repeater/amplifier attenuator fix?

[wqzw301]

I have an Icom fr-ic4000 repeater. I recently got a great deal on a Celwave 6 cavity pass/notch 100+dB rejection, professionally tuned. It really helps my sensitivity and selectivity on my front end. 

I have a Henry amplifier continuous, 10 in 70watts out. Which will give me about a 50watts output.

Problem is lowest setting on repeater is 25 watts. I do not have, the ability, or want to drop the low setting down to 10 watts and have it realigned. 

Would a 25watt 4db fixed attenuator, between the tx and amplifier be a fix. To avoid mailing the amp back to henry for an expensive retune, that I might want changed again someday.

I have a 50 ft run of 1/2" Heliax Cable to a CommScope DB404. RG400 on the repeater side. Plus, isolator on tx.

Please and thank you for any advice.

 

[Flameout]

Sorry I don't know the answer, but I have the same repeater, same antenna and same 1/2" hardline and was thinking about an amplifier and had the same question. Hopefully someone knows the answer. The one amp I was looking at (on ebay) was also 10w in.

By the way, does your FR4000 transmit your CWID on a scheduled time? I tried everything and now I'm not sure they are even capable of that

[SteveShannon]

45 minutes ago, wqzw301 said:

I have an Icom fr-ic4000 repeater. I recently got a great deal on a Celwave 6 cavity pass/notch 100+dB rejection, professionally tuned. It really helps my sensitivity and selectivity on my front end. 

I have a Henry amplifier continuous, 10 in 70watts out. Which will give me about a 50watts output.

Problem is lowest setting on repeater is 25 watts. I do not have, the ability, or want to drop the low setting down to 10 watts and have it realigned. 

Would a 25watt 4db fixed attenuator, between the tx and amplifier be a fix. To avoid mailing the amp back to henry for an expensive retune, that I might want changed again someday.

I have a 50 ft run of 1/2" Heliax Cable to a CommScope DB404. RG400 on the repeater side. Plus, isolator on tx.

Please and thank you for any advice.

 

Why not just set the IC-FR4000 to 50 watts and run it through the duplexer and skip the amplifier?

[kidphc]

Why not just set the IC-FR4000 to 50 watts and run it through the duplexer and skip the amplifier?

Can it handle that duty cycle?

Most of the repeaters in this area are 50w capable turned down to 25-30w. To increase available duty cycle and not burn the finals out.

Personally, I wouldn't add an amp to a repeater. To me it is just another maitenance item and failure point.


Sent from my SM-S901U using Tapatalk

[wqzw301]

I would like to have a 50watt output. 50 watts put me down to 25 watts...

Which I have no problem with low wattage. But I live in the city and twice the wattage gives me about 3-4 more miles.

Thanks

d

 

[Lscott]

3 minutes ago, Sshannon said:

Why not just set the IC-FR4000 to 50 watts and run it through the duplexer and skip the amplifier?

That's a good suggestion. Also want to mention the loss through the duplexer could be made up with a higher gain antenna too.

Some repeater owners have complained about desense on the RX section of their setup. It seems counter intuitive but DROPPING the transmit power level improved things.

Think about what exactly is going on. The antenna is being used for both TX and RX simultaneously. The higher TX power also will be coupled back into the RX section. To maintain the same isolation margin would require more isolation in the duplexer. Since the duplexer hasn't changed you effectively REDUCED the gain margin as seen by the RX section..    

[wqzw301]

11 minutes ago, Sshannon said:

Why not just set the IC-FR4000 to 50 watts and run it through the duplexer and skip the amplifier?

 

15 minutes ago, Flameout said:

Sorry I don't know the answer, but I have the same repeater, same antenna and same 1/2" hardline and was thinking about an amplifier and had the same question. Hopefully someone knows the answer. The one amp I was looking at (on ebay) was also 10w in.

By the way, does your FR4000 transmit your CWID on a scheduled time? I tried everything and now I'm not sure they are even capable of that

Yes my fr4000 does have a cwid. I haven't been in the programming for a while. I have to charge my Panasonic windows 7 laptop, too check the settings. When I can, i will get back yo you

[wqzw301]

6 minutes ago, kidphc said:

Can it handle that duty cycle?

Most of the repeaters in this area are 50w capable turned down to 25-30w. To increase available duty cycle and not burn the finals out.

Personally, I wouldn't add an amp to a repeater. To me it is just another maitenance item and failure point.


Sent from my SM-S901U using Tapatalk
 

Icom fr-3000 and 4000 is bulletproof at 50watts. Later icom repeaters are not.

 

[SteveShannon]

36 minutes ago, wqzw301 said:

I would like to have a 50watt output. 50 watts put me down to 25 watts...

Which I have no problem with low wattage. But I live in the city and twice the wattage gives me about 3-4 more miles.

Thanks

d

 

Really?  A Celwave duplexer costs you 3dB?  I thought that they were a lower loss duplexer. That’s more in line with a cheap duplexer from Ali Baba. 
Did you measure it on both sides of the duplexer?

[kidphc]

Icom fr-3000 and 4000 is bulletproof at 50watts. Later icom repeaters are not.
 

Ok.

The repeaters that were tuned down were Motorola Quantars. Which I view as nearly indestructible.

Sent from my SM-S901U using Tapatalk

[Flameout]

1 hour ago, kidphc said:

Can it handle that duty cycle?

Most of the repeaters in this area are 50w capable turned down to 25-30w. To increase available duty cycle and not burn the finals out.

Personally, I wouldn't add an amp to a repeater. To me it is just another maitenance item and failure point.


Sent from my SM-S901U using Tapatalk
 

I'm not 100% sure when it says 50w at 100% duty cycle, but according to this, it is capable of it. Mine is only putting out about 40 watts before duplexer and about 26 watts after. I'm using the Icom duplexer that it came with. Not sure who makes it or if it's even a good one

[kidphc]

I'm not 100% sure when it says 50w at 100% duty cycle, but according to this, it is capable of it. Mine is only putting out about 40 watts before duplexer and about 26 watts after
http://files.mygmrs.com/forums/monthly_2023_06/Screenshot_20230622-160612_Drive.thumb.jpg.324b0ed39e998347b74703b8bb505ce1.jpg

I asked the owner of the repeater (owns about 6 in the D.C. area). About the 100% duty on the Motorola Quantar.

His answer which is stereotypical of him was "its a 100% duty cycle till it isn't anymore". Hence, why he tuned them all down to 35 watts. He said they rarely fail at that point minus a lightning strike etc.

Sent from my SM-S901U using Tapatalk

[MarkInTampa]

Is this what you were looking for?

 

If you can't get to set mode it may be locked out. See this pdf to enable set mode https://manualzz.com/doc/19316255/fr3000-repeater-set-mode-adjustment.pdf

[Flameout]

On 6/22/2023 at 3:10 PM, wqzw301 said:

 

Yes my fr4000 does have a cwid. I haven't been in the programming for a while. I have to charge my Panasonic windows 7 laptop, too check the settings. When I can, i will get back yo you

Not to be a pain, but have you had a chance to look at your settings or your xxx.icf file? I think we must have the last 2 of these radios in existence. Even Icom wasn't able to help me. There has to be a working xxx.icf file out there somewhere, but it is very elusive