[Amps] B&W PT2500

[Joe Subich, W4TV]

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.

73,

    ... Joe, W4TV

On 2022-08-27 12:47 AM, w5cul at sbcglobal.net 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.
> 
> https://www.ebay.com/itm/370603866564?hash=item5649b639c4:g:s2sAAOSwLzdWRTy4
> 
> Thank you,
> 
> Mike
> W5CUL
> 
> -----Original Message-----
> From: Amps <amps-bounces at contesting.com> On Behalf Of gudguyham--- via Amps
> Sent: Thursday, August 25, 2022 11:48 PM
> To: Bob Gibson <w5rg at yahoo.com>; amps at contesting.com
> 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
> 
> 
> Sent from the all new AOL app for iOS
> 
> 
> On Thursday, August 25, 2022, 11:38 PM, Bob Gibson via Amps <amps at contesting.com> 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