Milcom 220Mhz RF Amps

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fineshot1
Posts: 72
Joined: Tue Jun 27, 2006 8:20 pm

Milcom 220Mhz RF Amps

Post by fineshot1 » Mon Jun 02, 2008 8:43 am

Anyone have any specs info on the Milcom 220Mhz rack mount rf amps for the defunct acsb trunk system line of equipment. I acquired one of these amps and its built like a tank and want to put in in fm repeater service and need the specs and any other info I can get. Its marked only as 28vdc on the power molex connector and a max of 150mW on the rf input N connector. There is no model number on this beast and very little to no info on the web. I know its very similar to the Uniden ARX2125 model but its less complicated on the innards. I know I can run it on 24vdc which is what I most likely will do since I can convert one of my iota power supplies from 12 to 24vdc. Any help or info would be appreciated. TIA.......dan n2aym

PS - I am aware of the n2ckh web site info and seeking something more towards anyones experience or specific info on Milcom International models.
fineshot1
NJ USA

fineshot1
Posts: 72
Joined: Tue Jun 27, 2006 8:20 pm

Re: Milcom 220Mhz RF Amps - Update

Post by fineshot1 » Wed Sep 17, 2008 3:24 pm

Bringing back this older thread for an update. I finally got a hold of a NewMar 24VDC 16 Amp supply and did some preliminary bench testing today.

With 150mW input into this amplifier I got 75W out of the directional coupler on the output. I bypassed the directional coupler
and got approx 87W on the ouput port of the amplifier. I measured the draw on the amp at approx 12.5 Amps which is a little
too close to the max on this supply for me but it should work for now until I can find a better supply. This amplifier draws about
5 Amps at idle as the active devices(5 of them) are wired hot all the time.

All testing done at 224Mhz using a Bird and a Moto 150W/300W dummy load and a GD R2670B service monitor. The output
looked very clean on the spectrum analyzer and I used a Icom IC-3SAT portable with a 3db attenuator to get down to 150mW.

Now I need to gather up some other odds & ends(cables, adapters,etc) and I can get it on the air on my repeater.
Also need to find some 24VDC fans and replace the old ones.
fineshot1
NJ USA

Slimbob
Posts: 16
Joined: Mon Jan 26, 2004 2:05 pm

Re: Milcom 220Mhz RF Amps

Post by Slimbob » Fri Feb 06, 2009 4:08 am

ACSB IIRC is single-sideband, so the amp should be linear, which means (barring poor IMD response) that you can put up more than one repeater using the same PA at one location.

fineshot1
Posts: 72
Joined: Tue Jun 27, 2006 8:20 pm

Re: Milcom 220Mhz RF Amps

Post by fineshot1 » Thu Feb 19, 2009 8:24 am

Yes - thanks. The amp works flawlessly, still have it at the shop. Ran my last test with a 25.5VDC 25A supply
and with 150mw input got about 95 Watts clean output. I will eventually install in my rack at the site but I will
have to take the entire rack apart and move everything around to get it to fit.
fineshot1
NJ USA

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