Home |
Search |
Today's Posts |
#4
![]() |
|||
|
|||
![]()
On Jun 26, 1:16*am, m II wrote:
- Anyone have a way of measuring the varying - efficiencies of the following? - Let's say 5 to 20 MHz frequency range. - - This would be the base number for comparison, assign it a one: - - a: Straight connection of a random long wire antenna OK so this is your starting point "Basic Standard" with an assigned Unit Value of One [1] Therefore this is not about 'efficiency' but Relative Merit. - The others... - - b: The same long wire connected through - a television (75/300 ohm variety) Depends on the relative quality a design of the TV Matching Transformer. Plus the quality of the Coax Cable and a good earthen Ground. 1 - A 'good-one' will reduce some of the apparent noise coming from the basic long wire antenna : So that is a +One-Half [+1/2] 2 - A 'good-one' will reduce some of the AM/MW Band Signals coming from the basic long wire antenna : So that is a +One-Half [+1/2] Relative Merit Unit Value of One + One-Half + One-Half for a Total of Two [2] --- to One - c: Same antenna with a 9:1 ratio transformer First most of the very broadband 9:1 Matching Transformers that are shown for Shortwave Radio Listening (SWL) are also designed to cover the AM/MW/BCB down to 500 kHz and SW Bands up to 30 MHz. These usually recommend about a 10-Turn Primary for the Feed-Line to the Radio and about a 30-Turn Secondary for the Antenna side. Note - That you set a 5 MHz lower 'limit' so you might want to cut the number of turns in half and have a 5 -Turn Primary with a 15 Turn Secondary. A good 9:1 Matching Transformer : 1 Will reduce much of the apparent noise coming from the basic long wire antenna : So that is a +One [+1] 2 - Will reduce much of the AM/MW Band Signals coming from the basic long wire antenna : So that is a +One [+1] Relative Merit Unit Value of One + One + One for a Total of Three [3] --- to One - I'm assuming everything else remaining the same. As am I : Same Long Wire Antenna +plus+ * Same good earthen Ground# # Note - Many SWL'ers only use an in the house Water Pipe Ground with their Long Wire Antenna -so- Going from an in the house Water Pipe Ground to a good outside 8-Ft earthen Ground Rod may be another +One [+1] all by itself for those who make the switch to an outside 8-Ft earthen Ground Rod. * Same Coax Cable# # Note - Many SWL'ers only use an Insulated Wire for their Feed-in-Line from their Long Wire Antenna -so- Going from an Insulated Wire to a Coax Cable may be another +One [+1] all by itself for those who make the switch in the Feed-in-Line. - I'm interested in the variation, shown ratio wise, - between the above. Are there any handy - online calculators for this? Online Calculators will give you Generated Numbers for a given set of parameters; and not Relative Ratios {side-by-side comparisons -aka- Relative Merit} . - - mike iane ~ RHF |
Thread Tools | Search this Thread |
Display Modes | |
|
|
![]() |
||||
Thread | Forum | |||
Question about matching transformer (9:1 un-un) | Shortwave | |||
Looking for matching transformer. | Antenna | |||
An "All-in-One" Slinky Antenna and Matching Auto-Transformer | Shortwave | |||
Building a Matching Transformer for Shortwave Listener's Antenna using a Binocular Ferrite Core from a TV type Matching Transformer | Shortwave | |||
Matching transformer question. | Shortwave |