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On a side note, on these hb amps,? I design the PI net in software...but I also use a LOT lower loaded Q.? (I gave up on the PI-L...major pita.? The PI-L config uses a LOT more L1 coil between the

Sounds about right. I will measure the IMD just for fun. For 10 meters it has a fixed tune cap so you only need to set the load to about 80. If you leave that alone, You can switch 10, 15,20,40 and 80

Clark, u are correct. The 374A has 160m...the 374 does not have 160m.? And on all of em, 160+10m is strictly manual tune. Glen, AE0Q ( who used to work for alpha....(and still answers their tech

As per the manual, your amp has a limit of 1kw INPUT for constant carrier or data modes. This translates to about 500 to 600W MAX. Running this amp on FT8 At 1k output is way way way above its design

Dead right, Alek. Hence the need for a YC156 amp !! Sent: Monday, March 4, 2024 5:54 PM To: [email protected] Subject: Re: [ham-amplifiers] High Temperature in Toroid of the PI-L network (Alpha

The 374A model does have 160. I have one here. I think the NON A model did not? However, They don't allow bandpass on 160. Just manual tune. I just repaired a 76CA and a 374A. I got them from a

That Alpha? 78 is interesting.? It appears to be an updated version of the older Alpha 374A.? ? Both had the option of either...'manual tune' ..... or? 'bandpass? mode'.? The...'bandpass mode'

Mine went from Hammond to DigiKey and then was shipped to me.

Well, that's no surprise. Don't run any more than 30% of maximum power in FT8 mode. That goes for radios and amplifiers. Stick to that and you'll never have a problem. 73, Alek VK6APK.

I just read through the entire manual. https://www.alpharfsystems.com/wp-content/uploads/2016/05/Alpha_78_Operating_and_Technical_Manual.pdf On data modes, like FT-8, that amplifier HAS to be operated

FT8 is a 100% duty cycle mode and at some point depending on wire size and physical size of the toroid it will at some point overheat. ?It it overheats too much the permeability of the core itself

Hi, Last week my Alpha 78 stopped working. I found the windings of the L5 was burned. I rewinded the toroid with new wires. Now, it is working. I checked the temperature after transmitting on 80

DigiKey sells the Hammond transformers, but does not stock them. They are ordered through DigiKey, and then shipped direct from Hammond. First, you look up the listing of Peter Dahl transformers:

Agree 100% Jim. I've got some nice little 3-amp FWB rectifiers. I'll toss the single diode and stick an FWB in, along with a fresh cap. -- 73, ~Alan

It's two boards. One for control & the other for bias voltages. http://www.ifwtech.co.uk/g3sek/

Are there more than one set of boards: i.e., are you selling multiple sets of boards for multiple amplifiers?? Or is this just one amplifier-set of boards? TNX, Steve K0XP

Boards are 95% assembled and configured for 4-250A tubes. If you plan on using different tetrode tubes, you'll need to do the math outlined in the printed manual I'm including. Includes R14 wire-wound

I bought one last year from? them,10 week wait and total cost was about 1K.? ?? 73s Bob W5RG

How do you find the Peter Dahl transformer listings on Digi Key? Or any US seller? Trying to find the price to decide on a tube switch for an Alpha 76PA 3-tube amp. 73, Dave, w6de Sent: 1 March, 2024

I would toss the 1/2 wave rectifier......and replace it with a FWB.? ? Then bond the negative to the chassis.? ?A 1/2 wave rectifier is abt the stupidest thing I have ever seen.? You end up with