I use an HF Packer on many of my activations and find it excellent. The kits seem to be sold at near cost-price and are not always available. However, K5OOR has jusr announced that they are in stock again. See:
With the current exchange rate they are excellent value-for-money in my view. A really neat feature is the internal 12-24v SMPS which means the amplifier runs at full output power right down to the lowest voltage of a SLAB.
My amplifier delivers 35-45W on most bands although the output drops off significantly above 21MHz.
Pros: Very comprehensive instructions. Very compact & light, specifically designed for backpacking. Bags of output with the '817 set to 1 watt. Proper low pass filters (unlike certain Italian CB amps).
Cons: A bit under-biased for SSB as standard. Not too worried, I’ll keep it low as I use it mostly on CW anyway. It’s not like I get loads of complaints…
I’ve fitted a jack socket to mine and made a lead which plugs into the ‘ACC’ socket on the '817 to hard switch the T/R relay in the linear, saves waiting a few seconds for the RF vox to switch back to Rx.
I run it off a 7.2 A/Hr S.L.A.B. - free from a scrap UPS. Have used it mobile in the car too.
Cons: A bit under-biased for SSB as standard. Not too worried, I’ll
keep it low as I use it mostly on CW anyway. It’s not like I get loads
of complaints…
I agree completely. The designer disagrees however! I had a curious exchange of emails with another user who provided spectrum analyser plots showing the distortion products but who refused to believe that they were significant - even though some were less than 20dB down.
There is one quite decent ready made PA for the 817 available from China. It uses decent Motorola FETS and is rated above 40W on all HF bands. It lists at $195 including free (slow) shipping.
That works out at about £155 including VAT and PO handling costs. ($1.6 to £1)
That sounds interesting but the problem with a lot of the cheaper HF amps is the quality/efficiency of the Low Pass Filtering.
While the P.A. might be good and it sounds fine on the air are the harmonics sufficiently suppressed?
What is needed is a proper test that measures the harmonic suppression.
If you compare the internal photo on their website with a comparable photo of a HF Projects Packer Amp it looks as if the Low Pass Filter board is a much simpler design.