Call Search
     

New to Ham Radio?
My Profile

Community
Articles
Forums
News
Reviews
Friends Remembered
Strays
Survey Question

Operating
Contesting
DX Cluster Spots
Propagation

Resources
Calendar
Classifieds
Ham Exams
Ham Links
List Archives
News Articles
Product Reviews
QSL Managers

Site Info
eHam Help (FAQ)
Support the site
The eHam Team
Advertising Info
Vision Statement
About eHam.net

donate to eham
   Home   Help Search  
Pages: [1] 2 Next   Go Down
  Print  
Author Topic: Flex PowerGenius XL  (Read 2955 times)
K9RJ
Member

Posts: 69




Ignore
« on: October 24, 2017, 08:45:18 PM »

Does anyone have the full specs for this amp (not on Flex website that I can find): IMD, Hum and noise, and Harmonic output suppression. I would like to compare it to the ACOM 2000A as well as the Elecraft 1500 (specs not yet published) and the Expert Linear 1.5KW.
Thanks, Harris K9RJ
Logged
K6AER
Member

Posts: 4671




Ignore
« Reply #1 on: October 25, 2017, 09:36:49 AM »

The ACOM 2000 and the Expert 1.5 KW have been FCC type accepted. You should be able to read the report on the FCC web site. The Elecraft and Flex units may have already been submitted. A call to either manufacture should be able to direct you to the information you need.

By noise I am guessing you are talking about fan noise which any of these units will be a function of duty cycle. On all of these units, as the duty cycle increases, the fans speed increases at set levels. I know of no one who checks of fan noise at a set distance. The ACOM has two levels as with most new Tetrode amplifiers. Somewhat noticeable and full on for RTTY. On several amplifiers I have tested for fan noise,  the Alpha 8410 was 61 dBa at 18 inches on front of the unit at 1500 watts SSB. The OM-2000+ was 64 dBa it 18 inches in front same duty cycle. In both, I used an A weighted meter. I have not had the pleasure of testing any of the new solid state amplifiers for fan noise. At Dayton (Xenia) this year Flex had the Power Genius running all day long at 1500 watts out CW and I did not notice any fan noise.

The amplifier power supplies are very overbuilt but only the ACOM uses a transformer where HUM could be a normal part of the carrier. Hum would be most noticeable in the RTTY mode (highest duty cycle) but the FCC does not have a requirement for HUM as a percentage of output.

All the units will have harmonics well below the FCC requirement in order to meet type acceptance.
The ACOM unit does not have 6 meters and if that is your retirement the unit would be a non-starter.

Now we are down to IMD. Generally, a tube amplifier will have better IMD specifications. The FCC does not care about IMD on amplifiers as long as any interference is in band. Any amplifier with specifications better than 35 dB will be fine for the ham market. Most amplifiers are much better than the exciters driving them on IMD. Flex has released a paper in IMD at the Xenia  event this year. It should be available.
« Last Edit: October 25, 2017, 09:58:26 AM by K6AER » Logged
K6AER
Member

Posts: 4671




Ignore
« Reply #2 on: October 25, 2017, 11:21:58 AM »

Primary specifications for the amplifier are:

PA Specifications

•   RF Power Output: 1500W (ICAS)
•   Exciter Drive Level: 50W
•   Transistors: NXP MRF1K50H x 2
•   Exciter Inputs:1 SO-239 x 2
•   Antenna Outputs: SO-239 x 2
•   Antenna Impedance (w/o tuner): 50 Ohm Unbalanced
•   Cooling: Thermostatically controlled fans

Mechanical
•   Height:2 6.0" (15.1 cm)
•   Width: 13.8" (35 cm)
•   Depth: 19.7" (50 cm)
•   Weight: 37.4 lbs (17 kgs)
•   Operating Temperature Range: TBD

Electrical
•   Input Voltage:3 90 – 250VAC, 50/60 Hz
•   Power Supply: Modular internal switching


The transistor specification sheet is listed at: https://www.nxp.com/docs/en/data-sheet/MRF1K50H.pdf

Nowhere does the specification sheet go into IMD but the 1500 watt efficiency is listed 83% at 1500 watts. The amplifier uses two devices. With two 1500 watt devices being operated at a total of 1500 watts out the IMD should be in the -40dB range. Of the amplifiers listed the Flex should be the best bang for the buck in price, features, specifications and resale.

I might mention resale is a big factor for you don't want to find your self in the predicament the THP owners found themselves in when the company disappeared.

« Last Edit: October 25, 2017, 11:32:14 AM by K6AER » Logged
NO9E
Member

Posts: 714




Ignore
« Reply #3 on: October 26, 2017, 05:54:07 AM »

ACOM 2000A is old design. Quiet and tested but old. The current top_of_the_line are SPE 2k, 1.3k and 1.5k. All have at least 4 antenna outputs, with each matched by band and frequency. Instant band and antenna changes. Once you have and use it, there is no coming back. For radios with precorrection (Elecraft coming?), 1.5k with output for precorrection may be the best deal except for RTTY. All are more or less noisy but can be remoted (under desk). Apparently early 1.3k were noisy but the current ones are described as quiet.

I operated KX3 with 1.3k as CE0Y/NO9E with up to 3 antennas multi band, and the amp was invisible. Also not heard with headphones.

KPA1500 seem to be run_of_the_mill design, has two antenna outputs but may be designed as quieter and capable of 100% duty.
PowerGenius also has 2 outputs. Its specs show some ingenuity, including matching voltage to output power for max efficiency (= less fan noise). Perhaps also bias for mode.

It took SPE some time to make their amps reliable and refined.  Perhaps same with KPA1500 and PowerGenius.

Ignacy, NO9E

Logged
N2RJ
Member

Posts: 2014




Ignore
« Reply #4 on: October 26, 2017, 11:39:24 AM »

Ranko has said that he wanted to show the IMD of this amp alongside others. It's supposed to be cleaner than other LDMOS and even some conventional solid state and tube amps. The amp should meet FCC requirements quite easily and with adaptive predistortion it should be even cleaner. 
Logged
K6AER
Member

Posts: 4671




Ignore
« Reply #5 on: October 26, 2017, 06:03:13 PM »

Remember IMD is not a FCC requirement. Only harmonics, gain (less than 15 dB)  and no gain on 11 meters.
Logged
K9RJ
Member

Posts: 69




Ignore
« Reply #6 on: October 28, 2017, 10:58:57 PM »

Thanks for all the replies. I have an ACOM 2000A and know its specs and want to compare it to the new breed. Expert Linear provides full specs so that comparison is easy. I spoke with an Elecraft rep at Pacificon and he thought that the specs for the KPA1500 would likely be out in about a month. Apparently they are doing some last minute tweaking due to variations in parts specs (in part at least). So that leaves the Flex and I will pursue the details with them. As some have pointed out FCC does not require an IMD spec but my goal is to have the cleanest signal possible so it is important to me. Thanks again for all the responses, much appreciated.
Logged
AA4HA
Member

Posts: 2381




Ignore
« Reply #7 on: October 29, 2017, 09:00:26 AM »

Only amateurs can think that by not having an IMD specification it just makes it "OK" for the manufacturers to produce poorly designed amplifiers.

Overdriving the transistors to squeeze out the most gain while trying to get by off of a low voltage DC supply is guaranteeing that the amplifier will have a high IMD number.

We accept that its "OK" to trash up our own band and sort of tolerate that the FCC does not want us to do it elsewhere.
Logged

Ms. Tisha Hayes, AA4HA
Lookout Mountain, Alabama
Free space loss (dB) = 32.4 + 20 × log10d + 20 × log10 f
VK6HP
Member

Posts: 154




Ignore
« Reply #8 on: October 29, 2017, 10:33:47 PM »

Good posts Tisha and Harris - restores my faith in hamanity.  The message of personal responsibility makes a welcome change from reading in other threads about the relative merits of amplifiers with IMD figures that would make me ashamed to put them on the air.  I've signed up for a new Elecraft amplifier, which I plan to use in an SDR pre-distortion system. With any luck it'll actually be better than my 45 year-old Collins 32S-3/30L-1 combination Wink  

I guess the Flex amplifier will see similar service in many stations.  

73, Peter.
« Last Edit: October 29, 2017, 10:38:52 PM by VK6HP » Logged
K6AER
Member

Posts: 4671




Ignore
« Reply #9 on: October 31, 2017, 09:02:05 AM »

Only amateurs can think that by not having an IMD specification it just makes it "OK" for the manufacturers to produce poorly designed amplifiers.

Overdriving the transistors to squeeze out the most gain while trying to get by off of a low voltage DC supply is guaranteeing that the amplifier will have a high IMD number.

We accept that its "OK" to trash up our own band and sort of tolerate that the FCC does not want us to do it elsewhere.

Well this is an interesting rant. Please name the manufacture that pays no attention to IMD needs. SPE, Elecraft or Flex…All use 50 volt devices on their new solid state amplifiers and in the Elecraft and Flex they are using two 1500 watt transistors (LDMOS) to produce a 1500 watt amplifier. Typical  IMD on the new amplifiers is over -40dB for the third and fifth products. Ameritron is about 6 dB less but you get what you pay for.  Price on these units is north of $5900.

This bring to question how much IMD specification performance do you want to pay for? Will -45 dB be worth an extra $1500. With the exception of SDR base transceivers the average analog transceiver is lucky to have IMD two tone figures above 33 dB. So, all that fine engineering is lost when driven by a low performance radio which does not have the microphone gain knob removed. And yes, the mic. gain knob is the biggest contributor to excess band width SSB transmissions, by far.

You don’t have to overdrive solid state devices to get max power out. The have excess gain and in amateur applications, an attenuator has to be added to keep the gain below 15 dB (FCC spec.).

Power supply voltage on solid state devices has nothing to do with IMD. When the wave form reaches the rail voltage it stops producing higher wattage and your IMD goes through the roof. You have to not over drive the amplifier to keep it clean. This is not a design problem but an education problem. It is not up to the manufacture to train the ham community but for hams to Elmer new amateurs on how to set up station properly.

I wonder how many older tube amplifiers, that are so beloved in the ham community, would even pass a -35 dB  IMD specification. The new Tetrode designs will but not the older Grounded Grid units. I can tell you that base station amplifiers in the cell phone industry will not be above -40  dB on any of the spectrum bands. IMD on aircraft SSB units is about -35 dB.

The only time IMD is a real problem is when you have a high gain array up above 100 feet. Only then under proper band condition can you have a S9+40 signal. Then you run into radios that suffer poor front end and mixer performance and even if your signal was very clean they will hear you 10 KHz down the band.
« Last Edit: October 31, 2017, 09:13:28 AM by K6AER » Logged
N6YFM
Member

Posts: 502




Ignore
« Reply #10 on: October 31, 2017, 09:59:00 AM »


Overdriving the transistors to squeeze out the most gain while trying to get by off of a low voltage DC supply is ________

..is;  a multiple choice sentence completion.

Overdriving the transistors to squeeze out the most gain while trying to get by off of a low voltage DC supply is SO MUCH
LIKE CB RADIO...


And, K6AER, while I get what you are trying to say, supply voltage CAN help here.   
The linear amp companies that are designing LDMOS amps with a 50 volt supply instead of a 12 volt supply
are doing it for more reasons that just keeping the amperage lower.

Cheers
« Last Edit: October 31, 2017, 10:07:02 AM by N6YFM » Logged
KC4ZGP
Member

Posts: 1637




Ignore
« Reply #11 on: October 31, 2017, 10:54:03 AM »


And that's why I employ the Motorola EB-104 MOSFET amplifier.

50 big volts keeps everything clean as a whistle.

Kraus
Logged
K6AER
Member

Posts: 4671




Ignore
« Reply #12 on: October 31, 2017, 12:23:34 PM »

The reason we have 12 volt amplifiers are for mobile operation.

For base station operation the  50 volt LDMOS devices are much better for the higher voltage is the best match into 50 ohms with broad band magnetics of the splitters and combiners.
Logged
AC2RY
Member

Posts: 283




Ignore
« Reply #13 on: October 31, 2017, 12:31:54 PM »

Remember IMD is not a FCC requirement. Only harmonics, gain (less than 15 dB)  and no gain on 11 meters.

Actually there is a regulation that states emission levels outside of "authorized transmission bandwidth":

50% BW < fd < 150% BW  => -26dB
150% BW < fd ≤ 250% BW => -35dB
fd > 250% BW => 40 + 10 log(pX) or -80dB whichever is the lesser

All numbers are relative to Power Envelope (pX). See NTIE "Red Book" https://www.ntia.doc.gov/page/2011/manual-regulations-and-procedures-federal-radio-frequency-management-redbookNTIA

FCC does specify SSB signal bandwitdth (BW) on 60m band at 2.8kHz, but not on others. ARRL recommends less than 3kHz on other bands. IMD will cause emission outside of specified bandwidth and thus restrictions above should be applied.


Logged
W9IQ
Member

Posts: 1706




Ignore
« Reply #14 on: October 31, 2017, 12:43:33 PM »

Quote
IMD will cause emission outside of specified bandwidth and thus restrictions above should be applied.

Perhaps they should but in fact, they are not. A quick glance through the certification lab reports for part 97 amplifiers will make this clear.

- Glenn W9IQ
Logged

- Glenn W9IQ

I never make a mistake. I thought I did once but I was wrong.
Pages: [1] 2 Next   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.11 | SMF © 2006-2009, Simple Machines LLC Valid XHTML 1.0! Valid CSS!