Roger there on the comments below Jim.
For adventurous homebrewers here's an interesting article on an alternative
novel approach to SSB generation and its efficient switched-mode
amplification by K1LI and K1KP in the March/April 2017 QEX magazine, pages 3
to 9. It uses a modern digital implementation of novel modulation concepts
long ago proposed by Leonard Kahn.
Whilst I like the polar IQ modulation and efficient switching RF amplifier
architecture and its novelty I must admit I'm a bit old school when it comes
to SSB generation and its associated low efficiency linear amplification...I
also don't mind having a lot of "big iron" to crank out legal limit PEP and
above for copious headroom.
Unlike radio broadcasters, for the modest amount of time an amateur station
is on-air, efficiency and the electricity consumption/conservation is not
such a serious driver...
Leigh
VK5KLT
-----Original Message-----
From: Amps [mailto:amps-bounces@contesting.com] On Behalf Of Jim Thomson
Sent: Sunday, 23 April 2017 2:27 PM
To: amps@contesting.com
Subject: [Amps] Price per Watt Conversation
Date: Sat, 22 Apr 2017 20:20:30 -0400
From: "Roger (K8RI)" <k8ri@rogerhalstead.com>
To: amps@contesting.com
Subject: Re: [Amps] Price per Watt Conversation
There was such a device listed on here just a few days ago, rated at 2KW
"carrier" MAX for $250 ea. A pair running 1500 out would be very
conservative. It's a given that running them at max would result in
short lifetimes, but a pair at 1500 should last a very long time and at
a cost comparable, even better compared to conservatively rated,
imported tube amps at 1500 out.
Found it:
http://www.richardsonrfpd.com/Pages/Product-Details.aspx?productId=1241241
Browser history can be handy at times.
73, Roger (K8RI)
## Ok, $250.00 EACH. So what. If 4 of em are used, the price tag of the
1.5 kw amp just rose from say $7k to $7.5K In the bigger scheme of things,
that extra $500.00 is going to be money well spent. Pay once, cry once.
## Leigh is correct, when they say CW....they mean dead cxr.... and not
keyed CW. On any of these SS xcvrs currently being produced, they all draw
normal idle current when used in keyed CW mode...and ditto with SS xcvrs no
longer in production. IF they were biased into deep class C, they would only
be useful in FM mode. On CW, they would no doubt create key clicks.
## How far apart can each device in a paralleled pair be....and still
function in the RF environment ?
IE: IF they have to be packed tight together, heat will still be an
issue...if the pair of devices are just inches apart.
## I noticed on these SS switches, used to turn on + off AC power, like
the large types, rated at 20-80 amps CCS, used in both single and 3 phase
power, they required SEPARATE massive .25 inch thick aluminum plates for
EACH device. Some were 12 x 12 inch x .25 A lot of em are bigger still.
And they dont mean a single 12 x 24 plate, with 2 x devices, with just 2
inches separation between them. One of the examples they used was a 150 HP
electric motor, running on 600 vac 3 phase, and 60 hz. The devices could be
paralleled for more current, and series for more V. They had also factored
in the start up current, with a loaded 150 hp motor, which is typ triple the
running current on some motors..and as much as 7 times the running current
on other types of electric motors.
## I used a simple contactor, less hassle, and no heat sink required, but im
OT here.
## I forget what the typ push pull SS amp does for harmonics. I think it
was high for the even harmonics, like 24- 40 db...and very poor for the odd
harmonics...like 12 db.
Without the use of a diplexer, that is one helluva lot of power being
reflected back by the LP filter... reflected right back into the final pa
section...further cooking the final pa...degrading imd, etc, etc.
Jim VE7RF
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|