2 Repeaters 1 Hardline/antenna

[otobmark]

. We actually had 16 2.4kW transmitters and had to use two uplink antennas

were you combining for power or bandwidth?Not a satellite guy but know broadcast (TV) stackup a pile of transmitters on same freq and phase. No clue how they connect them. Having worked sats on manpack I had absolutely no idea anyone shot that much power skyward. What you describe sounds more like a weapon 38kw straight up. Cook any birds?

 

[prcguy]

Combining for bandwidth. You have two polarities on satellite and about 500MHz of band width per polarity divided into usually 8 channels (transponders) per polarity on Ku with a small guard band between channels. Even though this particular combiner was lossy with about 7dB loss from the transmitters to the antenna feed, it was still a lot of power to play with. I remember the antenna had to undergo testing with 5kW per polarity into the feed, 10Kw total and that was a lot of heat. Antenna gain was somewhere around 61-62dB so the EIRP was epic.

So how is this related to the topic? I don't know. Moderator!

. We actually had 16 2.4kW transmitters and had to use two uplink antennas

were you combining for power or bandwidth?Not a satellite guy but know broadcast (TV) stackup a pile of transmitters on same freq and phase. No clue how they connect them. Having worked sats on manpack I had absolutely no idea anyone shot that much power skyward. What you describe sounds more like a weapon 38kw straight up. Cook any birds?

 

[davidgcet]

putting ham on the same tower as PS is not unheard of, what it appeared from the op was that this was trying to add in ham on an existing ps system which was in use. the natural assumption is that the ham is trying to cheap out, especially since the entire point was to ask how to do it cheaply with no concern for real advice.

 

[otobmark]

putting ham on the same tower as PS is not unheard of, what it appeared from the op was that this was trying to add in ham on an existing ps system which was in use. the natural assumption is that the ham is trying to cheap out, especially since the entire point was to ask how to do it cheaply with no concern for real advice.

Other way around, the amateur radio was in place and coordinated. Task Force has obtained some UHF pairs statewide for exploration into using DMR. I was trying to accommodate them by putting up spare repeater on the site tuned to one of their pairs which will most likely degrade my amateur repeater. I'm guessing the extra cans I will need to do this will cost ME $3K or more. They have other sites they can use with smaller footprints. Now they could persuade the city to bump me out all together. My repeater is home to Auxcomm hams and PS hams focused on our county and not a part of Brandmeister or any other worldwide network which we deemed detrimental to our mission. All commercial gear, new sinclair cans, installed to meet or exceed city requirements, no failures in 7 years. Outperforms the VHF repeater (analog) 20' higher up. The license is to a State Radio Engineer. The only thing amateur about it is the frequency.

"no concern for real advice" Ok that was cheap, false, petty insult to me and the others who have given me my starting point and may yet help me with any glitches that arise after assembly. I now have the measure of you....

 

[Flyham]

Bridgecomm was mentioned in this thread with reference to a setup they offered. Upon reading the thread, the thought from the below link also kept popping up in my mind.

Two Repeaters One Antenna Feed Line

We had an opportunity recently to provide a unique duplexer system. The customer needed a single antenna feed line for two repeaters. This solution saved the customer two costs. One, the expense of hiring a tower climber. Also the recurring cost of additional tower space rental for a 2nd feed...

www.bridgecomsystems.com

 

[buddrousa]

That is a made for device not some homemade so239 T

 

[otobmark]

Yep. I would only need the piece on top.

 

[rescue161]

Maybe I missed it, but I saw that the OP mentioned that the public safety will TX on one of seven repeaters. I'm also assuming that this a trunked or combined setup. If so, I'd also imagine that they are using two antennas. One for the 7 PS transmitters and one for the receivers. If that is true, you should be able to use your existing transmit cans (with a circulator) on the TX side and use your receive cans on the multicoupler. Again, I apologize if I missed it. It's hard to read everything on my phone.

 

[prcguy]

Yes, you would need that for two repeaters close in frequency like both in the amateur band. A "T" adapter and critical length cables will work fine with good duplexers and 20Mhz span between repeaters like one in the amateur band and one in the commercial band.

If you look at any duplexer they all have a T adapter and two critical length cables going to the receive filters and transmit filters and you are transmitting and receiving into the same coax, same antenna. What's the difference?

That is a made for device not some homemade so239 T

 

[buddrousa]

Just not the way I was taught in 1979 and 1980 at a Motorola Shop.

 

[Project25_MASTR]

Eh...I figure I will share these (some of the installs I've run across in my professional career occasionally show up here). This was when I worked for my previous employer (but this was one of the few times I was fixing another MR's install and not the one I worked for).

In this picture, the county was told their Road and Bridge repeater was no longer functional (the MTR2000) by the "local" one man reseller (who also was a ham) so a sales rep for our shop went ahead and sold a replacement (the VX-7000). Just so those know, all of this was alternate (primary was a multi-site VHF trunking system but poor performance from Kenwood radios and budgeting lead to non-critical stuff being moved back to conventional until APX's could be budgeted at a later date). Oh, that Bird is still sitting there for reasons unknown (the reseller left it).

Anyway, it took me a whopping 5 seconds to diagnose the MTR2000...

And yes, that was literally all that was wrong with it (it was on frequency and 100% spec'd out once I actually applied power to it). My theory was the reseller was trying to pad his pockets by just selling a new repeater and is why he told the county the repeater need to be replaced.

Anyway, that isn't the real reason I'm showing these pictures...this is.

Yes...splitting receivers on the pass band side of the duplexer.

One of the authors of the GCT has a saying.
"You can always tell a ham...you just can't tell him much."

 

[prcguy]

Using a T to split to two receivers is very bad practice. But using a T and proper critical length cables to combine two duplexers that can handle the separation is completely different, its a matched 50 ohm system by virtue of the critical length cables. If the duplexers can't handle it or you don't have the knowledge and test equipment to pull it off, then by all means please avoid it.

Otherwise hamsters will be hamsters.

Yes...splitting receivers on the pass band side of the duplexer.

One of the authors of the GCT has a saying.
"You can always tell a ham...you just can't tell him much."

 

[cmdrwill]

I wonder if prcguy remembers the 'tash mahall on Lukins?

 

[12dbsinad]

Eh...I figure I will share these (some of the installs I've run across in my professional career occasionally show up here). This was when I worked for my previous employer (but this was one of the few times I was fixing another MR's install and not the one I worked for).

In this picture, the county was told their Road and Bridge repeater was no longer functional (the MTR2000) by the "local" one man reseller (who also was a ham) so a sales rep for our shop went ahead and sold a replacement (the VX-7000). Just so those know, all of this was alternate (primary was a multi-site VHF trunking system but poor performance from Kenwood radios and budgeting lead to non-critical stuff being moved back to conventional until APX's could be budgeted at a later date). Oh, that Bird is still sitting there for reasons unknown (the reseller left it).

Anyway, it took me a whopping 5 seconds to diagnose the MTR2000...

And yes, that was literally all that was wrong with it (it was on frequency and 100% spec'd out once I actually applied power to it). My theory was the reseller was trying to pad his pockets by just selling a new repeater and is why he told the county the repeater need to be replaced.

Anyway, that isn't the real reason I'm showing these pictures...this is.

Yes...splitting receivers on the pass band side of the duplexer.

One of the authors of the GCT has a saying.
"You can always tell a ham...you just can't tell him much."

What a friggin mess that is... batteries in a card board box, fuse hanging in mid air, etc.. looks like you could hang yourself. It's not like there is a lot there to a least attempt at cable management.

 

[prcguy]

I've worked in several buildings on Mt Lukens and the last trip was to the big boy tower site in the middle of the complex about mid last year and it was reasonably clean. I rented space on one at the edge of the hill due south of the big boy tower owned by "Bob". It was kind of trashy at one point then most people got kicked out and the room got really cleaned up nice. Have not been in that bldg in years but a friend still has a rack of hammy stuff in there. Not sure which bldg you might be talking about.

I wonder if prcguy remembers the 'tash mahall on Lukins?

 

[DarcyB]

Yep. I would only need the piece on top.

which is nothing more than 2 4 cavity BandPass/Band Reject filters with a T between them, one side configured as a reasonably wide highpass filter, and the other side as a simular low pass filter. This setup works quite well, though the common issue is it can be quite lossy depending on freq splits and their associated knees.

 

[DarcyB]

which is nothing more than 2 4 cavity BandPass/Band Reject filters with a T between them, one side configured as a reasonably wide highpass filter, and the other side as a simular low pass filter. This setup works quite well, though the common issue is it can be quite lossy depending on freq splits and their associated knees.

and a link to the layout they used (also attached) https://cdn.shopify.com/s/files/1/0833/9095/files/System_2ch_Compact-_3_duplex_filters.pdf

 

[otobmark]

Oh geez, my machines will be deaf...
That slow dance between preamps and noise floor.

 

[Project25_MASTR]

What a friggin mess that is... batteries in a card board box, fuse hanging in mid air, etc.. looks like you could hang yourself. It's not like there is a lot there to a least attempt at cable management.

Yup. We weren't getting paid to clean it up, just install the new repeater and check the status of another. Unfortunately, in that area it is somewhat common for those sites to fall into disarray. I was going around to the different conventional sites in the area fixing and tuning systems as everyone was getting ready for bedlum when we turned off various trunking sites a day at a time (upgrading from Quantars to GTR's). Anyway, talk about forgotten sites...that one is only 1/4 mile and 100 foot elevation difference from the trunking site...the only two structures for a mile in any direction.