Amplifier recommendations?

[Chuck-KK4HP]

I’m looking way ahead right now but I am wanting some input on what amps I should keep an eye out for to use as a driver between the HL2 and my linear amp. I need a max of 50W to drive it to full output and I normally use 25-30W. I’m familiar with the Hardrock 50, are there any others kit or pre-built worth considering? 

[DL1YCF]

There is a strong recommendation AGAINST cascading three PAs,

the HL2 PA, the „intermediate“ PA you are looking for, and the

„final PA“. This may lead to instabilities.

Technically it is no problem to drive a 1000W PA

from milliwatt input (see e.g. Hilberling PA) it is FCC regulation

that is against selling this as a complete product.

So my recommendation is to get „somehow“ a PA with decent amplification

(say, 20 dB) which under FCC regulation means this can only be a „kit“

rather than a complete product (look for "Hardrock 500").

If you can be happy with 15 dB (5 Watt ==> 120 Watt) you find plenty of

„complete product“ options, but again (bottom line) go for a 20 dB „kit“.

Am 01.09.2023 um 17:59 schrieb Chuck-KK4HP <nfl...@gmail.com>:

I’m looking way ahead right now but I am wanting some input on what amps I should keep an eye out for to use as a driver between the HL2 and my linear amp. I need a max of 50W to drive it to full output and I normally use 25-30W. I’m familiar with the Hardrock 50, are there any others kit or pre-built worth considering? 

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[Ed Grafton]

I see no real issues with cascading amplifiers. Ham manufacturers do it all the time. Example: mw out of the RF board of a Kenwood TS-440 to a pre-driver, to a driver & then to the 2 final 2sc2879s all on one board.

So long as the intermediate amp is clean, it should work good.

I will be using the TS-440 final section with LPFs to drive 2- MRf157s. 

Another possible option is to bypass the attenuator, or change it out for one that attenuates less. This would be in a 600W-1.5kw SSPA.

Ed

[KP4RX - Ramon]

Chuck, to get 50w check out the micro pa50 as an option. If the SWR from the cascading amp stays under 2:1 I think it will get the job done.

73, de KP4RX

P.D. Your package is on the way!

[Kurt V.]

I don't see an issue cascading a extra amplifier. I have the Micro  PA50 and drive my OM2000+ amplifier. Signal is clean and works fine. 

I happen to have a OM2000+ and I am not willing to give up this marvelous amplifier. 

The Micro PA has built in filters. And I don't drive the amp to it's full capabilities. It is a rule of thumb to drive half of the rated power of an amplifier to avoid platter and harmonics. 

[Chuck-KK4HP]

Thanks all. When I was in broadcast the Harris TX had cascade amps, exciter cabinet drove solid state driver modules that drove the final PA. The micro PA 50 looks like a good place to start, watched a few reviews. It could serve double duty with my FT-817. Just researching now, looking forward. de KK4HP 

[Pez]

Hi Chuck,

I have both a Micro PA-50 and a MX-P50M that I have used barefoot, and to drive an OM2000A+ for testing IMD. A few of my findings that might help (YMMV!):

• I could achieve better IMD results with the MX-P50M 
• I could regulate the power much more consistently with the MX-P50M than with the Micro PA-50. 
• The Micro PA-50 would sometimes overshoot, or detect high SWR (when there wasn't) and go into alarm mode, even at the lowest output settings. Its gain appeared very different on different bands, too. 
• I dislike the overly aggressive alarm protection mode on the Micro PA-50, and the very noisy fan. When it alarms, you must hold a button to reset it - annoying (and not ideal for remote operation)
• I like the auto band switching, and the auto RF PTT on the Micro PA-50. 
• I can hear in my TX audio when the Micro PA-50 is being used as an exciter. It does sound a little less smooth. Not "bad", but it is not as transparent as the MX-P50M. 
• I have kept the MX-P50M in place and it has been working very well. I wish it had auto band switching, but I still like it a lot. I often use it barefoot at around 40w output and it has been great for this as well. 

73

[Ron Lewkowicz]

I find the micro pa50 very hard to set the voice level for SSB. You'll be taking and certain voice tones send it high and trip protection. It's SWR is maybe reported a little high but I was able to work with that. Fan noise is bad and doesn't cool well. Despite it's very aggressive protection the finals are blown after 3 months. Looks like they are cheap and easy to replace but I don't have time to look at it now. I am assume I can fix it. Dealer says yes I have warranty. Warranty is please buy and replace the MOSFETs yourself. So also looking for suggestions for small amp.

[Colin Larsen]

Have a look on-line, there is a mod that makes it less sensitive.

Colin

ZL2FL 

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[Chuck-KK4HP]

Here's another that I ran across. Seller/manufacturer is in Ukraine, I've purchased from other Ukrainian ham sellers in the past without an issue, abut 4 weeks delivery time. Amp is available with or without auto band switching. Seller has ebay listing or it appears you can buy direct. 

https://www.60dbm.com/product/50-watt-hf-6m-power-amplifier-for-yaesu-ft-817-icom-ic-703-705-elecraft-kx3-auto/

Eham review https://www.eham.net/reviews/view-product?id=15462

[Pez]

That looks really good! Thanks for sharing that Chuck. I have ordered one to try out!  :)

73 

[John Williams]

This amp looks remarkably similar to the predecessor of the hardrock amp. It was called the ARRLHBC amplifier second pass. The filter layout is the biggest hint. I built one and it ran very well. The use of the RD16HHF1 parts are quite robust. This looks to be an excellent choice for a modest boost in power for the HL2. Reasonable price too!

 

John W9JSW

 

 

 

On Sunday, 3 September 2023 at 12:55:47 pm UTC+10 Chuck-KK4HP wrote:

Thanks all. When I was in broadcast the Harris TX had cascade amps, exciter cabinet drove solid state driver modules that drove the final PA. The micro PA 50 looks like a good place to start, watched a few reviews. It could serve double duty with my FT-817. Just researching now, looking forward. de KK4HP 

On Saturday, September 2, 2023 at 6:34:22 AM UTC-4 kvla...@gmail.com wrote:

I don't see an issue cascading a extra amplifier. I have the Micro  PA50 and drive my OM2000+ amplifier. Signal is clean and works fine. 

I happen to have a OM2000+ and I am not willing to give up this marvelous amplifier. 

 

The Micro PA has built in filters. And I don't drive the amp to it's full capabilities. It is a rule of thumb to drive half of the rated power of an amplifier to avoid platter and harmonics. 

On Saturday, September 2, 2023 at 12:42:31 AM UTC+2 KP4RX - Ramon wrote:

Chuck, to get 50w check out the micro pa50 as an option. If the SWR from the cascading amp stays under 2:1 I think it will get the job done.

 

73, de KP4RX

P.D. Your package is on the way!

On Friday, September 1, 2023 at 10:59:09 AM UTC-5 Chuck-KK4HP wrote:

I’m looking way ahead right now but I am wanting some input on what amps I should keep an eye out for to use as a driver between the HL2 and my linear amp. I need a max of 50W to drive it to full output and I normally use 25-30W. I’m familiar with the Hardrock 50, are there any others kit or pre-built worth considering? 

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[Dan Baker]

After a carful study I decided to go ahead and do just that.

The Hermes-Lite II Plus drives a 50 watt Neptune made by 60 dBm, it drives a KPA500 and I am very happy with the way it works.

It does a fine job on VarAC, latency is not an issue in the handshake mode. 

One thing I added was a 10dB attenuator on TX between the Hermes and the Neptune. I did this because at the 

lowest drive level into the Neptune, it produced output peaks from the Neptune that were to high for the KPA500. 

The 10 dB attenuator lets me operate the drive around 50% to Neptune with a plethora of granularity.  

The integration went so well its as if the Hermes has a 500 watt internal PA. 

73, Dan KM6CQ 

[Chuck-KK4HP]

Thanks Dan, that’s good to know. I just got the tracking email that my HL2 has shipped. Once it arrives I’ll take a few weeks or so to get familiar with it then consider ordering that amp. A lot more confidence in it than one of the Chicom offerings and a good mid-level value.