RE: [Repeater-Builder] Alcatel Isolator Panel * 148-164 Mhz
As Bob, NO6B mentioned below, a properly designed wideband VHF isolator can cover the whole VHF highband spectrum. A properly aligned tunable version in either VHF or UHF, 98% of the time, will have lower forward insertion loss, higher reverse isolation and better return loss numbers, all very desireable attributes. Although a wideband version may sound nice, remeber it is a comprise in performance. Steve / K6SCA --- On Tue, 3/3/09, n...@no6b.com n...@no6b.com wrote: From: n...@no6b.com n...@no6b.com Subject: RE: [Repeater-Builder] Alcatel Isolator Panel * 148-164 Mhz To: Repeater-Builder@yahoogroups.com Date: Tuesday, March 3, 2009, 7:53 PM At 3/3/2009 19:15, you wrote: Jim, Some manufacturer' s catalogs for ferrite isolators are misleading. When any manufacturer states that his model xxx is available for 136-174 MHz (for example), it does NOT mean that you can field-tune that product to operate anywhere within the 136-174 MHz band. It is not often clearly stated that the firm can MAKE an isolator to operate on a fixed frequency within the 136-174 MHz range, but once made, that isolator has a very narrow field-tuning range of perhaps 3 or 4 MHz. They're a little wider than that. I have several isolators originally made for the 151-154 range that tuned down to 145 MHz quite nicely. UHF isolators made for 460-465 MHz typically tune down to 445 MHz with no problems. I wish I had a nickel for every Ham who bought a ferrite isolator that was manufactured to operate at a commercial frequency, but found that it would not work at all in the 2m band. Despite what some folks allege, a ferrite isolator must normally be remanufactured to move its operating frequency more than a few MHz. A case in point: A local radio club was donated a mint-condition Sinclair dual isolator that was tuned to 162.5125 MHz. Such an isolator costs about $550 new. The club shipped the unit to Sinclair for a factory rebuild to operate at a 147 MHz frequency. It cost about $250 for this work, but the modified unit worked perfectly at the 2m frequency, and it has a new-unit warranty. There is a lot of precision machining that is required to perform a rework; it is far more than a simple retuning. Anyone who tells you anything different is woefully misguided, and obviously knows nothing about how isolators are constructed! Well, there is such a thing as a wideband isolator. I once had one that covered the entire VHF HB with no tuning. They are typically much bigger than the tunable units, at least at VHF are probably more expensive, hence much rarer of a find. Bob NO6B
RE: [Repeater-Builder] Alcatel Isolator Panel * 148-164 Mhz
Jim, Some manufacturer's catalogs for ferrite isolators are misleading. When any manufacturer states that his model xxx is available for 136-174 MHz (for example), it does NOT mean that you can field-tune that product to operate anywhere within the 136-174 MHz band. It is not often clearly stated that the firm can MAKE an isolator to operate on a fixed frequency within the 136-174 MHz range, but once made, that isolator has a very narrow field-tuning range of perhaps 3 or 4 MHz. I wish I had a nickel for every Ham who bought a ferrite isolator that was manufactured to operate at a commercial frequency, but found that it would not work at all in the 2m band. Despite what some folks allege, a ferrite isolator must normally be remanufactured to move its operating frequency more than a few MHz. A case in point: A local radio club was donated a mint-condition Sinclair dual isolator that was tuned to 162.5125 MHz. Such an isolator costs about $550 new. The club shipped the unit to Sinclair for a factory rebuild to operate at a 147 MHz frequency. It cost about $250 for this work, but the modified unit worked perfectly at the 2m frequency, and it has a new-unit warranty. There is a lot of precision machining that is required to perform a rework; it is far more than a simple retuning. Anyone who tells you anything different is woefully misguided, and obviously knows nothing about how isolators are constructed! 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Jim Cicirello Sent: Tuesday, March 03, 2009 8:28 AM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Alcatel Isolator Panel * 148-164 Mhz For those of us who missed the boat or bid on the lower frequency Alcatel Isolator Panels on E-Bay, I see the seller has more at a higher operating frequency 148-164. My question to Skipp and others who are familiar with these is: For those of us who have Ham Transmitters in the 147 MHz 2-meter Band, are these close enough to work? Also mare they tunable or fixed for the entire range? Thanks in advance for the guidance. 73 JIM KA2AJH
RE: [Repeater-Builder] Alcatel Isolator Panel * 148-164 Mhz
At 3/3/2009 19:15, you wrote: Jim, Some manufacturer's catalogs for ferrite isolators are misleading. When any manufacturer states that his model xxx is available for 136-174 MHz (for example), it does NOT mean that you can field-tune that product to operate anywhere within the 136-174 MHz band. It is not often clearly stated that the firm can MAKE an isolator to operate on a fixed frequency within the 136-174 MHz range, but once made, that isolator has a very narrow field-tuning range of perhaps 3 or 4 MHz. They're a little wider than that. I have several isolators originally made for the 151-154 range that tuned down to 145 MHz quite nicely. UHF isolators made for 460-465 MHz typically tune down to 445 MHz with no problems. I wish I had a nickel for every Ham who bought a ferrite isolator that was manufactured to operate at a commercial frequency, but found that it would not work at all in the 2m band. Despite what some folks allege, a ferrite isolator must normally be remanufactured to move its operating frequency more than a few MHz. A case in point: A local radio club was donated a mint-condition Sinclair dual isolator that was tuned to 162.5125 MHz. Such an isolator costs about $550 new. The club shipped the unit to Sinclair for a factory rebuild to operate at a 147 MHz frequency. It cost about $250 for this work, but the modified unit worked perfectly at the 2m frequency, and it has a new-unit warranty. There is a lot of precision machining that is required to perform a rework; it is far more than a simple retuning. Anyone who tells you anything different is woefully misguided, and obviously knows nothing about how isolators are constructed! Well, there is such a thing as a wideband isolator. I once had one that covered the entire VHF HB with no tuning. They are typically much bigger than the tunable units, at least at VHF are probably more expensive, hence much rarer of a find. Bob NO6B
