Re: [Repeater-Builder] Narrowbanding
FWIW it would probably be made to workat a price, but for ordinary consumer type Amateur Radios, not really. We have been conditioned to the sub $400 price range radios that do everything, go everywhere and have less than ordinary receivers in them. :-) 73, Jack VK4JRC Sent from my Apple iPad Tablet PC On Aug 3, 2010, at 6:16 AM, MCH m...@nb.net wrote: I was wondering about that myself. A couple of comments on the other aspects: 1. I see this as falling flat on its face. May as well mandate D-STAR. 2. How are the commercial people fitting SNFM in 7.5 kHz channels as they have been doing on VHF? Joe M.
Re: [Repeater-Builder] Re: Simrex - GLB Pre-Selector Pre-Amplifier
Bob, Some of us are geographically disadvantaged when it comes to availability of equipment. Here in rural Australia, anything secondhand for Amateur Repeater construction is rare, shipping of anything is expensive. From what I read on the group, the U.S. Is overloaded with surplus equipment, sometimes at bargain prices. For me to buy and ship that cheap 1/4 wave can and pre-amp would be more expensive than buying a new Simrex Pre-Selector :-) Since this is a hobby for me...not a paid commercial day job I will take the chance on the NF aspect and have my fun experimenting and testing :-) IF the Simrex-GLB product did not perform..the word would spread faster than the Black Plague and no one would buy them 73, Jack. VK4JRC Sent from my Apple iPad Tablet PC On Jul 31, 2010, at 11:30 PM, n...@no6b.com wrote: At 7/30/2010 08:31, you wrote: Re: Simrex - GLB Pre-Selector Pre-Amplifier Yes, but the NF is unpublished unknown. I therefore assume it's poor, maybe 3 dB? Once again, the NF depends on what device arrives in your specific Simrex (aka GLB) Pre-Selector. It wouldn't hurt or be impossible to ask. Nothing new here - same goes for different versions of preamps, i.e. ARR bipolar vs. GaAsFET. A Chip Angle GaAsFET @ UHF has 0.5 dB NF. Put a 1/4 wave pass cavity with 0.5 dB loops in front of it you have a narrow 1 dB NF front-end. I'll take 1 dB NF over 3 dB NF any day. You're actually comparing two different boxes. Nope - comparing GLB vs. GaAsFET/pass cavity combo. I have measured all the original GLB Pre-selectors and their performance values are very realistic (no surprises). Care to publish your results here? I guess it comes back to price too, a 1/4 wave can plus pre-amp will cost more money... GaAsFET preamp is ~$130. I don't think I've ever paid more than $50 for a pass cavity, so the total is ~$100 less than the GLB unit. Reads like you're comparing a new Preamp with a used cavity against the price of a new Simrex (GLB) Pre-selector. That's not really fair... Perfectly fair. Used pass cavities in good condition are plentiful. Can't remember the last time I saw a used GLB or equivalent unit for sale, so I'm simply comparing what's readily available. One of the really nice (and mostly overlooked) items about the Simrex (GLB) unit construction (and operation) is the Post (active) Amplifier Filtering (tuned circuits). For more than one real reason they can be one of the most under reported bacon saver in your fry pan. A single pass cavity usually has enough out-of-band rejection to be totally adequate on its own - no post-preamp filtering needed. Then again, the fact that post-device filtering is used in the GLB makes me worry about the actual selectivity ahead of that device. If there's only 1 or 2 resonators ahead of it, that's not much protection. A 1/4 wave bottle will provide much more rejection ahead of that first amp, and with less loss hence lower NF. IMO the Simrex amplified preselector is a space-saving compromise, nothing more. Bob NO6B
Re: [Repeater-Builder] Re: Simrex - GLB Pre-Selector Pre-Amplifier
Bob, Thanks for info and links:-) I see where you are coming from.. For me, repeaters are a new deal and I am as dumb as a box of rocks, on the subject..that's why I subscribed to the group. My first repeater project is a portable system, so I have to make it compact for commissioning in hard to access locations, read carry the system on motorcycle. The physical size of high spec filters are too large and prone to transport damage, for my concept. With my Hamtronics low current draw boards, mobile filters with pre-selector, small battery solar panel, 7m squid pole and 4dB antenna with accessories all fit easily on my off road motorcycle, which allow me to reach some good potential sites not accessible by 4x4, if needed. 73, Jack. VK4JRC Sent from my Apple iPad Tablet PC On Aug 1, 2010, at 12:00 PM, n...@no6b.com wrote: At 7/31/2010 07:04, you wrote: I don't believe that. But if you want NEW coaxial resonator filters: http://anglelinear.com/filters/coax_filters.html' These are actually a bit smaller than your typical cavity resonator, they're very low loss. Apparently Chip decided to tradeoff a bit of Q to keep the loss low. But with 2 resonators you end up with a very low system NF selectivity only a bit less than the GLB (which is misleading, as I explained in my previous post because some of that selectivity is after the preamp, so it's still partially susceptible to OOB overload). If you factor in the ham discounts, the total for the dual coaxial resonator/preamp combo is a bit more than the Simrex preselector. But we KNOW the NF will be ~1.1 dB, we KNOW that ALL of the preselection will be ahead of the preamp, so with that info we can properly design a RX system. The Simrex units are made in the US, so you still have to pay to have it shipped down unduh. IF the Simrex-GLB product did not perform..the word would spread faster than the Black Plague and no one would buy them Not saying it doesn't work, but I am saying as an RF engineer that it's impossible with the data in hand to properly apply it's use in a repeater system. Bob NO6B
Re: [Repeater-Builder] Re: Simrex - GLB Pre-Selector Pre-Amplifier
Well, I have decided to buy and try a Simrex Pre-Selector,experiment with it, test it...whatever. At the very least I will learn something from my experiences and it may end up being useful to me, anyway. I certainly appreciate the different points of view here and have learn't of alternative methods and the reasoning behind them. For me, all of it is good information :-) 73, Jack. VK4JRC Sent from my Apple iPad Tablet PC On Jul 31, 2010, at 8:53 AM, skipp025 skipp...@yahoo.com wrote: Re: Simrex - GLB Pre-Selector Pre-Amplifier Kevin Custer kug...@... wrote: What you are missing is that ANY losses ahead of the first active stage add to the noise figure of the system - directly. What we have here is... failure to communicate... (a line from a famous movie). Actually I was trying to high-lite the active device Noise Figure comparison and the lower spec'd gain value of (at least) the GasFET GLB was mostly from the insertion loss of the Pre and Post Filtering. So, while filtering exists in the GLB device, so does loss, and this loss is more than what is experienced when using a quality large diameter cavity. Sure... but again we are comparing a box to another box and they are not the same device. Please allow me to paste some of the text from a recent post (by me). [pasted text] The Simrex (aka GLB) units are actually amplified pre-selector assemblies, not just plain wide-band Receive Pre-Amplifiers. [end of pasted text] Many times Skipp you tell us there is no free lunch, and the same applies to the comparison of selectivity and loss between the GLB and a quality cavity followed by a good active stage. Correct... and a Simrex GLB Pre-Selector should really not really be directly compared to a cavity followed by a good active stage. The Simrex GLB box is more of a true Pre-Selector layout and contains post amplifier filtering. To better equate a similar layout would have you add at least one or more cavities after the active device. And yes we should clearly acknowledge the hopefully obvious lower loss through a higher Q Quality Cavity. Real world test. Take a Hamtronics receiver (no preamp) and do a basic bench sensitivity test to obtain a baseline. If you find something around -123 dBm your in the right ballpark. Now install a bi-polar GLB preselector/preamp in front and measure the sensitivity again - you'll find you have lost several dB of bench sensitivity - at least 3 or 4 dB. Take the same receiver and add a quality 1/4 bottle with a good preamp (your choice - something with 1.5 dB NF or less) and do the test again. Now, the receiver hears at -123 to -127 dBm (dependent mainly upon the quality of the preamp that follows) because the filter hasn't severely ruined the system NF ahead of the first active stage. Even though the GLB has gain, the noise figure of the design has already determined the sensitivity that will be realized by the receiver that follows. The primary land mine in the above comparison is the Now install a bi-polar GLB preselector/preamp. Remember Simrex and GLB offer or did offer a GasFet version of their Pre- selector box. Separate the above in the proper context and the focus should be on the filtering in front of the same type of active device. No one here should discount the higher Q cavity will be the better spec. But again even a high Q cavity with a same or similar active trailing device is still not the same box as the Simrex GLB Pre-selector. You should account for the Simrex GLB integrated post active device filtering. The GLB preselector/preamp should not be considered for adding basic sensitivity, Did anyone make that claim? because it's possible (depending on how good the receiver is to begin with) the opposite will happen - You are correct. however, it will protect a receiver that lacks good front-end filtering, like the Hamtronics. Like everything, the situation helps to dictate what equipment will give the best results. We agree and it's a Friday... Mark today on your calendar. What more could anyone ask for? Kevin cheers, skipp
Re: [Repeater-Builder] Fw: TKR750 -Preamp
This unit looks like the answer for me..I think! I am in the process of building 2 repeaters on 70cm for possible emergency use by our Amateur Radio Club. Both will be very portable, I have Vertex VX-2200 radios for one, Hamtronics T304/R306 boards for the other. In keeping the units very portable, I am using these filters http://www.polarelectronicindustries.com/model.php/model_id/983/ These filters are being used due to portability, but I have reservations about performance IF my systems end up sited close to other equipment. Would the Simrex unit offer advantages when used with my filters? I would look to getting the higher selectivity spec, in preference to gain. 73, Jack. VK4JRC Sent from my Apple iPad Tablet PC On Jul 30, 2010, at 6:20 AM, Steven M Hodell st...@shodell.net wrote: More great info from Frank @ SIMREX. Steve ~ KA1RCI - Original Message - From: Frank Neuperger To: fr...@simrex.com Cc: Steven M Hodell ; maqui Mike Aquilino ; sa...@simrex.com Sent: Thursday, July 29, 2010 4:15 PM Subject: Re: [Repeater-Builder] Fw: TKR750 -Preamp Steve, That did not post to the list because I don't have membership. I would appreciate if you would forward to the list on my behalf. Regards Frank On 7/29/2010 3:58 PM, Frank Neuperger wrote: Steven, Thanks for the vote of confidence. We sell them to Hams (Ham frequencies) for $275($25 less than 2-way dealers) as a gesture to Gil Boelke (silenet key) who developed the preselector and founded GLB (now owned by SIMREX). Note that the standalone preselector is still made in house by staff that were trained by Gil and on tooling built by Gil. It is also the front end of every SNRDS-II radio. Same radios that are part of many FAA and other Federal systems. Standard gain is 8 db For +$25, you can order it with ~4 dB gain and steeper skirts on the filter or ~11 dB gain and gentler slope on the filter skirts. For extreeme interference, one usage of the preselector has been to place a coax stub notch filter between the antenna and the preselector. I have done ~3MHz spacing of the notches of the comb for a marine radio BASE application using ~ 35?? feet of LMR 400 for my stub. One of the notches was placed directly onto the frequency of collocated marine base station giving us an extra 22dB of suppression at that frequency.Using excessive length of coax resulting in a comb allows the overallbandwidth to repeak steeply and with minimal loss between the notches of the comb. A single notch approach (not a comb) when placed close to your desired carrier will often have unacceptable insertional loss at your desired frequency.The comb notch filter is just extra coax and minimizes the insertion loss close to the notch. . The calcs for length are not too difficult. Warmest Regards Frank Neuperger Simrex Corporation VE3FNZ - Original Message - From: Steven M Hodell To: Repeater-Builder@yahoogroups.com Cc: sa...@simrex.com Sent: Thursday, July 29, 2010 2:34 PM Subject: Re: [Repeater-Builder] Fw: TKR750 -Preamp Another very good choice for this application is the GLB Preselector / Preamp from Simrex Corp. I have several of these deployed on 144 / 220 / 440 Amateur repeaters and they all perform very well. They can be tuned to maximize gain or selectivity per your requirements and their support is outstanding. http://www.simrex.com/site/products/special.htm PRESELECTOR PREAMPLIFER Low cost solution to interference, intermodulation and desensitization problems. Helical Resonator Design. Preselector Specifications (pdf 63k) Preselector Example Diagram (pdf 10k)
Re: [Repeater-Builder] Re: Simrex - GLB Pre-Selector Pre-Amplifier
On Jul 30, 2010, at 9:31 AM, n...@no6b.com wrote: At 7/29/2010 14:59, you wrote: Re: Simrex - GLB Pre-Selector Pre-Amplifier The Simrex (aka GLB) units are actually amplified pre-selector assemblies, not just plain wide-band Receive Pre-Amplifiers. There's a reason why these units offer/spec 8dB Gain versus the others un-protected preamps. The less obvious gain when compared to traditional GasFet and BiPolar RF Preamplifiers is due to the internal integrated pre and post filtering. What does it all mean... If you have some types of IMD grunge problems when trying a regular GasFet/BiPolar Preamplifier, chances are your results using the Simrex/GLB pre-selector might be better. The pre and post filtering inside the Pre-Selector is a big deal. Yes, but the NF is unpublished unknown. I therefore assume it's poor, maybe 3 dB? A Chip Angle GaAsFET @ UHF has 0.5 dB NF. Put a 1/4 wave pass cavity with 0.5 dB loops in front of it you have a narrow 1 dB NF front-end. I'll take 1 dB NF over 3 dB NF any day. The Simrex unit makes a nice solution if you don't have the physical space for a 1/4 wave bottle. Then again, I know someone who just ordered an even smaller MtronPTI front-end crystal filter to solve a front-end overload problem from a TX over 1 MHz away from his RX. Not the best solution (higher loss, can't be retuned if he ever has to change freq.), but I guess it works for him. Bob NO6B If you picked the UHF Simrex unit with less gain, more selectivity than the standard model, then the noise factor should be better? I guess it comes back to price too, a 1/4 wave can plus pre-amp will cost more money... No such thing as a free lunch :-) 73, Jack VK4JRC
Re: [Repeater-Builder] Re: Motorola R-2200A User Manual
Robert, I have a user manual for my R-2200B, not sure of the similarities between the 2 models? Cheers, Jack VK4JRC Sent from my Apple iPad Tablet PC On Jul 26, 2010, at 12:32 PM, Robert kd4...@juno.com wrote: Thanks for the reply Eric, I have the Maintenance Manual. Did they make a How To type of manual? I know a little bit, but really not sure how to navigate around it. Anyone? Robert KD4YDC --- In Repeater-Builder@yahoogroups.com, Eric Lemmon wb6...@... wrote: Robert, I have good news and bad news. The bad news is that the R2200-series Operator's Manual 6881069A79 is out of print and is NLA. The good news is that the R2200A Maintenance Manual 6991069A76 is still available from Motorola Parts, for about $58. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Robert Sent: Sunday, July 25, 2010 5:25 AM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Motorola R-2200A User Manual Does anyone have a link to this? Would love it if this was in pdf as well ;-) 73, Robert KD4YDC
Re: [Repeater-Builder] Re: Hamtronics Repeater Boards?
Thanks for the info, had a look at the HiProrepeaters WEB site but no manuals etc for the Tx/Rx PCBs, might have to follow that up. I have already ordered 2 diplexers, one from here in Australia, the other from China. Fiddling with them will be an interesting exercise :-) Radios ordered so far are Hamtronics PCBs, 2 Vertex Commercial Transceivers with back to back interface. Have a COR/ID kit coming (Electronic Gadgets) My plan is to build a totally field portable, low power (10w or less) 70cm repeater for limited coverage area use. Test all the bits and compare performance etc. If nothing else, it will be a load of fun! Cheers, Jack. Sent from my Apple iPad Tablet PC On Jul 10, 2010, at 2:58 AM, skipp025 skipp...@yahoo.com wrote: vk4jrc ra...@... wrote: I have ordered some Hamtronics UHF Tx Rx PCBs to use for building a repeater. I'm a big fan of using Hamtronics Products... yes, there are often lower cost surplus commercial radio choices for a more complete end result. Those who demonstrate patience, which took me decades to get a decent handle about applying to myself end up with a very satisfying end result. http://groups.yahoo.com/group/Repeater-Builder/photos/album/1157128983/pic/list Not to mention the wondeful hands-on experience and exposure you receive actually building things. Are there any other suppliers who make a similar product that I could buy and make a comparison for performance? Or, should I just stick with the Hamtronics boards, alone? Sure, Maggiore Electronic Lab offers similar products, of which I'm also an owner and fan of... http://www.hiprorepeaters.com/ Cheers, Jack. VK4JRC Good luck with your project Jack, post pictures of the results when you're done. cheers, s.
Re: [Repeater-Builder] Ruggedised panel antennas
Try the Polar Electronics Sector Coverage Panel Antenna model 375A. At 10dBd it a little short on gain but. Web site www.polarelectronics.com.au Cheers, Jack. VK4JRC Sent from my Apple iPad Tablet PC On Jul 7, 2010, at 3:24 PM, Gareth Bennett gare...@es.co.nz wrote: Hi Group, I'm just wondering if anybody has an alternative to Katherin-Scala for heavy duty radomed panel antennas in the 450-500 MHz band at around 10dBi gain that will stand up to the abuse of an alpine site (2Km ASL) Just after feedback and opinions Cheers Gareth Bennett RadioSystems Limited P.O. Box 5202 Dunedin 9024 New Zealand DDI: (03) 489 1101 FAX: (03) 489 1151 MOB: (0224) 588 377 gare...@radsys.co.nz - Original Message - From: Oz-in-DFW To: Repeater-Builder@yahoogroups.com Sent: Wednesday, July 07, 2010 10:07 AM Subject: Re: [Repeater-Builder] Proto boards Or: http://www.wa5vjb.com/products4.html 6.5 by 4.25 Large Proto Board $5 3.75 by 2.75 Small Proto Board $3 Kent is also a source of economical built-to-spec preamps. -- mailto:o...@ozindfw.net Oz POB 93167 Southlake, TX 76092 (Near DFW Airport)
Re: [Repeater-Builder] Ruggedised panel antennas
Ahem..senior moment!! Sent from my Apple iPad Tablet PC On Jul 7, 2010, at 10:49 PM, wd8chl wd8...@gmail.com wrote: On 7/7/2010 2:32 AM, Jack Chomley wrote: Try the Polar Electronics Sector Coverage Panel Antenna model 375A. At 10dBd it a little short on gain but. Web site www.polarelectronics.com.au Cheers, Jack. VK4JRC Except that 10 dBd is a little more then 2db gain over the 10 dBi he spec'd! On Jul 7, 2010, at 3:24 PM, Gareth Bennettgare...@es.co.nz wrote: Hi Group, I'm just wondering if anybody has an alternative to Katherin-Scala for heavy duty radomed panel antennas in the 450-500 MHz band at around 10dBi gain that will stand up to the abuse of an alpine site (2Km ASL)
