For those of you who have not yet seen this video, it shows some remarkable
cooling progress being made to SS amplifiers. I hope that in the near future,
we'll see more SS amplifiers using closed-loop water cooling.
https://www.youtube.com/watch?v=gLCuWs5SdBI
Pau, W9AC
-----Original Message-----
From: Amps [mailto:amps-bounces@contesting.com] On Behalf Of Ken Durand
Sent: Tuesday, December 6, 2016 4:15 AM
To: 'Jim Thomson' <jim.thom@telus.net>; amps@contesting.com
Subject: Re: [Amps] Stock up on tubes?
Ampleon has added a new LDMOS power transistor to its family of extremely
rugged power transistors designed specifically for use in high power amplifiers
operating in the 10 to 500 MHz. Suiting use in a wide variety of broadcast and
industrial applications, and capable of operating with a VSWR up to 65:1, the
device is rated to deliver 1,700 Watt CW or 1,900 Watt pulsed.
https://www.everythingrf.com/News/details/3046-1900-watt-ldmos-power-transistor-for-broadcast-industrial-and-medical-applications
Ken
N4zed
-----Original Message-----
From: Amps [mailto:amps-bounces@contesting.com] On Behalf Of Jim Thomson
Sent: Monday, December 05, 2016 11:05 PM
To: amps@contesting.com
Subject: [Amps] Stock up on tubes?
Date: Sun, 4 Dec 2016 22:48:45 +0000
From: Bill Turner <dezrat@outlook.com>
To: Amps group <amps@contesting.com>
Subject: Re: [Amps] Stock up on tubes?
On Sun, 4 Dec 2016 15:43:53 -0600, Kim wrote:
>When the SS devices are as easy to use *and* and cheap enough to meet
>our current hollow state device's price point, vacuum tubes will go the
>way of the dodo. We're progressing rapidly towards that, but it'll be a while,
>yet.
REPLY:
In terms of the device itself, that day is already here. The LDMOS devices from
NXP are fully capable of replacing tubes in a legal limit amp and the price
already beats tubes too. A pair of them that easily puts out 1500 watts is
around $400. Compare that to an 8877.
You can be sure designers are working hard to build the circuitry around them
that will soon make tubes pretty much obsolete.
FlexRadio already has a legal limit amp that is awaiting FCC approval using
said devices and they expect approval before the end of the year.
As with everything, time will tell.
73, Bill W6WRT
## Problem with SS is..... they typ only run 50% eff. To get 1.5 kw CCS
output on
RTTY / FM, data modes, you require 3 kw dc input. 3000-1500 = 1500 W CCS
dissipation..
= 5115 BTUs.
## 1500 watts CCS dissipation is one helluva lot of heat to try and
dump....which is not going to
be quiet anytime soon. That would be a feat in itself... just check out
dishtronic.
## Then you require a myriad of 2 kw CCS rated LP filters, and be able to
relay switch em.
## Then you require the 2 kw CCS rated auto tuner...so the SS amp doesnt
blow its brains out....
ditto with the myriad of LP filters...and associated relays.
Plan B is use enough devices so its rated for 2.5 kw out into a 1:1 SWR, so
it will handle 1.5 kw
into a 2:1 swr. Then use LP filters that will handle 1.5 kw CCS into high
swr.
## Then you require the 50 –100 vdc switching type power supply... but that
is not an issue these days.
## Then cross your fingers that the end product doesnt have lousy IMD... like
dishtronics –30 db pep ( IMD-3),
which is no better than any sweep tube amp from the 70s.
## an auto tune tube amp is still the biggest bang for the buck..for now.
Any manual tune tube amp
is an even bigger bang for the buck.... provided you dont require instant band
change.
Jim VE7RF
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