Milcom 220Mhz RF Amps

[fineshot1]

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.

[SlimBob]

It's probably a linear amplifier, as most of the 222MHz stuff had to use a narrow-spaced variant of SSB.

[tvsjr]

Crescend acquired Milcom a while back (1999). I've never dealt with anything Milcom-specific, but I've dealt with Crescend several times on both public safety and amateur systems, and have found them to be extremely helpful. Have you tried calling them directly to see if they can help you out?

[fineshot1]

Crescend acquired Milcom a while back (1999). I've never dealt with anything Milcom-specific, but I've dealt with Crescend several times on both public safety and amateur systems, and have found them to be extremely helpful. Have you tried calling them directly to see if they can help you out?

I was un-aware of that. All I knew was Milcom seemed to drop out of site. I'll do some google search's and see what I come up with. Thanks for that info.

[tvsjr]

http://www.crescendtech.com/about.html
(The first result for Milcom amplifier, by the way...)

[fineshot1]

Thank you - I emailed them. I'll let you know if I get a response.

[fineshot1]

Just as an update I finally spoke to someone at Crescend Technologies and they have no doc or brain power info
on these amps so I am on my own. I'll update again after I aquire a 24vdc supply so I can power it up and try it
out on the bench.

[fineshot1]

I seem to have hit a snag with this project. I have been informed by iota that my DLS75 is not able to be converted
from 12 to 24vdc as it was originally advertised. Any one have a recomendation on a good reliable heavy duty 24vdc
supply? I estimate that depending on how hard I drive this amp it will draw anywhere from 9 - 15 amps so I would
like to play it safe and obtain a 24vdc 20amp supply. I prefer the more effecient industrial switching supplies like
iota makes but am open to suggestion. TIA.....dan n2aym

[tvsjr]

Astron makes the LS18A which is rated 18A intermittent/12A continuous, about $150. Another option, though much pricier, would be a Duracomm DPS-27-25, about $350. Both are available through Tessco.

[fineshot1]

Astron makes the LS18A which is rated 18A intermittent/12A continuous, about $150. Another option, though much pricier, would be a Duracomm DPS-27-25, about $350. Both are available through Tessco.

Thanks - Not sure but I beleive that the Duracomm model you referred to above is made by IOTA for Duracomm and I took a look at that
and yes it is rather pricey but I do like the specs. The Astron is a little shy of current capacity as I prefer to overkill it with power supplies and I am not a big fan of the Astron line anyway. I scaned ebay but did not see anything that appealed to me. I guess I'll have to wait awhile till the right one and right price comes along. If anyone has any more suggestions I am still looking....dan n2aym

[mancow]

Is this the amp you are working with? This guy has a whole bunch of conversion info at the bottom of the page.

http://www.n2ckh.com/125m_rptr.htm

[fineshot1]

Is this the amp you are working with? This guy has a whole bunch of conversion info at the bottom of the page.

http://www.n2ckh.com/125m_rptr.htm

No - but its similar in its construction internally. There is less plumbing and sensing electronics and its in a different outer package.
N2CKH's mods do not help me - I am aware of his web site and have spoken to him. My main problem right now is time & dollars
needed for this project plus I need to find a 24vdc 20A robust supply.

It looks just like the one below made by the co that bought out Milcom some time ago.

http://www.crescendtech.com/pdf/P15900MHz.pdf

[fineshot1]

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.
EDIT: Also need to find some 24VDC fans and replace the old ones.