[Amps] Ameritron AL-800

[Douglas L]

You’re right about the fairly rapid advances in technology. Back in the 1970’s I was an assistant engineer at WELI radio, a 5 KW AM station in New Haven, Connecticut.
Our main transmitter was a 1955 vintage RCA BTA-5H. It took up three 60” by 48” racks, one for the driver and RF output, one for the modulator and one for the power supply.
  I recommended a then new design Nautel all solid state transmitter. Despite using 5 (I think) one kw modules, the whole transmitter was in one rack.
  However the chief was suspicious of an all solid state rig and went with a Harris MW-5, that only used one tube which I believe was a 4CX10,000a.
  It’s been almost 50 years and I think that station still has the Harris as a backup transmitter.
Doug/WA1TUT

> On Dec 9, 2025, at 1:00 PM, Steve Thompson via Amps <amps at contesting.com> wrote:
> 
> Unfortunately, plain text doesn't convey the tongue-in-cheek and intended humour of my comment (prompted by not long having received the info. about the new LDMOS part). Well cared for, tubes will often outlive their owners; my 60 yr old 813s probably will.
> 
> Nevertheless, a single transistor rated at 3-4kW output is an intriguing prospect and would have been the stuff of science fiction when I started out in RF design.
> 
> Steve G8GSQ
> 
>> On 09/12/2025 15:34, Steve Bookout, NR4M wrote:
>> Have you given any thought to converting to some of the Russian tubes.
>> Would justhave to be an easier rebuild than converting to LDMOSFET’s. And, when I last looked those tubes are still less expensive than ‘Merican alternatives.
>> Steve NR4M
>> Sent from my iPhone
>>>> On Dec 9, 2025, at 6:03 AM, Douglas L via Amps <amps at contesting.com> wrote:
>>> 
>>> I wouldn’t say that using an LDMOSFET is a retrofit.
>>> It would basically mean building an entirely different amplifier with a different power supply, different input and output networks, etc.
>>> 
>>>> On Dec 9, 2025, at 5:32 AM, Steve Thompson via Amps <amps at contesting.com> wrote:
>>>> 
>>>> https://www.ampleon.com/products/extremely-rugged/75-v/ART4K0FX.html
>>>> 
>>>> But not the easiest retrofit 🙂
>>>> 
>>>> Steve G8GSQ
>>>> 
>>>>>> On 09/12/2025 08:37, Douglas L via Amps wrote:
>>>>> Has anyone created a work around to replace the 3CX800A7 tubes in the AL-800, the AL800H, Alpha, Ten-Tec and other amps that used this tube?
>>>>> Eimac versions are greater than $1500 and the Chinese subs, last I looked, were pushing toward $1000/tube. Machlett, Penta and the like are simply rebranded Chinese tubes.
>>>>> Medical pulls have largely dried up with MRI and other machines going solid state.
>>>>> Thus the tube pricing has gotten ridiculous.
>>>>>  Perhaps the only answer is going to solid state amps?
>>>>> 73,
>>>>> DougWA1TUT
>>>>> _______________________________________________
>>>>> Amps mailing list
>>>>> Amps at contesting.com
>>>>> http://lists.contesting.com/mailman/listinfo/amps
>>>> 
>>>> 
>>>> _______________________________________________
>>>> Amps mailing list
>>>> Amps at contesting.com
>>>> http://lists.contesting.com/mailman/listinfo/amps
>>> 
>>> 
>>> _______________________________________________
>>> Amps mailing list
>>> Amps at contesting.com
>>> http://lists.contesting.com/mailman/listinfo/amps
> 
> 
> _______________________________________________
> Amps mailing list
> Amps at contesting.com
> http://lists.contesting.com/mailman/listinfo/amps