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Re: [Amps] B&W PT2500

Subject: Re: [Amps] B&W PT2500
From: "Joe Subich, W4TV" <>
Date: Sat, 27 Aug 2022 09:25:57 -0400
List-post: <>

The PT2500 is (I think) 2 x 3-500Z.  The gain is already marginal
if trying to reach 1500W out with 100W drive.  Now, if one were
working with ceramic/metal tubes or solid state devices that reach
1500 W (or their 1 dB compression point) at 30W (as many do), a
2 or 3 dB attenuator is a very good idea for many reasons.


   ... Joe, W4TV

On 2022-08-27 12:47 AM, wrote:
For an input SWR when using a solid state amplifier against a PT2500 Amplifier, 
why not use something like this?  It will provide a 50hom load to the 
transceiver input  regardless of the band exercised.  They offer 1db, 2db on up 
of attenuation, and are matched at 50ohms to the Transceiver input of the amp 
all the way to 1Ghz or better. The point being here the transceiver will always 
see a ~50ohm load.  Just a thought.

Thank you,


-----Original Message-----
From: Amps <> On Behalf Of gudguyham--- via Amps
Sent: Thursday, August 25, 2022 11:48 PM
To: Bob Gibson <>;
Subject: Re: [Amps] B&W PT2500

Bob, I’ve got two of these amps in my shop now.  You should be aware that the stock open frame relay is 120vdc and most radios can’t handle this 
switching voltage/current.  You’ll need a buffer of some sort.  Personally I like installing a soft key internally.  You can use a Harbach SB220 soft key 
kit or a similar one completely assembled.  I have completely assembled soft key units.  Don’t try to key this amp without one!  Also, be aware that this 
amp does not have adjustable input networks like many other amps do.  Keep in mind that these amps were designed around being used with tube type radios with 
adjustable pi-networks.  Therefore the input networks only needed to be “good” as to present an “ok” swr to a tube exciter.  Using this 
amp with a solid state radio you may find that the input swr is less than stellar.  If it’s a bit high for a solid state radio they will fold back and your 
power output will be low.  Check your input swr!  If it’s poor there’s not much you can do about it except use the radio tuner.  The input circuits 
are buried and inaccessible.   Way before it’s time, this amp has a grid trip circuit which is factory set for 400ma.  Lou

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On Thursday, August 25, 2022, 11:38 PM, Bob Gibson via Amps 
<> wrote:

I have bought a B&W PT2500 amplifier and I looking for blower for the unit. If 
anyone happens to have a part number or where to find one..Please let me know..Also 
has anyone done any kind of a mods to one..20 meter output is low..

    73s Bob W5RG

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