How much for an 8877?
https://www.ebay.com/itm/3CX1500A7-New-RLM-MICROWAVE-Full-Power-Out-Guaranteed-Buy-It-Now-325/322954029006?hash=item4b318f67ce:g:4QkAAOSwj99Z9Vzx
73
Jim W7RY
Merry Christmas
-----Original Message-----
From: kstover@ac0h.net
Sent: Sunday, December 24, 2017 8:09 PM
To: 'Bill Turner' ; 'Amps group'
Subject: Re: [Amps] NXP 65V LDMOS 1K80H-1800W
What happens when they quit making tubes?
I can think of one company making a CCS rated tube final amp (Alpha) and
they are hanging on by a thumb nail with their $6K amplifier. The 9500
won't
do CCS RTTY or FM at 1500 watts without auxiliary cooling for the power
supply.
Ameritron amps are not CCS rated, read the manuals. OM Power may be CCS
rated but they use those evil noisy Russian tetrodes. The blowers in these
amps are all famous for sounding like a Bell Jet Ranger lighting up but
it's
the noise that SSPA's make that always gets thrown out. Elecraft is
testing
a new cooling system for the KPA1500. New fans that turn slower, make less
noise and cool the amp just as well.
Any company producing an SS amp running 1.5Kw out with just one of these
LDMOS devices are idiots.
Everybody but SPE are using two.
I just looked at the price for a new matched pair of RF Parts 3-500ZG's.
$400. A new Eimac 8877 will set you back $1399, a pair of the these LDMOS
devices, depending on dissipation and voltage rating are a push for a pair
new 3-500's. These are all new prices.
The Chinese versions of the tubes are cheaper, about 50% cheaper, but they
could be gone tomorrow depending on which way the wind blows.
Point to all this is SSPA's are the future, like it or not.
-----Original Message-----
From: Amps [mailto:amps-bounces@contesting.com] On Behalf Of Bill Turner
Sent: Sunday, December 24, 2017 5:16 PM
To: Amps group <amps@contesting.com>
Subject: Re: [Amps] NXP 65V LDMOS 1K80H-1800W
------------ ORIGINAL MESSAGE ------------(may be snipped)
On Sun, 24 Dec 2017 08:49:23 -0800, Jim wrote:
## I would like to see what both these amp manufacturers have to say
about duty cycle.
If they are 1.5 kw ICAS, I will pass on em for now, not for the $7K
price tag.
REPLY:
Before anyone gets too enraptured over SS amps, you might want to
reconsider
the advantages of tube type amps:
1. With a pi or pi-L tank, no antenna tuner is required up to SWR of
about
3:1.
2. Likewise, no low pass filters.
3. Much more resistant to accidental overloads.
4. Heat dissipation is easy.
5. Usually cost less unless you want autotune.
6. 1.5 kW CCS is easily achievable, i.e. a single 8877 pr pair of
3-500Z's.
The most common limiting factor is the power supply, not the tube.
Drawbacks:
1. Warm up time with some tubes. Not an issue with 3-500Z's or other
filament-type tubes.
2. The cheaper ones are all manual tune.
You pays your money and takes your choice.
73, Bill W6WRT
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