X-Band repeater project

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ramal121

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So myself and a few other hams volunteer each year to lend a hand to a local motorcycle club that holds their enduro to raise funds for their club. Great fun and good operational experience. Runs two days as the second day is a smaller family event.

Anyway, we have use of a local 2 meter repeater at our disposal that covers a majority of the course very well. The only poor spot happens to be the area of the start/finish of the race. This is where race admin is, along with medical and law enforcement. Shadows have a hard time keeping up with their assignment and hitting the repeater with a hand-held.

This year we will try a cross-band repeater configuration where all members in the hole will use UHF to bounce back to the VHF repeater. This is what I built to try to ease the pain.



The lower section of the weather tight box contains an Alinco DR-635 dual bander. The reason we went with this radio is it very easy to operate and select cross-band repeat, and also it was on close out at HRO (#frugal). The bottom section also has a 20Ah battery and room to store coax and a hardware/tool pouch. The lid has the solar charge controller, a master switch to not only shut off the battery but the PV panel as well as so not to cook the charge controller. Also note a DC timer. Because we will not need to use the repeater at night and the whole thing draws just south of half an amp when on, the timer disconnects the radio between the hours of 9:00pm to 6:00am to conserve battery.



The solar panel (20 watt) and antenna coax are fed through a weather tight receptacle cover at the back of the box. The PV panel can also shield the entrance when propped up against the box if the weather looks inclement.



The antenna mast is a ten foot chunk of EMT. I store the antenna (a Diamond NR77HA) along with the base mount radials in the pipe. A dummy SO-239 with velcro attached keeps the antenna in place inside. Instead of guy lines, I'm using a concrete base kinda like what you'd see for a patio umbrella. The base antenna mount sits nicely with velcro to the lid of the hard case and the hose clamps are in the tool bag.

I intend for this to operate at low power (5 watts) on both bands. Will have to monitor the unit to see how bad the heat build-up gets with the cover closed. If need be, an exhaust fan is not out of the question but I'm trying to keep the penetrations at a minimum for now. The beta test is coming up soon.
 
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K9DAK

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Brilliant!

Can you set up that Alinco so it only X-bands one way... i.e., UHF to VHF? Otherwise you'd have to have a way for it to ID if it transmits on the UHF side.

Again... very well thought out setup... nice job!
 

ramal121

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Brilliant!

Can you set up that Alinco so it only X-bands one way... i.e., UHF to VHF? Otherwise you'd have to have a way for it to ID if it transmits on the UHF side.

Again... very well thought out setup... nice job!
Thanks. No, once you enable x-band repeat on any of these dual banders you only get bidirectional repeat. I guess you could put ctcss/dcs on the receive of one band and not publish it to keep it going one direction, but that's a kludge.

Also any of these dual banders that will x-band repeat do not have any means to ID on either band. Luckily a voice ID is quite ligit. However, where we will deploy this unit, I don't think anyone will give a sacks worth of sour owl crap whether it ID'S correctly or not.

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WA0CBW

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If using bi-directional X-band repeat remember that the repeater carrier has to drop before the X-band repeater can turn around. A "short" tail on the repeater will speed up the turn around time.
BB
 

ke6gcv

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Setup Half-Duplex

Very nice setup! I like that!

I understand the Start/Finish being a bit of a hole. Hence the need for crossband. My question is: Is the repeater reception fairly decent on an HT? In other words, can you hear the repeater on your portable, but just can't reach it?

I'm asking because, if you can hear the repeater on your HTs but can't reach it, it may be in your best interest to setup your crossband to transmit on the repeater input. Then have the volunteers receive the repeater signal on their HTs. Make sense?

Doing this will save the battery power on the crossband, not heat up the radio as fast, and allow a quicker response from the field units because you don't have to wait for the crossband to drop.
 

zz0468

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Am I the only one who saw the name of the thread and immediately thought "cool, a 10 GHz repeater setup"?
There actually is one in the Bay area, and I'm aware of one in planning in southern California. I'm with you on that... I was all excited until I read the OPs post.
 

AK9R

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No, once you enable x-band repeat on any of these dual banders you only get bidirectional repeat....Also any of these dual banders that will x-band repeat do not have any means to ID on either band.
There are some amateur radio dual-band radios that will do one-way cross-band. For example, the Kenwood TM-V71A can be set for what Kenwood calls "locked-band repeat" in that they will only repeat one way. The V71 also has a built-in CW IDer. It's a little rude, but it's there.
 

teufler

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fOR ID'ING, I have used a ht that has ARTS, like a yaesu vx7. Set it for your cross band input, then every 10 minutes it puts out your cw id, that radio is iding as well as the cross band unit that acdepts the ARTS SIGNAL AND since there is no other ARTS in range, it id's too.
 

ke6gcv

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There are some amateur radio dual-band radios that will do one-way cross-band. For example, the Kenwood TM-V71A can be set for what Kenwood calls "locked-band repeat" in that they will only repeat one way. The V71 also has a built-in CW IDer. It's a little rude, but it's there.
I think all mobiles with crossband capability allow for simplex crossband. My FT-8800 does that. I had an Alinco DR-605TQ that did the same thing. I programmed simplex frequencies for crossband. Works like a champ! Can't speak to the ID part for what you're describing, but given that you voice your call sign over the air, I'd say you're in the clear.

As I said before. This is a very nice setup! It's simple and quick to deploy for local, on-scene ops for an event such as the one the OP has mentioned. I like it!
 

ramal121

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Very nice setup! I like that!

I understand the Start/Finish being a bit of a hole. Hence the need for crossband. My question is: Is the repeater reception fairly decent on an HT? In other words, can you hear the repeater on your portable, but just can't reach it?

I'm asking because, if you can hear the repeater on your HTs but can't reach it, it may be in your best interest to setup your crossband to transmit on the repeater input. Then have the volunteers receive the repeater signal on their HTs. Make sense?

Doing this will save the battery power on the crossband, not heat up the radio as fast, and allow a quicker response from the field units because you don't have to wait for the crossband to drop.
That;s an idea. Although the VHF repeater receive is not 100%, it is better than the transmit out to the repeater. I'll get one person to try it out to see how works. I'm all for conserving time, money, lubricants and energy.

Am I the only one who saw the name of the thread and immediately thought "cool, a 10 GHz repeater setup"?!
Sorry for my lazy spelling getting all the nano wave geeks worked up into a froth.
 
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