say at 1 MHZ (1000 Khz) which would be about in the middle of the broadcast band should be about 468 feet long. Notice I picked an easy frequency I could calculate in my head

Ground plane required: none. They are saying you don't need to install any 1/4 wave ground radials. Good thing because the AM ones for a full size 1/4 wave vertical would need to be about 234 feet long each.
On the AM/FM "splitter" they are saying that the rejection of each type of signal is greater than 50 decibels and greater than 60 decibels. Fairly decent separation of the two bands. The decibel scale is logarithmic in nature. Just like our ears. Without confusing you even more about db scales. Just remember that for every 10 db of gain or loss your are increasing or decreasing the power in that circuit by a factor of 10. So lets say you started with a 1 watt signal, now you put it thru an amplifier to increase its power, and that amplifier had 10 db of gain. That signal out of the amplifier is now 10 watts. But now lets say the amplifier had 20 db of gain. Now the output signal is 100 watts while the input signal is still the 1 watt. So 30 db of gain would be 1000 watts out and 40 db of gain would be 10,000 watts and 50 db of gain would be 100,000 watts out of our big honking amplifier. I hope that helped some.

Pass-band loss. : They are saying the splitter device will lose less than 1 decibel of signal on either band by its inherent losses from its components. 1db of loss is very little loss. Most people cannot detect the loss of 1 db of signal. Standard "S" meters in communications receivers are supposed to be calibrated in 6DB increments. So this is way less than 1 "S" unit.

Output Load impedance: They are saying the output load impedance of the AM side of this device is 300 ohm balanced output. This is a common "twinlead" balanced transmission line impedance. The FM side is a 75 ohm unbalanced output. This is a common coaxial cable (coax is always unbalanced) impedance. Note that you can easily transform a 300 ohm balanced impedance to a 75 ohm unbalanced impedance with a simple 4 to 1 Balun. A Balun is a contraction of the words Balanced to Unbalanced. And with a 4 to 1 ratio transformer the 300 is transformed to 75 also at the same time. Of course there are 1 to 1 and many other types of Baluns. But a common 4 to 1 300 to 75 ohm balun is commonly used .

So there, I wrote you a book and we did not cover even 1% of what you need to know about antennas and feedlines, not to mention radio wave propagation or how to compare receivers... These subjects could literally fill your book shelf. And you can quite literally spend a lifetime learning these things, and still not know it all. I know enough to know I don't know much.

I understand (maybe). I happen to like a lot of stuff only available on the AM side (e.g. Gary Sullivan home improvement stuff)...I know AM is becoming a dinosaur. I use my truck as a gauge of what type of signal I can expect to get in my shop (weather, clouds, output from the stations, etc.). In fact my first thought was to install a car radio and antenna with a 120v/12v converter because my truck radio is usually pretty good. My new set-up is pretty good also as long as I don't touch either "-" leads to their respective terminals on the back of the receiver. Still don't understand why that would be.

 

[k0ua]

I used to have a remote base on 6 meter FM. GE Mastr Exec II ?, with a tube final. It was always exciting as to when that thing would come alive and you never knew who would be on the other end.

Yep, that was most likely Sporadic E. Remember that SSb will have several db of "gain" over FM on the receiving end with equal power outputs. So much weaker signals can be heard and understood at the expense of "fidelity" that FM signals have.

 

[k0ua]

I understand (maybe). I happen to like a lot of stuff only available on the AM side (e.g. Gary Sullivan home improvement stuff)...I know AM is becoming a dinosaur. I use my truck as a gauge of what type of signal I can expect to get in my shop (weather, clouds, output from the stations, etc.). In fact my first thought was to install a car radio and antenna with a 120v/12v converter because my truck radio is usually pretty good. My new set-up is pretty good also as long as I don't touch either "-" leads to their respective terminals on the back of the receiver. Still don't understand why that would be.

Could you draw a simple drawing or a series of detailed photos of how your hookup is from the antenna to the radio. Perhaps something would jump out at us. Also keep in mind that automobile radios are usually a cut above any consumer radio you could find easily. Not counting communication grade or amateur radio equipment. A typical automotive radio will have a tuned RF stage and a good noise limiter section.