RF Power Amplifiers
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Patrick Anglum
Nov 7, 2023, 11:09:26 PM11/7/23
to Hermes-Lite
Just curious what PA folks are using.
I assume the Hardrock 50 is popular.
How about this one
or this one
Anyone tried either of those? The one is 100 watts.
Colin Larsen
Nov 7, 2023, 11:18:13 PM11/7/23
to Hermes-Lite
There is a + (plus) version of the PA50 out that addresses some of the issues with it. Try and get that one if you can.
Colin
ZL2FL
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"Christoph v. Wüllen"
Nov 8, 2023, 10:27:08 AM11/8/23
to Colin Larsen, herme...@googlegroups.com
I have used the BLA350 with great success with the HL2, it only needs
a RCA cable (PTTEXT ==> PTT input of PA) and a coax (RF) cable.
It is rated 300 Watts and delivers about 120 Watt
when driven with a HL2 (nominal input power 1 - 12 Watt).
It works with 50 Volts (two MRF150) and has a built-in power
supply so it is driven from mains (110 or 230 or 240 V AC).
web site of manufacturer:
https://www.rmitaly.com/en/product-category/linear-amplifier-en/ham-en/linear-amplifier-ham-dc-en/linear-amplifier-ham-ac-en/linear-amplifier-ham-ac-hf-en/
(Note: I own the BLA-350, it seems to be replaced by a BLA350-plus now. But the specs are essentially the same)
I like this machine, just to let you know.
Christoph DL1YCF.
a RCA cable (PTTEXT ==> PTT input of PA) and a coax (RF) cable.
It is rated 300 Watts and delivers about 120 Watt
when driven with a HL2 (nominal input power 1 - 12 Watt).
It works with 50 Volts (two MRF150) and has a built-in power
supply so it is driven from mains (110 or 230 or 240 V AC).
web site of manufacturer:
https://www.rmitaly.com/en/product-category/linear-amplifier-en/ham-en/linear-amplifier-ham-dc-en/linear-amplifier-ham-ac-en/linear-amplifier-ham-ac-hf-en/
(Note: I own the BLA-350, it seems to be replaced by a BLA350-plus now. But the specs are essentially the same)
I like this machine, just to let you know.
Christoph DL1YCF.
John
Nov 8, 2023, 10:35:22 AM11/8/23
to Patrick Anglum, Hermes-Lite
The first one appears to have zero output filtering.
John K5MO
Max
Nov 8, 2023, 12:31:34 PM11/8/23
to Hermes-Lite
https://www.dxworld-e.com/product-page/hf-6m-linear-amplifier-500w
Full power output with HL2 when attenuator board on input is bypassed. incredible value for a relatively high power amplifier. Built like a battleship. Plenty space inside to make it easy to work on/modify if needed. Excellent protection circuits. Ubiquitous MFR300 x2 cheap to replace in unlikely event of being needed. 1kW version also available.
Only down side it is physically quite large (but NOT heavy). Needs 50v PSU. I use Eltek Flatpack2 server PSU - can be had low cost (should be no more than about $80 and sometimes much less) on eBay or computer surplus traders.
73
Max
Chuck-KK4HP
Nov 8, 2023, 12:57:08 PM11/8/23
to Hermes-Lite
A number of us have either of these. They are clones of the Hardrock without all the computer stuff. You can get the manual band switching model or the auto band switching model which is what I have. I think it was 18 days shipping from Ukraine. They are rated for full output all modes key down 24/7/365 like an Alpha :-) Mine did 70W with full HL2 drive, I dialed it back to keep it at 50W. The transistors are rated for >16W so that's 64W that you can output without exceeding the rating.
Manual
Auto
Rick Langford (N8SDR)
Nov 8, 2023, 1:10:11 PM11/8/23
to Hermes-Lite
I use a 1KW single pallet VK3AMP. Setup for low drive input.
2-4 watts produces easy 800-1100+ , very easy to control output power via Thetis slider
Very clean amp also has built in sampler for pure signal
Great support and very easy to work with.
You can get kits or assembled and tested, just email them for info.
VK3amps
Ron Lewkowicz
Nov 8, 2023, 1:41:59 PM11/8/23
to Hermes-Lite
I did try the second model you list the Micro PA50. After about 3 months the mosfets blew out and I'm still not quite sure exactly why. I had trouble finding support to get the correct drain current and after 3 or 4 unsuccessful attempts to replace them the pads finally lifted off the PCB. The designer now does offer support via a private facebook group. https://www.facebook.com/groups/6090995314269480 All the instructions are now in this group. If you plan to use this inside take note that the fan is very, very loud and cooling IMHO is not great. Apparently the amp is intended for outdoor use. Some other issues have been addressed in new firmware and there is a video showing the device required for programming posted. It's a very compact little unit so for POTA, SOTA etc. you might like it. For a full time amp for the shack I would look at some of the other suggestions given here. I'm currently strongly considering an RM Italy HLA-305V. Dxengineering carries them for North American.
The other amp you posted is useless without filters.
Max
Nov 8, 2023, 3:25:29 PM11/8/23
to Hermes-Lite
Ah yes, I forgot, I also did initially use RM Italy amplifier. The HLA-150v Plus. Nice amp with clean output when driven to about 1/2 to 2/3 of the rated power output, so about 80-90 Watts which given it was rated for 10W input it did automatically when driven with 5W from HL2. Auto-sense band switching worked flawlessly. I can recommend this amp especially if picked up for good price used. Keeping mine for mobile/portable use.
73
73
Max
Abuck289
Nov 8, 2023, 4:35:41 PM11/8/23
to Hermes-Lite
Interesting, I had not seen the 60dBm product before. It looks like they did a nice copy of the Hardrock-50's amplifier circuit. For $100 less you lose features like a wattmeter, SWR indication, temperature, automatic band selection (which is not the same as frequency detection), COR, QSK option, FCC Type Acceptance and remote control.
From the pictures it looks like they had trouble understanding/copying the HR50 output transformer which probably explains why the IMD is worse than the HR50.
The other thing that's missing in the ability to add an ATU inside the case that is fully integrated with the amp.
I probably get one and bring it to Dayton next year so you can compare them side-by-side.
73,
Jim WA2EUJ
On Wednesday, November 8, 2023 at 12:57:08 PM UTC-5 Chuck-KK4HP wrote:
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