Loose Notes 3/8/15

A smattering of intriguing developments that I've encountered lately: 

• N0AGI (Nagi) has an interesting project in the works: a portable HF rig. As usual, he's documented it meticulously on his blog and in video. Part 1 can be found on his blog, and Part 2 of the project can be found on this video. 

• This weekend, I stumbled across the UHF repeater operated by K0LAV (Paul) on 444.950+ (114.8 PL). I've grown accustomed to being unable to reach most of Paul's repeaters, being quite limited in antenna options here and being on the opposite side of the metro from him. But I was pleasantly surprised to see the .950 come back full-scale using my exterior antenna and 10W. I discussed this development with Paul on the MARA UHF .800 repeater and learned that the repeater's antenna was a respectable 90 feet up, and also that it was cross-band linked to his 33 cm 919.100- machine. So, if you've ever wanted to play with 33 cm operation, the UHF .950 is an excellent means to do that. 

•  With the addition of a new exciter, and a 100W Henry PA, the 223.900- (100.0 PL) "Aggrandizer" repeater has officially moved out of "testing" and into "on-air" status. This effort has only been made possible with the help and advice from the local amateur community, though some elements of that same community have placed significant barriers in its path. Whatever success may come from this project is a testament to the positive and co-operative spirit that still exists here, as well as the vision and drive to experiment found in some quarters. While the site in NE Minneapolis keeps the 223.900 in the "hobby" repeater class, we are exploring various linking options to make this repeater more valuable to the amateur radio community.  And, as I predicted back in September, The Aggrandizer is in full operation before the TCRC has restored their 224.540- repeater.

•  In an on-air conversation with N0BVE (Don) yesterday (3/7) I found out that the VHF SNP 145.230- (114.8 PL) repeater that he's running is currently located in Chaska. It comes back to me with a (somewhat noisy) S6 signal, but pretty much everyone in town has a better antenna arrangement than I do, so you can probably reach it much better than me. The .230 is EchoLink-capable (through KA0KMJ-L), though not connected to the rest of the HandiHam network. 

• Per K0LAV (Paul), the 146.850- (no PL) operated by MARA is averaging 9.5 hours of key-up time per day. That figure didn't mean much to me, until Paul explained that it's about twice the activity of just two years ago. No similar records are kept for MARA's UHF counterpart, the 444.800+ (114.8 PL), though it seems to me that activity has increased somewhat over the past year. Certainly, there are more people monitoring it regularly, based on the number of people coming back to me when I throw out my sign there. Maybe UHF is slowly becoming more accepted by the two-metre crowd here.  

Loose Notes 3/1/15

As usual, there are a few things going on deserving of mention. 

• One of the big APRS gateways in town has been missing from the VHF propagation maps for a few days now. N0AGI had some brief down time for a software update, but when it returned to service it was no longer showing up on the propagation maps. This is lousy for the local area, as it deprives metro hams of VHF data. A tweet to the operator of the great propagation site, NG0E (Jon), resolved things quickly.

  

  N0AGI gateway is back on the map

• Rumours are that N0BVE (Don) has plans for a UHF C4FM (System Fusion) repeater on the 444.100+ pair. With the TCFMC's "dot one" going off air for weeks now, it may be that Don has made some kind of arrangement with the (financially-struggling) club that the frequency pair is currently allocated to. No word on the site, potential linking arrangements, or target dates for the new repeater. This could be exciting. EDIT: On-air conversations have clarified things a bit. Don has simply changed the frequency of the C4FM .925 over to the 444.100+ pair, in a gracious effort to help out the TCFMC. At the moment, there is no 442.925+ repeater in operation -- either linked to HandiHam or stand-alone. No word on how long this arrangement will be maintained.

• The 1.25M 223.900- (PL 100.0) "Aggrandizer" repeater has it's new 80W PA installed, and a replacement TH-9000D for the exciter is on its way. KE0NA (Dave) put his own mobile rig into the mix as a temporary exciter for testing purposes. Yesterday (2/28) Dave and I made some tests, but the results weren't that great. Using my exterior ground-plane, the repeater came back as only S3 or S4 with a lot of noise. Switching to my Yagi brought it up to S6 or S7, but doing that before we were using a PA gave me a full-scale signal. Dave checked the output power with his Bird metre, and confirmed 80W going to the antenna. Nothing has really changed on my end, but I'll go over my entire setup today with a fine-tooth comb. I confirmed that I can easily reach other repeaters on the band, though. If you have a 1.25M rig, maybe give the .900 a listen and provide us with some independent data. In the interim, Dave added an LED light bar to the repeater: 

  

  The Aggrandizer is all lit up

• I've been informed that K0LAV (Paul) now has his 147.390+ (94.8 PL) repeater in low-power testing. I'm not able to reach it, so I can't confirm this.

• N0AGI (Nagi) has  new YouTube videos up documenting the setup of his new 442.175+ (100.0 PL) System Fusion repeater. As usual, he goes into painstaking detail, and includes the setup of his WIRES-X node.

Loose Notes 2/22/15

As usual, just a few scattered bits of info that don't merit an in-depth examination. 

• N0BVE (Don) has apparently been trying to get his SNP 2M repeater to take off. On 145.230- (114.8 PL), it's operating out of either Minnetonka or Chaska. It's hard to keep up with the constantly-shifting status of his multiple machines, after all. The EchoLink node says Chaska, but Don has told me that it's at his home in Minnetonka. The 145.23 has a decent signal strength (S7 here in Plymouth), but there's a fair amount of noise. I'm not sure if the audio is just fairly low, or if there's interference, but the quality of the signal is not good relative to the signal strength. There's not a lot of local activity on the repeater, and it's not often linked to the rest of the network, but Don does frequently connect it to a different EchoLink conference -- MN_CONF. This is a chatty (and friendly) group of people from outside of the area, and the connection to the conference server does create activity on a repeater that would otherwise be dead. It's worth checking out.

• One of Don's other projects, the C4FM repeater on 442.925+ (114.8 PL), is still holding up. There's been issues with the PA blowing on the local C4FM repeaters, but this one is working fine. It has a much better signal than the 145.23 machine (from my vantage point, anyway), though it doesn't seem to be connected to the larger HandiHam network. I'm pretty sure that it has WIRES-X access, though, so it's a bit more than a stand-alone UHF machine. 

• It's not often that we can look forward to a new two-metre repeater in town. The frequency pairs are tightly locked up, but K0LAV (Paul) managed to get his hands on the 147.390+ (94.8 PL) pair a few months ago. In an on-air conversation with him, I learned that his two remote receive sites (White Bear Lake and Columbia Heights) are up and running. The repeater itself is not yet on the air, though. Current plans involve a cross-band link to his 1.25M 224.100- (no PL) repeater in Gem Lake, and DTMF access to the SuperLink network. Big plans, certainly, but Paul has a proven track record of making big plans a reality. It's also encouraging to see something innovative finally taking shape on the local 2M scene. The vast majority of those who cling to the two-metre pairs have rejected, struggled, and fumbled with anything new. Adding voice ID seems to be the major concession to the world of thirty years ago. And there's those three D-Star repeaters. And a bare few EchoLink nodes -- that never seem to be logged in. So it's pretty impressive that Paul has undertaken this novel course of action. 

• The major digipeater in the metro, K0YTH-13, has been down for the past three days. I notified N0ZRD (Gordy), and he's confident that it can be returned to service quickly. This is why it's great that we have redundancies in coverage. Most of that redundancy is provided by individuals, and not the clubs. The clubs talk up EmComm, but seem completely incapable of connecting a BaoFeng to a junky old laptop and making even a feeble pretence of  supporting the local APRS infrastructure. Thanks go out to those guys that are there when things fail. 

• I've confirmed that KA0KMJ (John) has his C4FM repeater back on the air in Osseo. Operating in hybrid mode on 444.725+ (127.3 PL), John has reduced his output power to 20W in order to prevent the PA from melting down again. I'm only about seven miles from the repeater, and it comes back S9++ (full scale), but I'll have to try out the coverage on my mobile to get an idea of how useful the machine will be for my day-to-day purposes. The 444.725 holds up the NW for UHF C4FM, while Don's 442.925 repeater takes care of the SW metro. And, of course, K9EQ (Chris) runs his power-house (100W+) 444.525+ (114.8 PL) machine out of Mounds View, which takes care of Minneapolis and St. Paul proper (at least). UHF is definitely where the new stuff happens around here. 

• In about a week, the 1.25M Aggrandizer repeater on 223.900- (100.0 PL) will have its new PA up and running. Capable of 100W, it will be run at "only" 80W to provide a margin of safety and reliability. KE0NA (Dave) has run some models, and we expect that it will cover Minneapolis and most of the first-ring suburbs quite well. The rest of the metro generally falls into a S5-or-less zone. Options for expanding this range (which is already far more than we originally anticipated) are being explored. You can get a full-powered rig for this band for $150, and there's decent mobile coverage for most of the metro already. In a few months, the HandiHam network will be linked to 1.25M and the SuperLink will be accessible. There's already EchoLink on the 224.660- (100.0 PL) repeater. N0FKM (Dan) is pondering the restoration of UHF cross-band with his 224.500- (100.0 PL) machine, too. Things are happening on the infrastructure end, but we need more operators using this band or we'll lose it to commercial interests.

Cheap 1.25M option: BaoFeng UV-82X

Getting on the 1.25M isn't as easy as 2M or UHF, as the options for a rig are limited. For a full-powered rig, the TYT TH-9000D still seems to be best option, and various manufacturers make clones of this radio. The Alinco model has the DSub9 connector already installed on the back, ostensibly for packet use. Otherwise, it's the same radio. The TH-9000D is, itself, a clone of an AnyTone rig -- though AnyTone never bothered to make a model for 220 MHz. 

The TH-9000D (1.25M model) is now available domestically for $150 (plus shipping), and from China for $150 (free shipping). My experience with the U.S. distributor (radio-mart.com) is that the guy takes over a week to actually ship your order, so it's not much faster than buying from China. Any problems are only resolved by shipping the radio back to China, so there's little advantage there either.

But maybe $150 is a bit too much of a gamble for a band like 1.25M, and for a monoband radio at that. Then, you have to consider an HT. Wouxun and TYT make dual-band HTs that include 1.25M, though reviews of those radios are mixed. My experience with the TYT UHF/1.25M offering is not positive, as the radio is worthless for UHF, and it's selling for over $90. The Wouxun, at $130, hardly seems worth it.

The cheapest option -- and a reasonably good one -- is the BaoFeng UV-82X. The UV-82 is, by virtually all accounts, superior to the familiar UV-5R. John at miklor.com has written up a comparison of the two. Higher output power, and better TX/RX audio are significant differences over the old UV-5R that so many roll their eyes at. The UV-82 also has two PTT buttons -- one for the "A" band, and another for "B" band. There's also a speaker mic that's compatible with this dual-button arrangement. 

The UV-82X, at $50 (free shipping), seems like a pretty good option. It pushes over 5W on 2M, and the addition of an external antenna would make it an adequate home or mobile option. Certainly, this wouldn't take the place of a full-powered 50W two-metre FM mobile rig. But it would allow you to play with 220 MHz and sample the local repeater coverage, without being isolated from the activity on 2M. And it wouldn't be an expensive gamble, either. 

I use an old UV-5RS in my home office. Though it has lower output power than the UV-82X, I can readably work the Columbia Heights .660 and .500 repeaters, plus the Arden Hills 223.940 machine, using nothing more than an indoor 1/4-wave whip mag-mounted to a metal paint can sitting next to the window -- from out in Plymouth. So, if you doubt that you can do anything on the band with an HT, you'd be wrong. I've also had good luck reaching these repeaters with the same 1/4-wave whip on my car driving around the west metro. If you can improve on these marginal antenna solutions, the extra power afforded by the UV-82X should allow you to do pretty well getting in to the excellent local repeater infrastructure on the band. 

Locally, the repeater situation continues to improve. The 224.660- (100.0 PL) machine has excellent coverage, along with EchoLink access, and plans for cross-band linking. The 224.500- (114.8 PL) repeater isn't quite at the level of the .660, but it's now functional and is improving. The Arden Hills 223.940- (100.0 PL) remains as reliable as ever, and the link to the HandiHam network will be restored in the future. This would allow the HandiHam network to expand its coverage in the north and east, and the 1.25M band could be one of the best ways to get in for a lot of people that struggle with the VHF .450 coverage. 

There are other repeaters that show potential, as well. The 223.900- (100.0 PL) still requires higher power and better antennae to access, but no one involved in that project is content with that situation. There are plans to add a 70W PA to improve range, and potential linking schemes are being considered. Likewise, the 224.940- (100.0 PL) is searching for a better site that could allow it to become one of the "big boys" on the band. 

Right now, it's going to take a sustained effort to build up a core group of operators on the local 1.25M scene, and some kind of cross-band option on one of the local machines so that those who jump in on the ground floor aren't isolated from the rest of the amateur radio community.

Loose Notes 12/13/14

A few scattered observations this weekend:

• A tip of the hat to KA0KMJ (John), an MGRC member, for letting me know that their Maple Plain 147.000+ (no PL) repeater actually has tone squelch implemented. Now I don't have to hear all of the intermod when I go into Minneapolis and want to use the Maple Plain machine. John further explained that the decision to go without an input PL tone was made to accommodate operators in the area with old two-metre rigs that can't "do" CTCSS. Also, per John, the Robbinsdale UHF 444.775+ (114.8 PL) is sponsored by the MGRC (though the listing says otherwise), and the marginal 443.700+ machine in Maple Grove is not the Club's only foray into UHF.

•  I had a brief chat on that same 147.000+ repeater this afternoon with a mobile ham (callsign mangled). He was heading down to Texas, and had a 5W Yaesu HT and a mag-mount antenna on the van. I found it ironic that he told me that he couldn't get into the Maple Plain machine from his home in Howard Lake, but that he was reaching the repeater from near Northfield while mobile talking to me. The 147.000 seems to have really good "ears". I also had a long conversation with WA0ZDE (Rick) shortly after that using my 9W Leixen with an indoor mag-mount antenna on the opposite side of the building from Maple Plain. I've always liked the 147.000, though activity is definitely low.

•  KE0NA (Dave) is working on The Aggrandizer 223.900- (100.0 PL) repeater today, adding a receive pre-amp. The repeater transmits with okay coverage out to Plymouth, but doesn't hear people trying to get into it well enough for mobile use yet. Give the upgraded machine a try.  

• I had a long chat with N0GOI (Terry) last night on the 444.050+ (114.8 PL) machine. Work is nearly complete on the VHF and UHF repeaters in Foreston, and they are both on the air. Terry always has some exciting plans, and it's interesting to talk to him. The two Foreston machines will be linked (cross-band), but this link will have the ability to be disabled for SkyWarn -- with the UHF machine handling the normal local traffic. UHF is a "tough sell" in the rural areas, but cross-band operation will allow those willing to try it out the chance to still keep in contact with the VHF users. There are also some potential plans to implement the Raspberry Pi RF link boards that N0YNT (Matt) and N0BFG (Ryan) are currently experimenting with. That's "down the road", of course, and the controllers still need to be upgraded or modified to work with the linking scheme. 

• Terry also told me that the UHF 443.575+ (114.8 PL) repeater in NE Minneapolis -- operated by KD0WIL (Eric) -- has been upgraded to a 60W MSF-5000. It took 15W to "ker-chunk" the .575 from here in Plymouth, but it came back with an S7 signal once I got in. This is a repeater operating out of Eric's house in Northeast, so reaching Plymouth is pretty good. At some point, I understand that it will be linked into the MAGIC system to boost their eastern UHF coverage. Eric is also trying to implement EchoLink on the repeater, but no word on what his near-term objective is for a link. 

•  It turns out the 224.500- (114.8 PL) repeater just needed a re-tuning of the duplexer to get into working shape, per N0FKM (Dan). The machine isn't up to Dan's standards yet, but once it is, he'll be exploring cross-band links to at least one of his other (five) repeaters.

• With the ten-metre contest going this weekend, I tried the webSDR receiver in Louisiana for a listen on the 'action'. Though this receiver is primarily for the propagation beacon sub-band, I was quite surprised to find a whole lot of phone activity in the lower section of the band reserved for CW and digital modes. I heard nothing but American phone stations over the course of an hour in this sub-band -- at least the part covered by the webSDR receiver. Wow, that's some HF "elite" we have. Can't even follow the band plan. Any phone contacts made below 28.300 on the band should be disqualified for the purposes of the contest. Why would anyone even try digital modes with these bozos stomping all over the sub-band? I guess that contesters really are better operators than the rest of us.
   

Loose notes 10/22/14

 I guess that I now need to delete this post, too. Not sure how Big Experts on Reddit can "read" a Desperate Cry for Help in this post, but that's why they are so 'smart', I guess. If it continues past this month, I'll take it down. Can't have nothin' nice... 

The Aggrandizer moves into viability

 As I mentioned previously, I'm tangentially involved in an effort to put up an innovative 1.25M repeater here in the metro. The majority of the effort has come from KE0NA (Dave), with considerable help and advice from N0YNT (Matt). Originally, the repeater was planned to take the place of the failed TCRC 224.540- machine in Burnsville, as it had a duplexer, antenna, and site sitting unused. With Dave being the Vice-President of the TCRC, it seemed to be a "done deal", and the TCRC would be the test bed for an innovative concept -- which is kind of what radio clubs are supposed to do.

 No such luck, however. The President of the TCRC, WB0JMG (Artie), unilaterally decreed not only that the repeater we designed would not be put into service on any TCRC site, but he also strictly forbade any club "resources" to be used in the effort -- such as advice or technical help. 

Surely this innovative repeater design must be some kind of dangerous and crazy scheme, right? The wisest course would be to deny the amateur community the use of of one of the few 1.25M repeaters for months on end, rather than take the outrageous risk of even testing this concept, which is clearly doomed to failure and disgrace. Right? That's the only reasonable explanation. 

So, what is this wild and uproariously laughable idea that must be put down and unceremoniously buried? 

It's simply this: put two TYT TH-9000 mobile 1.25M transceivers back to back, with a controller mediating. 

Gear for the 222 MHz band is hard to come by. There aren't a lot of old commercial repeaters sitting around (as is the case with 2M and 70cm) to press into service and use in amateur radio. The TH-9000 is uniquely designed to be used as a repeater, with an internal header that provides TX and RX audio, COS, PTT, and +5 vDC. It only has about 45W RF output, but it can certainly drive a PA. Even at 45W, the metro area could be fairly well covered, especially with a good site and antenna. 

Since this is different from how repeaters are normally operated, there was no shortage of "experts" dismissing the idea out-of-hand. We can't be 'experimenting', after all. This is amateur radio! There are no new ideas; only bad ones that experts laugh at. 

Undeterred, we went ahead with the project. Barred from using any TCRC expertise, Matt set up a controller. Matt is a member of the TCRC (as am I), but we are not part of the club's "Tech Team", and so we considered ourselves unbound by the President's decree. The repeater, now named "The Aggrandizer", was field tested at the July AITP event. It didn't "de-sense", and worked an HT from about a mile away. Moving forward from that point, I prevailed upon K0LAV (Paul) and K9EQ (Chris) for advice, and Dave consulted with KA0KMJ (John), as these were hams free of any restrictions placed on them by the TCRC. 

As it now stands, Dave has set up a transmitting antenna at his home in NE Minneapolis for The Aggrandizer. He got it provisionally co-ordinated for 224.240-, which is the 1.25M SNP pair. As he mastered the mysteries of the controller, he set up a voice ID to "beacon" every ten minutes. The next step is the installation of a receiving antenna, which is challenging because he doesn't have a duplexer. Like everything else on 1.25M, duplexers are quite scarce.

KA0KMJ confirmed last week the the signal was reaching his home in Osseo. I also drove around Crystal, New Hope, Plymouth, and Golden Valley listening to the beacon on my Kenwood F6-A. The antenna at Dave's is only about 25 feet up, and in an area that isn't particularly elevated, but I received the signal at S9 in most places on my drive. There were some low spots at only S2, but that's to be expected with a "compromise" site. 

The propagation characteristics of the 222 MHz band are pretty favourable for amateur use. It has coverage beyond "line of sight" like VHF, but it still has some ability to reflect off objects like UHF. Ideally, 1.25M is a better choice for urban and suburban amateur radio than 2M is, but 2M got a huge advantage in the early goings from the availability of VHF commercial gear. 

At some point, this project will produce a working 1.25M repeater. It will probably happen before the TCRC gets the .540 back on the air. If the TCRC would relent, it could be on the air immediately, and I would happily provide a 100W PA to make it the best 1.25M repeater in the State. They have a duplexer and antenna on a great site that are just sitting unused. 

Let's look at the Mission Statement of the Twin Cities Repeater Club: 

The purpose of the TCRC is to facilitate the local communication needs of its members by owning and operating a state of the art wide area coverage two meter repeater system. The club will further involve itself in secondary activities intended to (1) promote the exchange of ideas and information related to amateur radio, (2) strengthen the fellowship and camaraderie among the members, (3) serve the local amateur radio community, and (4) increase local public safety.

Okay, so it's all about 2M now. Good to know. Maybe we already did. I'm left wondering how an Order of Silence from the President on this project promotes "the exchange of ideas and information related to amateur radio", though. If this concept works, it could make it pretty easy to not only set up 1.25M repeaters in any community, but also UHF repeaters, since there are UHF TH-9000's. We can't allow hams to set up cheap repeaters and learn how duplexers and controllers work, can we? It's all so "experimental", which is what amateur radio is apparently there to prevent. These secrets must be carefully guarded, and only revealed to those that our Wise Elders deem worthy... and in possession of sufficient disposable income. 

I know that KE0NA has described the experience gained from this project as "priceless". It's certainly been an educational experience for me as well, in my limited role. And KD0ZWN (Josh) has been inspired to experiment with Raspberry Pi controllers due to his involvement in this secretive and forbidden project. Even the experienced hams that we asked for advice had to do a little "re-thinking" of the conventional wisdom. 

The Aggrandizer will on display (in all its horror) at the September AITP event next weekend, where another field test will be done. Bring a 222 MHz HT and test it out. 

Dave has documented every step of this effort meticulously. He will be able to produce step-by-step instructions that will enable virtually any ham to replicate this for themselves. This information will be available on this blog. There is documentation to show you how to wire the headers of the TH-9000. There is detailed information on how to connect a controller between the two radios. He explains how to add extra heat sink capability. With sufficient vertical separation between the TX and RX antennae, or with a split site arrangement, you can create your own repeater without a duplexer. Of course, this is all a lot easier on UHF, where there is 5 MHz separating the TX and RX frequencies, and duplexers for the band are plentiful and relatively cheap. And, at the end of day, if you wish to take it all down, you have two new mobile transceivers rather than one ancient repeater. 

It's not just repeaters that are made relatively simple by the accommodations of the TH-9000. APRS digipeaters and gateways are made possible with the VHF model. Auxiliary RF links between repeaters for cross-band functionality or remote receive sites are also likewise simplified with the UHF model. Connections for EchoLink, too, are simplified. You can set up that simplex node that you've thought about. Unlike two metres, there are a whole lot of open frequency pairs on 222 MHz to set up repeaters on, even at the 'hobby' level. Experiment! Set up the first EchoLink-capable 1.25M repeater in the State. Make a cross-band UHF/1.25M repeater happen. Set up 1.25M APRS. Why not have a VHF digipeater at your cabin? It's all possible, and it's all an excellent chance to learn and teach others from your experience.

Behold The Aggrandizer!

As Dave makes progress, your signal reports will be helpful. The beacon isn't always on, but if you hear it on 224.240, it would be nice for us to know. When the receiving antenna goes up, those reports will be even more valuable. If nothing else, check out this innovative repeater at the AITP event. Maybe you will be inspired to join the effort...unless someone orders you not to. 

It's gratifying to me that there are experienced hams out there willing to think "outside the box" and help bring new projects into being. I especially appreciate people like Dave and Matt, who say "Let's make it happen!" instead of smugly explaining "That will never work!". The purveyors of 'conventional wisdom' are many, and they receive a disproportionate amount of respect for merely parroting the worn-out notion that FM is limited to two metres. 

Have we, as a community, become so hidebound and backward-looking that we risk becoming a parody of the visionaries that first established the two-metre infrastructure here in the metro? Are our clubs, which were supposed to leverage the power of their membership into progress, now nothing more than museums and refuges for those obsessed with preserving the past? If so, then the hobby has to look to the few that can still summon the spirit that will move us into the future. 

EDIT: Apparently some people are confused as to the difference between the TCRC and the TCFMC. KE0NA is the VP of the TCRC, not the TCFMC. This post has nothing to with the TCFMC.

EDIT: N0FKM (Dan) has approached N0YNT (Matt) with a potential offer of practical help with this project, possibly teaming up with Dave and Matt to put The Aggrandizer on the air. Dan operates repeaters on three bands in the metro.

1.25M repeater from mobiles

N0YNT (Matt) and KE0NA (Dave) have put together a working repeater from two TYT TH-9000s and a controller. As I explained previously here and here,  the TH-9000 is uniquely set up to accommodate an interface with a controller. After the TCRC's .540 repeater on 1.25M was taken out of service, Matt, Dave and I considered replacing it with a pair of TH-9000s and using the TCRC's antenna and duplexer.

Unfortunately, the TCRC balked at the proposition. Instead of abandoning the concept, though, we moved ahead. My role merely consisted of getting a 1.25M TH-9000D. Dave wired a cable to the radios' interface, added an extra heat sink, and mounted it all on a rack shelf. Matt got a new, advanced, three-port controller. I watched as Matt and Dave connected the controller and worked out the issues last Monday. It was tested with a dummy load and a mag-mount whip, and found to actually function as a repeater. It was nicknamed "The Aggrandizer".

At this point, it's all experimental. There is no confirmed site, nor co-ordinated frequency. But the principle is sound, and has been proven out.

At some point, the documentation will be put together for this project. From that information, it should be relatively easy for someone to duplicate this with VHF or UHF models of the TH-9000D. Simple repeaters could be thrown together fairly cheaply and easily -- even cross-band. Remote receive sites, translators, digipeaters, and temporary field repeaters also become much simpler. And you can always take it apart and use the radios as standard mobile or base radios -- which is something that you can't do with a 'real' repeater.

While an expensive controller was used in this case, there are sub-$100 options out there for a "no frills, no thrills" hobby repeater. A field test has shown that, on 1.25M (1.6MHz offset), there is absolutely no "de-sensing" at 10W output without a duplexer. Higher power levels weren't tested, but 25W could be practical. UHF pairs have a much greater 5 MHz offset, and higher power levels should be practical without suffering the losses associated with a duplexer. The transmitter radio draws only 12A at full power, with the receive radio drawing less than 1A. But full power on the UHF model is 40W, and antenna quality and elevation is more important than raw power on that band.

Since 1.25M equipment is so scarce, this arrangement might be the only acceptable way to set up a 1.25M repeater for some. TH-9000D mobiles are sold for around $150. Sure, you can probably  get an old repeater for the price of two mobiles, but these are brand new with warranty. And you'll have two new FM transceivers, instead of one clunky relic.

This isn't to say that this "mobile repeater" can take the place of any repeater. It's an inexpensive and flexible option, however, requiring little technical expertise.

Behold "The Aggrandizer": two TH-9000s with Arcom controller

Photo courtesy of Chuck Marshall - KD0UIH