[Repeater-Builder] Re: 455khz filter for Mastr II discriminator audio
I checked yesterday and we are getting audio off the Vol/Squelch Hi pin as most people do. We wired it up instead using the RUS signal and a transistor and disabled the smrt squelch in the controller and it's working like a champ! Yesterday myself and a couple other guys lugged this thing up to a building and it's on the air now and running pretty nicely. Thanks for all your suggestions and discussion. I have another problem re: antenna but I'll make another post about that. --- In Repeater-Builder@yahoogroups.com, Nate Duehr [EMAIL PROTECTED] wrote: Willis M. Hagler wrote: I'm not terribly familiar with the nuts bolts (so to speak) of the components so was unsure if the various styles of inductors all did the same thing and I was concerned once I looked and found what appears to be a pretty radical variance in size of available inductors all rated at 10 mH. Understand... the question still remains though -- are you connected to Volume/Squelch Hi coming off the MASTR II? There should be very little 455 KHz component there... I think... but there are other places to tap discriminator audio from... and we don't know from the other end of the keyboard here what your exact setup is... unless I missed that somehow too. (GRIN) Nate WY0X
[Repeater-Builder] antenna suggestions for 440mhz
Hi All, Does anybody have experience running the DB 404/408/420 type antennas down around 440.000mhz transmit? The 'B' version of these antennas is manufactured for 450-470mhz but I know they operate nicely just below 450 in the ham band. I have a repeater running now with a Diamond X-510 antenna and the signal flutters a bit when the Diamond flops around in the wind so I'm looking into a stiffer, non-fiberglass antenna. I like the DB's but unsure how bad the 450mhz matches when trying to use it down at 440.000mhz. Any other suggestions for a omni UHF antenna that will play well in the low end of the 440 repeater band with 10-12db gain? Thanks, Mark Hagler W7WMH Seattle
[Repeater-Builder] Re: 455khz filter for Mastr II discriminator audio
Whoa, where did we get off on voters? I asked the question originally based on a conversation I had with Pacific Research. I'm using their RI-300e controller which has been a solid controller for me on several other repeaters, but I've never tried to interface to a Mastr II. With the particular combination of a Mastr II and the RI-300e smart squelch setup I find the squelch action is not working well at all. I spoke with Greg (Gregg?) on the phone and he said they have had trouble with 455khz coming out of the receiver and throwing off the smart squelch. Their manual also mentions this: http://www.pacres.com/support/manuals/ri-300%20user%20manual%20v3_11.pdf On printed page 12 (pdf page 20) it says If your discriminator does not have adequate filtering for 455 kHz, you will have to provide for this filtering between the radio and controller. A 10mH inductor in line with a 1000pF capacitor to ground should work. You may need to adjust these values according to the output impedance of your discriminator. So I was proceeding down the path of a 10 mH inductor, and the feedback I really wanted from this group is what to do about this inductor as I see I can buy either a through-the-hole board mounted one that appears to look somewhat like a capacitor, or I can get a bunch of windings on a torroid core and make a choke. I'm pretty new at this so was asking more for advice along these lines. However, it's also very useful to know that the GE Mastr II UHF receiver shouldn't be outputting 455khz at all so I'm still not sure what the problem is. Thanks all, Mark Hagler W7WMH Seattle --- In Repeater-Builder@yahoogroups.com, Nate Duehr [EMAIL PROTECTED] wrote: Yeah, understood... but this is a voter, and they're usually designed to pick off at the discriminator, which can be just about anything. It would seem that even if you didn't filter right at the entrance to the voter, you'd want your squelch circuit to ONLY look at certain frequencies and you'd design accordingly. I totally understand what you're saying, I just think with a voter, it's a different thing than a controller. Nate WY0X
[Repeater-Builder] Re: 455khz filter for Mastr II discriminator audio
Thank you Nate, this is getting mainly to what I wanted to know (and am still interested to know) though. I'm already finished wiring up this controller using the RUS line + a NPN transistor to drive the CAS input on the controller for this particular project. At any rate the education about the inductors is still useful knowledge. I'm not terribly familiar with the nuts bolts (so to speak) of the components so was unsure if the various styles of inductors all did the same thing and I was concerned once I looked and found what appears to be a pretty radical variance in size of available inductors all rated at 10 mH. Thanks Mark Hagler --- In Repeater-Builder@yahoogroups.com, Nate Duehr [EMAIL PROTECTED] wrote: As far as the physical mounting properties of the inductor, that all depends on whether you're going to try to place the inductor/capacitor combo somewhere in the controller, somewhere in the MASTR II, or in its own box or similar. Nate WY0X
[Repeater-Builder] Re: 455khz filter for Mastr II discriminator audio
Hi Guys, Well, I don't have many answers for you. I am new in this field and trying to learn and am sharing what I have heard from others who claim to have had this problem with a Mastr II. The gentleman at Pacific Research who manufactures the controller has write up on this in their manual but since I'm not the expert here I'm unable to tell if it's not applicable to the Mastr II without asking the question. I'll put it on the analyzer again and look but I'm pretty sure there's a pronounced spike in the discriminator output up around 450khz. There is, without a doubt, some unexpected high frequency noise on the discriminator audio there that's throwing off the offboard squelch. In the mean time I've wired up the Mastr II's RUS output with a 10k resistor and a 2N transistor to provide a open collector output to drive the controller with external squelch and this is working quite nicely. Sorry for any confusion, I'm just going to give up on the digital squelch. Thanks, Mark Hagler W7WMH Seattle --- In Repeater-Builder@yahoogroups.com, Wayne [EMAIL PROTECTED] wrote: Wjhat nobody seems to be pointing out is the simple fact that the Mastr II series does not normally use a 455 KHz IF frequency. It would have to be a special IFAS board with a second converter to get from the normal 11.2 MHz, or 9.4 MHz in low band and 800 MHz units, plus a very few that have a 10.7 MHz IF frequency. I have one of the latter boards, quite a bit different that the normal IFAS boards. So tell me just how you arrived at 455 KHz? A single conversion receiver using 455 KHz would be super prone to severe image problems. Please cite the exact location showing any Mastr II using a 455 KHz IF frequency? BTW, what schematics have you looked at for the Mastr II RX units? Wayne WA2YNE Mastr II repeater on 441.950TX On Sat, 31 May 2008 15:55:28 -0500, Willis M. Hagler [EMAIL PROTECTED] wrote: Hello Ron, The audio emphasis for FM is a different issue. When I put the discriminator output from the Mastr II receiver on a analyzer you can clearly see a spike way out at 455khz which I believe is the IF frequency in the receiver. This controller has a auto-squelch feature (it does not use a COS/RUS line at all) and it listens for the presence of high-frequency noise coming off of the receiver to control the squelch. When a nice, full quieting FM signal shows up the high frequency noise goes away and the controller will detect this and kick on the transmitter. This detection circuit is behaving poorly on the Mastr II because this strong 455khz component is throwing it off and making it shut down the squelch because it thinks there's a lot of high-frequency noise even when the signal is actually full quieting. Running the audio through a 10 mH inductor tied to a 1000pf cap to ground should cause it to roll off the very high audio frequency and solve the problem but here's what I run into trouble, there's thousands of parts out there that say 10 mH inductor so I'm over my electronics head now! Thanks, Mark Hagler W7WMH Seattle -- Using Opera's revolutionary e-mail client: http://www.opera.com/mail/
[Repeater-Builder] 455khz filter for Mastr II discriminator audio
Hi All, I am trying to build a circuit to roll of the discriminator audio coming out of my UHF Mastr II receiver. I have one of those controllers that does smart squelch by paying attention to the high frequency noise and it seems the Mastr II receiver does not have adequate filtering to stop the 455khz IF frequency. The manufacturer says this is a problem they are aware of with Mastr II's and recommends a 10 mH inductor in line with a 1000 pF cap to ground to get the discriminator audio to roll off far under 455khz. Now, I'm pretty new at this so am not sure exactly what I'm looking for in a 10 mH inductor. I have found locally some high current RF chokes rated at 10 mH inductance, and when I search on Mouser for a 10 mH inductor it returns many thousands of results.The cheapest thing I can find on Mouser is a tiny through-the-hole component to mount on a board and has a small current rating, but I suspect this would be fine for this purpose. Has anybody out there built such a filter to handle the 455khz IF frequency in the Mastr II receiver before, and could you recommend more specifically what kind of 10 mH inductor I'm looking for? Thanks much Mark Hagler W7WMH Seattle
[Repeater-Builder] Re: 455khz filter for Mastr II discriminator audio
Hello Ron, The audio emphasis for FM is a different issue. When I put the discriminator output from the Mastr II receiver on a analyzer you can clearly see a spike way out at 455khz which I believe is the IF frequency in the receiver. This controller has a auto-squelch feature (it does not use a COS/RUS line at all) and it listens for the presence of high-frequency noise coming off of the receiver to control the squelch. When a nice, full quieting FM signal shows up the high frequency noise goes away and the controller will detect this and kick on the transmitter. This detection circuit is behaving poorly on the Mastr II because this strong 455khz component is throwing it off and making it shut down the squelch because it thinks there's a lot of high-frequency noise even when the signal is actually full quieting. Running the audio through a 10 mH inductor tied to a 1000pf cap to ground should cause it to roll off the very high audio frequency and solve the problem but here's what I run into trouble, there's thousands of parts out there that say 10 mH inductor so I'm over my electronics head now! Thanks, Mark Hagler W7WMH Seattle --- In Repeater-Builder@yahoogroups.com, Ron Wright [EMAIL PROTECTED] wrote: Mark, Not sure what the manufacture is talking about. I think your problem is at the audio level, not 455 kHz. Sounds as if you are taking de-emphasised audio which has a roll up of 6 db/octive...with same deviation coming in as you double the mod freq you double the amplitude. This give tenny auido, lots of highs. It is what comes out of the MII discrementator. You need a 6 db/octive circuit to compensate for this. Try this circuit: http://www.n1uec.org/n1uec/deemphasis.html I've used similar (.01 cap instead of .0068 and a few other component differences). You will see a world of difference. 73, ron, n9ee/r
[Repeater-Builder] GE Mastr II Station battery backup question
Hello All, I have acquired a UHF Mastr II station in great working order. It's got what appears to be a 65-watt mobile type PA (approx 2 high heatsink that sticks out the back) so someday I'd like to upgrade that to a continuous duty model when I run across one. In the mean time I am wondering how to adapt a battery backup system into this unit. I've got the original 30 amp (I think) GE power supply, where the station gets power from the classic Molex-style connector and the PA gets power through the large fuse on the rear of the unit. What I don't see anywhere back there is any designated place to hook up a battery circuit. I'm pretty sure there are hundreds of these things across the country in amateur service and undoubtedly many of you have made some battery system for this very same setup. If anybody could share how you've worked in a battery backup and some sort of charging system I'd love to hear about it. Thanks all!! Mark Hagler W7WMH Seattle
[Repeater-Builder] Re: GE Mastr II Station battery backup question
Hello Jim Thank you for the information. If my GE power supply had the modification installed with a relay to switch to battery power then I would assume there would be some sort of battery terminals on the power supply. Mine doesn't have anything that looks like that so I'm guessing the power supply I have was not built with that mod. Do you (or anybody else) know if it's possible to modify the power supply to add these parts or if anything like this has been done before? Also I am considering not using the GE power supply at all and using a newer one with battery service built in. This is assuming that the GE Master II will run fine off of a regular 13.8v power supply rated for sufficient continuous duty current. If anybody has experience along these lines I'd be interested in hearing about what you've done for power supply that isn't the original GE one. Thanks all, this is a great group of people and I enjoy reading this list! Mark Hagler W7WMH Seattle --- In Repeater-Builder@yahoogroups.com, Jim Brown [EMAIL PROTECTED] wrote: Willis, I have run across two different versions of a factory mod to apply a backup battery to a Mastr II. One has a built in charger and the other uses an external charger. The stock GE power supply has a bleeder resistor across the output to keep the voltage in check when lightly loaded, and that has to be disconnected in battery service. The relay in the power supply changes the source over to the battery when the AC power fails and disconnect the bleeder at the same time. It would quickly discharge the battery if it were left connected. The filter caps are still in the circuit when the battery is engaged, so there will be no interruption of service when the AC fails. Not even a glitch on the transmitter if it happened to be keyed. Here is a link to a recent backup system I installed on a GE Mastr II repeater. It did not have the built in charger, so an outboard charger is used. http://sbarcnm.org/forum/index.php?topic=102.0 73 - Jim W5ZIT Willis M. Hagler [EMAIL PROTECTED] wrote: Hello All, I have acquired a UHF Mastr II station in great working order. It's got what appears to be a 65-watt mobile type PA (approx 2 high heatsink that sticks out the back) so someday I'd like to upgrade that to a continuous duty model when I run across one. In the mean time I am wondering how to adapt a battery backup system into this unit. I've got the original 30 amp (I think) GE power supply, where the station gets power from the classic Molex-style connector and the PA gets power through the large fuse on the rear of the unit. What I don't see anywhere back there is any designated place to hook up a battery circuit. I'm pretty sure there are hundreds of these things across the country in amateur service and undoubtedly many of you have made some battery system for this very same setup. If anybody could share how you've worked in a battery backup and some sort of charging system I'd love to hear about it. Thanks all!! Mark Hagler W7WMH Seattle
[Repeater-Builder] WTB: GE MastrII ICOM's
Hello everyone, I would like to buy a set of ICOM's for a MastrII repeater. We have one set now but would prefer not to lose those as they are already set on a useful frequency pair. So, I am trying to find a vendor that will sell me the whole ICOM (not just a crystal) which I can then have re-crystaled to the other frequency. If anybody has a pair of ICOM's to sell or any recommendations on a vendor who sells them I would be glad to hear about it. Thanks much, Mark Hagler W7WMH Seattle
[Repeater-Builder] feedline advice
Hello All, I am putting up a UHF repeater in Seattle and have a question regarding feedline losses.The repeater site is on top of a building and the distance from where the repeater/duplexer will be located is less than 25 feet of coax distance away from the antenna mount. Of course I would like to reduce the system losses as much as possible so I'm willing to pay for ~25 feet of 7/8 Heliax. However my question is more about the loss experienced with inter-series connectors in the feedline. The 7/8 Heliax is not very friendly to bend and route into the cabinet for direct connection to the duplexer, so every repeater I've seen has a short chunk of something more friendly like RG-214 going from the duplexer, through the cabinet, and then joins to the Heliax with some kind of N-male/N-male adapter. What kind of signal loss occurs through such an adapter at 442mhz? On such a short run am I losing more signal through a Male/Male adapter, such that I just may be better off running a single segment of RG-214 the entire 25 feet? As far as I can tell, 25 feet of RG-214 would be about 1.28 dB of loss, while 25 feet of LDF5-50a Heliax would be as low as 0.2 dB, but if a single Male/Male adapter causes anything close to 1 dB of loss than it seems like a wash to me... Thanks for any advice. 73 and Merry Christmas to everyone. Mark Hagler W7WMH Seattle
[Repeater-Builder] power supply / battery system for repeater site
Hello Everyone, I am wondering what repeater operators commonly use when a 12v power supply as well as a battery charging and switching system is needed at a repeater site. My repeater has an internal 120v power transformer that feeds a 12v regulator box, and also has a battery circuit on the back of the repeater that will allow it to draw from batteries when the main power is lost. It supplies a very low current trickle to keep the batteries charged up, however if the batteries drain due to extended power outage it does not provide any sort of reasonable facility to charge them back up again. The manufacturer recommends to take the batteries off, charge them externally, and then return them to float charge... however that's not very feasible if the repeater is located on a mountain or some other location that's not easily accessible on short notice. I'm thinking of just ditching the internal power supply and building a more robust off-board power supply and battery charging system that can switch onto the batteries and charge them up again when the main power returns. For use at home I like the PWRGate units which maintain the batteries nicely but I am wondering if others have used those at repeater sites with no trouble? Thanks anybody who has information to provide. This group is a wonderful resource for all things repeater-related. Yours, Mark Hagler W7WMH Seattle
[Repeater-Builder] looking for Pacific Research RI-310
Hello Amateurs, I am looking high and low for anybody who has an older Pacific Research RI-310 controller they aren't using. We have a Vertex VXR-5000 repeater in need of a controller and the RI-310 was a custom-fit plug play for this repeater. Unfortunately Pacific Research discontinued the product when Vertex stopped selling the VXR-5000. If anybody has a RI-310 or knows of somebody with one I would be very pleased to discuss buying it. Also if you have a RI-310 installed in a functional UHF VXR-5000 I would also consider buying the whole unit as I'd also like to acquire a spare repeater chassis. Thanks all, Mark Hagler W7WMH Seattle, WA
