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Reviews Categories | Amplifiers: RF Power - HF & HF+6M | HF Packer Amp: miniHFPA & miniHFPA2 Edition Help

Reviews Summary for HF Packer Amp: miniHFPA & miniHFPA2 Edition
HF Packer Amp: miniHFPA & miniHFPA2 Edition Reviews: 6 Average rating: 4.8/5 MSRP: $$349
Description: his project parts and your efforts will eventually provide
you with a compact 1,2.5 or 5 watt input to 30-35 watt
output linear amplifier for use with QRP SSB/CW transmitters
on the amateur bands 80 through 10 meters and which can be
frugally powered from a 12 volt battery. The design is a
good balance between output power, physical size and battery
power consumption. The completed amplifier will reward the
builder with a clean, more powerful output signal for a QRP
rig when radio conditions become marginal.
Product is in production.
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You can write your own review of the HF Packer Amp: miniHFPA & miniHFPA2 Edition.

G3YTU Rating: 4/5 Jul 12, 2018 15:16 Send this review to a friend
Companion Amplifier to FT-817ND  Time owned: more than 12 months
Dispatched: 22nd March 2017
Built: 21st June 2018
PCB Version MiniHFPA R2 / Old Style Heatsink

Options Purchased:
• Low Pass Filter Modules (a) 80/75M (b) 60/40M (c) 30/20M (d) 17/15M (e) 12/10M and the additional filter for 160m.
• Switch Guard (requires drill and install by builder).
• Fabricated RF Coils and transformers kit.
• Low Profile Heat Sink Plate. Includes all mounting hardware, MOSFET's, ceramic washers and thermal grease. Just received – to be installed later this year.

The miniHFPA R2 (Old Style Heatsink) kit was purchased as a companion to my FT-817ND transceiver for portable operation where the extra transmitter power would be useful.

The version of the kit I purchased required the installation of more components and soldering than the current version of the kit which makes it an even better deal.

Drilling of the switch guard and the front panel requires some careful work but went very easily which wasn’t what I expected.

A good set of tools and a bit of patience is required but for a little effort you get a lot of satisfaction having built it yourself.

I am glad I built this amplifier kit myself and even at 65 years old I learnt a few new things in the process and it looks good alongside the other commercial radio equipment.

(This review will be updated with some news on /Portable operations after this summer).
K3RNC Rating: 5/5 Apr 27, 2018 18:50 Send this review to a friend
Super product and support!  Time owned: more than 12 months
I purchased my Mini HFA (“Packer”) amplifier pre-built by Virgil Stamps K5OOR, and have been using it for a little over a year now. I feed it with a YouKits HB1B QRP rig rated at 4 watts. My power supply is a 5 AH sealed lead-acid battery (separate from the QRP supply), which powers the amplifier for 3 or more hours of operation on a charge. My shack with my 100-watt transceiver is in the attic, and when it’s too hot or cold, I operate with the QRP and Packer from a secretary in the den. The Packer is compact; QRP, Packer, tuner, batteries, key and cables all fit into the secretary shelf for closed storage, and there is plenty of space to operate with the secretary open. Operating QRP as a primary mode is tough when conditions aren’t great. With its 30 + watts, the Packer gives me nearly as effective a signal as my 100-watt transceiver. Due to my situation I have operated the Packer for many hours. I have also used this rig in the field on a couple of occasions, and it works fine there too, feeding a long wire with a tuner or a windom antenna.

The Packer has been trouble-free. I had an issue with the Packer shutting down for high SWR on 20 meters with my attic fan dipole (40, 20, 15, and 10 meters), but we traced that down to needing a choke on the feedline due to the short vertical drop of the feedline at the antenna. While we were trying to figure that out, I took Virgil up on his offer to take the Packer back and check it out. He also replaced the low pass filter for 20 meters while we were trying to figure out the problem. He really stands behind the rig.

I am not associated in any way with HFProjects aside from being a happy customer.

R. Neill Carey K3RNC

K2UM Rating: 5/5 Apr 3, 2018 11:29 Send this review to a friend
Excellent form, function, performance and price  Time owned: 3 to 6 months
I've owned and operated a miniHFPA2 for about four months. I've used it in the field during winter treks in Maine as well as at my home station. This amp is super lightweight, has a very slim form factor, is well designed and the output signals look great on a spectrum analyzer and o'scope. The output of 30 to 50 watts puts a QRP radio capable of 2-5 watts input into virtually the 100 watt output class of radio in terms of any real discernible difference in S-units or perceived loudness at the reception end. The amp sends out a nice clean signal and can be keyed via a relay or via automatic sensing and has a switch for amp switching delay for CW (QSK) or SSB (a slight delay in tx/rx changeover). I have used this amp for PSK31 and FT8 with a KX3 as the exciter and have not had any problems of heat dissipation or other heat related problems. I have not had to use an external fan for the digital operation, but so far my field use has been in cool/cold temperatures with good natural air flow around the amp. But, I have not had heat problems with digital operation at home as well.

I have found this amp to be a huge improvement over previous renditions of the HF Packer series designed by Virgil (with the input of many cooperators and users .. a neat way to develop a product of this type). I really like the high SWR detection/shut down feature as that has saved me a few times, especially in the field where operating conditions sometimes contribute to antenna changes (wind, ice, snow, breakage etc.). I love the idea of being able to change out LPF modules, but do agree that they tend to work loose during hiking and transport during outdoor activities. Independently, I came up with an almost identical solution as the reviewer who posted before me. And, knowing Virgil, he'll come up with a fine solution. It is no big deal to check the security of the modules in the field, save for the small screws for the side plates that can get lost among a clutter of forest under-story, rocks, or in my case snow. Predicting this as a possible problem, I always bring a couple extras with me.

My amp probably has at least a couple of hundred hours on it with 50% being in the field and the rest at my home station. It has been 100% reliable with no problems or glitches. I couldn't be happier with it. And, dealing with Virgil is always a joy due to his commitment and truly caring about the end users/operators. Most of all, Virgil is a true gentleman and is an example of the best in amateur radio.

Bottom line: An excellent product that has served me well .. well enough that I recently ordered a second one to present to a fellow ham.
W7BV Rating: 5/5 Mar 19, 2018 09:40 Send this review to a friend
Excellant, compact amp for QRP rigs  Time owned: 3 to 6 months
I fully agree with the VK4JAZ review. The miniHFPA2 amp boosts the output from QRP rigs to 30-50 watts depending on the output wattage from the QRP rig. It is a very compact and lightweight amp and perfect companion to my LNR MTR-5B with which it interfaces seamlessly and forms a very portable package. The only problem that I have discovered is that the LPFs, which plug-in through the removable side panels, can loosen and become ajar during transport; the resulting poor connections can cause blown finals. Virgil is aware of this problem and plans corrective action. I resolved the problem by adhering a thin piece of foam to the inside of the side plates to abut against the edges of the LPF boards to keep them from jarring loose during transport, e.g., in a backpack/suitcase. Finally, Virgil's responsiveness and service is outstanding.

VK4JAZ Rating: 5/5 Mar 18, 2018 16:16 Send this review to a friend
Great for ensuring QSOs in the field when conditions are poor.  Time owned: 3 to 6 months
I have used this amp now for a few months and have found it to be wonderful. I particularly like the fact that it can be powered by a battery, something that makes it an excellent choice for portable work. I use mine when activating SOTA summits or WWFF parks.

On my most recent activation, I logged 9 contacts on 40m SSB, using an FT-817, Buddistick antenna and, of course, the mini HFPA2 powered by a 7 a/h gel cell. At the start of the activation the battery registered 12.69 V, and by the time I packed up (47 minutes later) it was down to 12.60 V. To put this into perspective, I was calling continuously, and putting out 30 W. The heat sink on the amp hardly warmed up during that time!

The heat sink is something else I really like about this amp. It's not the usual type that features large fins that can be problematic when tossed into a backpack; this one is an integral heat sink plate where the internal heat producing components are thermally attached.

The amp features a lightweight but strongly fabricated and finished aluminium case, black anodized with white silkscreen text.

This amp comes with two fabricated, tested and aligned Low Pass Filters (60/40M and 30/20M). These are slotted into the two side panels that permit access to the plug-in modules should you wish to change them to work different bands. Additional modules are available for all bands from 160M to 10M. I have found that it's best to select which bands you intend working beforehand and fitting the appropriate LPF modules, as unscrewing the side panels could result in loosing the flush mount screws when out in the field in harsh operating environments.

Bands are selected by the front mounted toggle switch; the front green LEDs automatically indicate what band has been selected.

For portable use, there are very few options when it comes to linear amplifiers. This one ticks all the boxes. I have received nothing but excellent reports on the quality of my signal, the audio, and the signal strength. And, of course, customer support supplied by Virgil Stamps is now legendary.
AL5M Rating: 5/5 Mar 2, 2017 07:52 Send this review to a friend
An excellent update to a high quality, portable amplifier.  Time owned: 0 to 3 months
This is the latest design of Virgil Stamps, K5OOR at He eliminated the cables and packaged it into a 6" x 6" x 2.5" package. Mine weighed 1 pound, 9 ounces with two Low Pass Filters (LPF) attached. Very packable. You have the option of either a 5, 2.5 or 1 watt input giving you the ability to extend the battery life on your rig. Virgil has updated the circuitry and you have the ability to plug in two LPFs giving you four bands at any given time. LPFs for 10 through 160 are available. Two are included in the kit price. Virgil's customer service is unmatched. He will make sure you don't fail building this project.

I recently completed building the miniHFPA and had some mixed results during the power output test. The high SWR circuit LED would
activate periodically. Power output was inconsistent across the bands.
I replaced the IC (U2 Microcontroller) Virgil reprogrammed to correct this situation and I also changed the Pi-resistive network to a 5 watt input instead of 1. The reason I did this is I use an Elecraft KX3 for both a base & portable station. The tuning mode is set at 5 watts and I didn't want to accidentally overdrive the amp when tuning the radio. I would forget to reset the tuning mode power and end up spoiling a good walk with my rig.

I reset the bias & ran another test on all bands with 5 watts output. I use an Elecraft W2 wattmeter reading the results on my laptop with Elecraft's utility. My dummy load is an Oak Hills Research 100 watts, 50 Ohms and my power supply is an Astron SS-30M. I measured the Ampres with an inline watt meter/power analyzer by Turnigy.

Here are the results:

Band Output Current
10m 30.3W 4.9A
12m 26.0W 6.2A
15m 27.2W 6.7A
17m 28.4W 7.2A
20m 45.9W 8.5A
30m 56.6W 9.0A
40m 50.3W 8.7A
60m 53.6W 8.3A
80m 63.6W 8.1A
160m 64.6W 8.0A

Needless to say my expectations for this very small, lightweight and rugged amplifier were greatly exceeded. The average across these 10 bands was 47 Watts of output. I know I won't have a steady 13.8 volt Astron power supply in my pack like I had with this test but with a lightweight lithium battery you can't go wrong.

Good things come in small packages! You can read more about this amp at
(I am not affiliated with other than being a satisfied customer.)

David A. Rutledge

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