More radio stuff

[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.