Spectra(s) as a repeater

[n9wys]

I am trying to use two Spectra radios as a 900 repeater. I have been able to convert the radios to the ham 900 band for use as mobiles, but I need one to listen to the input frequency (in my case, 902.5250).

When I try to program in the input freq as the Talkaround freq, I get the error "Value outside the range for this model." I have LAB software, and this is what I have been trying to use for this project. I've also tried to reverse the frequency entries and get the same error...

Is there any way to get the Spectra to hear the input? Is it worth the effort?? I've read elsewhere that the Spectra doesn't hear very well at 902...

I believe that this is the final problem I have with making the repeater - unless I need to look at another model of radio for the receiver portion.

Thanks!

[kcbooboo]

The Spectra's front end is centered on 938 MHz. The filters will let you get adequate sensitivity down around 927, but probably not too much lower than that. I doubt you'll hear anything at 902.5. The VCO probably will require some tweaking to get it to work that low as well. The GTX mobile will probably have the same problems, in case you were considering using one of those as a receiver.

I found that the values in the programming software had to be patched rather carefully, mainly due to the way it figures out if you can even do talk-around or not. There's one freq range for normal transmit, one for talk-around transmit, and one for receive. If they overlap, talk-around may not even be an option. I don't know if your version of software also needs to be patched; it may let you exceed the freq ranges but it also may impose some other restrictions.

I think you'd get better results with an 800 MHz or 900 MHz MaxTrac as a receiver. At least the front end filters can be changed to give you great sensitivity at 902 MHz.

Bob M.

[n9wys]

OK, Bob. I was kind of afraid of that, but thanks anyway.

At least this kept me from cobbling the thing together only to find out it would't work as expected.

[Jonathan KC8RYW]

You could use a 800 MHz MaxTrac for a reciever. Just follow the mod directions on the Repeater Builder website.

[n9wys]

I picked one up off of e-Pay a few days ago - just waiting for the brown shirt crew to drop by the house with the battered box...

Once I get it, I'll do the required mods and see what happens.

Thanks!

[derekjmu]

what about using a 800 MHz MCS2000 as the receiver in a 900 MHz ham repeater? will it work like the maxtrac you described?

thanks.

[n9wys]

I suppose I could, if I had one to play with...

FWIW -- The Maxtrac showed up, and it has a 5-pin connector on the rear and is configured for one channel (talkgroup) only - trunked operation. I'm not sure I'll be able to convert it, unless I change out the firmware AND the control head. Probably more than I really want to jump in to for now.

So I guess that brings me back to the MCS2000 suggestion. Are these avaialable at reasonable pricing via the normal outlets (e-Pay, etc.) ??

Or maybe a GTX900??

Ideas?

[kcbooboo]

If there's an EPROM on the logic board, it can be replaced, and you can at least have a two-channel receiver.

The escutcheon on the control head can easily be replaced.

If the RF board is not capable of talk-around, you can still use it by mucking with the VCO to move it up in frequency. Change the filters or short them out.

You can always add your own COR circuit to any logic board, 5 or 16 pin.

It's not the end of life as you know it! Tons of good info for conversions over on http://www.repeater-builder.com

Bob M.

[n9wys]

I guess you're right, Bob... I was just looking for the "quick and dirty" way out of my situation.

I got my coordination about 4 months ago, and the clock is running... another 2 months and I'll need to apply for an extension to the construction permit. (Not that anyone is knocking down the doors at the IL Repeater Association to get a coordination on 900 -- other than one other ham I know of.

[n9wys]

Just an update...

I bought a MaxTrac that was converted to 902 RX... so I think I'm good to go there. I also bought a Glenayre 900 MHz paging station (300W PA) with the power supply, so that is good, too. And I have a TP-3200 for the controller.

Now the only thing I need to do is get one of these D@#% Spectras working!

I cannot seem to get the codeplug strings to match in the one that I'm working on (see other posts I've made regarding that) and until I do, I'm at an impasse. ARRRGH!!! However, the final piece to the puzzle will be pulling off about 150mW of drive for the Glenayre PA. I hate to end up using a perfectly good 35W Spectra (if it ever works like I want it to) as an exciter - since I'd rather have that for my mobile. But I haven't found any conventional 900 MaxTracs available lately...

I guess one question I have is - how easy would it be to use a GTX mobile in place of a Spectra/MaxTrac for the TX radio? I have several of those available.

There is one other possibility for my project, but I'll reserve that discussion for another time/place. In either event, I would like to be able to get this working - if for anything, a learning experience, and my sanity.

Thoughts / ideas? Thanks!

[recurry]

I have been using two Spectras as a repeater for about 8 years. I just recently took the system down due to lack of use and my getting tired of paying $100/month for rack space. Anyway, the Spectra make VERY nice receivers by removing the front-end cavity filters and either replacing them with a ceramic filter or putting pass filter external to the receiver.

Regards,
Ron
N6QL

[n9wys]

Thanks, Ron.

I ended up using a Maxtrac and a GTX in conbination for the repeater... been having way too much trouble getting error codes to clear on the Spectras I have, so I went an "easier" route. But thanks for keeping me in mind!

Now if those MSF5000's would just come available......

[recurry]

Thanks, Ron.

I ended up using a Maxtrac and a GTX in conbination for the repeater... been having way too much trouble getting error codes to clear on the Spectras I have, so I went an "easier" route. But thanks for keeping me in mind!

Now if those MSF5000's would just come available......

The error codes are probably VCO unlock codes due to the mod that's circulating not being a very good mod. Spectra's are great radios - far better than Maxtracs or GTX's but they are much more difficult to modify.

73 Ron N6QL