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Cables for GE Mastr II S3V225UAUHA

bil.isom All Messages By This Member #169268 Thank all of you for the information I have received by reading your mail. I have received a S3V225UAUHA 225 watt VHF repeater.? The rf cables are missing and I need to make new ones.? The 110 watt amplifier is split to feed two 130 watt amplifiers, then combined to feed the duplexer.?? I need to know how to calculate the length of the splitter and combiner cables.? I am assuming the 130 watt amplifiers need to be fed 90 degrees out of phase, but I would like to be sure. I also have a similar UHF repeater that is next on my list. Thank you Bill Isom N4XIR
Jeff DePolo WN3A All Messages By This Member #169281 I need to know how to calculate the length of the splitter and combiner cables. The splitters and combiner are Wilkinsons and are mounted on panels. The cables that go to/from them can be any length PROVIDED that the total length of the cable to and from amplifier A is the same as the total length of cable to/from amplifier B. The goal here is obviously that the RF from both amplifiers has to arrive at the combiner in-phase. The original factory cables were RG213 for whatever it's worth. I'd make them out of something better like RG214 or RG393. --- Jeff WN3A
bil.isom All Messages By This Member #169282 Thank you. I have RG 214 ready to cut. I was thinking the amps needed to be fed out of phase to lessen the load on the power supply.
Joe All Messages By This Member #169283 开云体育 On 9/22/2018 6:36 AM, Bill Isom bil.isom@... [Repeater-Builder] wrote: I was thinking the amps needed to be fed out of phase to lessen the load on the power supply. I thought that Quintron/Glenayre paging transmitters used this technique.? 1/4 wave difference seems to come to mind.? It's been a long time..... Joe
Ray Sohst All Messages By This Member #169284 The only time I've used amplifiers in parallel they had?measured sections?of 75ohm [could have been 1/4 waves] to split into and combine out of the PAs. Just paralleling will present 25ohms to six points in the system which?are presumably expecting to see 50ohms. Having said this I have no experience with this specific system and it?may have been designed for simple paralleling.
Jeff DePolo WN3A All Messages By This Member #169285 I have RG 214 ready to cut. I was thinking the amps needed to be fed out of phase to lessen the load on the power supply. How do you figure? Amplifiers consume DC power. They don't consume RF. The DC current being pulled by an amplifier operating an emission that lacks any amplitude variation (such as FM) will pull the same amount of current at any point in time. It's not like the DC current draw from the power supply varies at an RF rate. If it did, your power cables would likely be radiating more power than your antenna. --- Jeff WN3A
Jeff DePolo WN3A All Messages By This Member #169286 The only time I've used amplifiers in parallel they had measured sections of 75ohm [could have been 1/4 waves] to split into and combine out of the PAs. Ray - if you've never worked on a high-power solid-state VHF or UHF Master II, they come with high-power Wilkinson splitter and combiner external to the PA's. Inside those units are quarter-wave sections of 75 ohm line (RG-302) and the 100 ohm floating resistor. The OP is asking about the length of cables that go to/from the splitters/combiners and the amplifiers which, since everything is already at 50 ohms, can be any length provided that the resulting RF from each PA arrives at the combiner in-phase. --- Jeff WN3A
Ray Sohst All Messages By This Member #169287 Thanks for the update, it all makes sense. Being a 'typical' amateur I'd have been looking at doing the split and combine in the absence of a professional device.
Joe All Messages By This Member #169290 What about a class C amplifier used in FM? Joe toggle quoted message Show quoted text On 9/22/2018 9:30 AM, 'Jeff DePolo' jd0@... [Repeater-Builder] wrote: Amplifiers consume DC power. They don't consume RF. The DC current being pulled by an amplifier operating an emission that lacks any amplitude variation (such as FM) will pull the same amount of current at any point in time.
Jeff DePolo WN3A All Messages By This Member #169291 Amplifiers consume DC power. They don't consume RF. The DC current being pulled by an amplifier operating an emission that lacks any amplitude variation (such as FM) will pull the same amount of current at any point in time. What about a class C amplifier used in FM? That's what I was talking about. While the RF devices are only conducting during a portion of the AC waveform cycle, the collector/drain choke and all of the other filtering (capacitors, inductors) inside the amplifier result in a constant DC current draw from the power supply. That same filtering is what keeps the RF going out the antenna jack rather than causing all of the external DC wiring to radiate RF. In a nutshell, the amplifier as a whole isn't "pulsing" DC from the power supply, it's sucking electronics from the power supply at a constant rate in the case of FM, whether it's class A, B, AB, C, or whatever. --- Jeff WN3A
[email protected] #169294 The only time I've used amplifiers in parallel they had measured sections of 75ohm [could have been 1/4 waves] to split into and combine out of the PAs. Ray - if you've never worked on a high-power solid-state VHF or UHF Master II, they come with high-power Wilkinson splitter and combiner external to the PA's. Inside those units are quarter-wave sections of 75 ohm line (RG-302) and the 100 ohm floating resistor. The OP is asking about the length of cables that go to/from the splitters/combiners and the amplifiers which, since everything is already at 50 ohms, can be any length provided that the resulting RF from each PA arrives at the combiner in-phase. --- Jeff WN3A A few years past, directly behind the Dayton Hamvention, Hara Area Repeater Builder / Jeff / Junk Enders Group, Flea Market location (mouth-full wasn't that) ... one of the surplus everything equipment sellers came up with a cabinet or two, containing beautiful Mastr ii VHF high power repeater/base station(s). Members of this group didn't take long to make a deal and start parting out the systems. A Left Coast Junk Ender's 12 Step Program Member fell right off the wagon for the power combiners Jeff mentions above. The original RF leads (coax) from the splitters to the dual amplifier input jacks was not the same length, same with the output lengths. But the total measured length of the input and output cables to each external amplifiers was the same. If you can get your head around the input cable to amplifier A was the same length as the output cable for amplifier B. The converse of the amplifier A output cable was the same length as the B amplifier input cable. Again, the net cable length of each amplifier path from and back to the splitter/combiners is the same. The splitter and combiner are the same exact circuit, in the GE Mastr ii system, even mounted on the same 19" rack plate... with SO-239 chassis mount coax jacks. Easy enough to make if you able an willing... cheers, Ex Hara Brat Mister, now a Greene County Fairgrounds pork chop sandwich research and quality control person.
Joe All Messages By This Member #169297 skipp, Do you think the specific cable lengths were done for circuit design, or just convenience of cabinet equipment installation? Joe toggle quoted message Show quoted text On 9/22/2018 8:02 PM, skipp025@... [Repeater-Builder] wrote: The original RF leads (coax) from the splitters to the dual amplifier input jacks was not the same length, same with the output lengths. But the total measured length of the input and output cables to each external amplifiers was the same. If you can get your head around the input cable to amplifier A was the same length as the output cable for amplifier B. The converse of the amplifier A output cable was the same length as the B amplifier input cable.
[email protected] #169301 skipp, Do you think the specific cable lengths were done for circuit design, or just convenience of cabinet equipment installation? Joe I try not to think too much... but the answer to your question is just the location in the cabinet. s. On 9/22/2018 8:02 PM, skipp025@... [Repeater-Builder] wrote: > The original RF leads (coax) from the splitters to the dual amplifier > input jacks was not the same length, same with the output lengths. > But the total measured length of the input and output cables to > each external amplifiers was the same. If you can get your head > around the input cable to amplifier A was the same length as the > output cable for amplifier B. The converse of the amplifier A output > cable was the same length as the B amplifier input cable.
[email protected] #169302 Speaking of the Devil.... (GE Mastr ii High Power, Paralleled Amplifiers) Not having read the first portion of the thread, I don't know if this has already been brought up... but, The exact animal we're talking about here is up on Ebay for sale... maybe that's where this thread started from? Anyway, great pictures if you look at the amplifiers, the power combiner splitter panel. EBay item number: 273466569823 GE MASTR ii 225 Watt VHF Repeater Amplifier System Enjoy Ferritronics Tone Panel
Joe All Messages By This Member #169303 On 9/22/2018 11:51 PM, skipp025@... [Repeater-Builder] wrote: Speaking of the Devil.... (GE Mastr ii High Power, Paralleled Amplifiers) Not having read the first portion of the thread, I don't know if this has already been brought up... but, The exact animal we're talking about here is up on Ebay for sale... WARNING!!!! This is a classic attempt of a Junkenders infected person trying to draw you into their ranks.? Your parents warned you about such people. Joe

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