Building a HAM Repeater with HT's

[AK4GA]

This has got to be a joke.

 

[centuryvrproductions]

Nice, a whole page of laughing at me... im obviously not going to do it i was just getting opinions. but i guess i have it

 

[gewecke]

this i a side project so i am sorry if it is not perfect.. but yes i finally spent some money on a pair of maxtracs.... only 25 Watts but im still experimenting... I am just interested in making a fully functional repeater.

I am thinking about making my own duplexer out of coffie cans but for the work it will be i have no way of tuning it properly... as for the antenna i have a homemade Dipole from Coax cable, it is also not tuned. lots more work to be done and more money to be spent.

.....Save the the coffee cans for your loose change, and use that to buy REAL duplexer cavities! :wink:

73,
n9zas

 

[KC4RAF]

Here's a site with the idea of coffee cans used.

70CM Duplexer.
He gives the material needed and where to buy (if you're in the dark).
His idea has been used by quite of few, even those who laughed at the thought! lol

BTW Century, you've got to be thick skinned sometimes when you share ideas! Also, the Ham radio hobby was raised by those with wacky ideas. There's a lot of good Hams out there, and some who are just arrogant and plain ol' dumb. Experiment and see what you can do. Just remember to be safe around A/C and D/C currents. (yeah I know, double use of current). And always listen to what people have to say. Some times we are right, other times we're wrong, (and hate to admit it!).

 

[gewecke]

70CM Duplexer.
He gives the material needed and where to buy (if you're in the dark).
His idea has been used by quite of few, even those who laughed at the thought! lol

Well...at least they drink great coffee.

73,
n9zas

 

[KC4RAF]

Yes N9ZAS, ANY coffee was good! lol

Just like a Simson 260, or the ol' soldering iron, coffee was mandatory. Now a days I think it's Pepsi or Coke, (ugh ugh, sticking my finder down my throat!! lol)

 

[CalebATC]

Not sure how the range will be, but I know it won't be too far at all!

Good luck, and let us know how it turns out!

 

[benuk]

How did you do it?

I Found it... I took an old transistor circut i made from my squelch tapped scanner and i attatched it to pins 5 and 8. (SPK return) and it triggers a relay... now i am going to buy a repeater controller, duplexors and a 100Watt Power amp...

I am also setting up a couple of HT600E as a simple duplex repeater (no traditional controller, no ID, just rebroadcast everything that opens the squelch on either radio). I would love to know what circuit you made to detect audio on the speaker pins. Also, I'd love to know what I have to do to get the audio level etc safe to feed into the mic input.

 

[centuryvrproductions]

Ur quite right!

This has got to be a joke.

Wow, Going back and reading this..... I can only laugh at my ignorance!

This was a middle school project of mine with large expectations (200Watts! haha). Now that I am a graduate of High School, I have learned much. I can look at the users who were downing me on the project and understand there point lol. For those who said go to a mobile or a desktrac, I have played with bolth and good advice! lol


Now to make this post/thread useful to others;
(as well as repeating most of the usefull advice given from other posts)

Using HTs for a repeater, can be fun to build, easiest way to play with the concept of a repeater and can be very useful if there is a need for a small low power portable repeater.

Go with mobiles, if you lil more serious about a repeater project maybe a mobile duplexer, I have built one, played with it, put lots of time into it, had my fun and had a resonable coverage area.

But a good repeater takes detication, time, $$$$.$$ (A Job) and...some Responsibility. I would say not a project for an average kid.

I haven't given up but have grown into other interests and will hold this idea for another time

 

[techguru]

I've actually been considering building a cross-band repeater out of two Baofeng's and a Mirage amp. Cross-band to avoid the need of a duplexer.

 

[techguru]

I've revised this to include a major parts list. Cables and connectors one can figure out on their own. Now If I were building this I would box up all the equipment inside a fan vented weatherproof box to be installed at the top of a tower so that nothing but AC needs to be ran up the tower thus minimizing cable loss.

 

[prcguy]

It might work to some extent as an extender for a single user but none of the components are rated for continuous duty repeater operation. If you get a couple of people rag chewing on the components listed you'll be buying new components often.

The Baofeng handhelds are essentially a single chip receiver with virtually no front end preselection. At the very minimum you'll have to choose a 2m frequency who's 3rd harmonic does not land on your UHF frequency. Even with that figured out I think a Baofeng receiver on UHF will get blitzed by a 100w VHF transmitter in close proximity.

Antennas are one key to good repeater or any radio system performance and the little 4' 10" VHF you list would be unity gain or not much more, no matter what they claim.
prcguy

 

[Project25_MASTR]

There were some commercially available repeaters out there based off of HTs. One of note was the repeater Motorola provided the US Forrest Service and are often referred to as "lookout repeaters". They were essentially two current HT's (started with HT200's in the 60's) and 10W or 20W PA. Fairly low duty though.

Baofengs are rated to roughly a 5% duty cycle at high power. At low power (1W) that would be roughly a 25% duty. That setup may still get hot under use. The Mirage amp quoted will deliver run 1W > 75W or 5W > 100W. It should also be noted that the amp is rated for 50% duty at 100W output. At 75W (1W in) it would run around a 65% duty. There is still the risk of burning out the Baofeng in a good QSO.

 

[techguru]

After reading your replies I think a Mirage BD-35 would be more logical to use, not to mention cheaper.

This would also enable the setup to be reversed to VHF in and UHF out.

Are there any advantages/disadvantages to UHF in VHF out vs VHF in UHF out?

 

[prcguy]

I have a Mirage B-310G and its a nice little amp that does 100w out with 2w drive. It peaks out around 120w with higher drive. I use it with a KX3 on 2m SSB which is low duty cycle and it runs cool but long key down in FM mode with this amp is not a good idea.

Another problem I see is the VOX repeater controller. I have one of the Chinese units and it works well on handhelds running on batteries but I could never get it to work reliably with the handhelds running from battery eliminators. It will work once on the initial repeat mode key up then when repeat stops and the transmit radio unkeys it seems to make noise on the power line that gets picked up in the VOX controller and it keys up again and again in an endless cycle.

I tried bypassing each battery eliminator and adding big caps inside them to try and smooth out the power distribution but no luck. I was using Wouxun radios at the time, which are a little better quality than the Baofeng UV-5 series. In the end a cheap Chinese dual, tri or quad band mobile with built in repeat works every time, but not for high duty cycle.
prcguy

There were some commercially available repeaters out there based off of HTs. One of note was the repeater Motorola provided the US Forrest Service and are often referred to as "lookout repeaters". They were essentially two current HT's (started with HT200's in the 60's) and 10W or 20W PA. Fairly low duty though.

Baofengs are rated to roughly a 5% duty cycle at high power. At low power (1W) that would be roughly a 25% duty. That setup may still get hot under use. The Mirage amp quoted will deliver run 1W > 75W or 5W > 100W. It should also be noted that the amp is rated for 50% duty at 100W output. At 75W (1W in) it would run around a 65% duty. There is still the risk of burning out the Baofeng in a good QSO.