[minima] Re: A linear for the Minima
- From: Ashhar Farhan <farhanbox@xxxxxxxxx>
- To: minima@xxxxxxxxxxxxx
- Date: Mon, 24 Feb 2014 09:21:02 +0530
Mac,
A. I meant that you can provide +24v to the FET instead of 12 volts. This
is the easiest way to get more more. I would imagine that you will get
about 10-15 watts of power. +24v smps (switching mode power supply) are
available quite cheaply on the net. Here's one that I just located :
http://www.aliexpress.com/item/Original-MeanWell-50W-5V-24V-12V-Triple-Output-Switching-Power-Supply-NET-50D-UL-CB-SMPS/949336685.html
C. By a boot, I meant an external linear amplifier. Search for WA2EBY's
amplifier. Highly recommended.
- f
On Mon, Feb 24, 2014 at 9:03 AM, Mac A. Cody <maccody@xxxxxxx> wrote:
> Farhan,
>
> Thanks for your response. I don't understand a few things, though:
>
> A. What are "24V smps"? Or do you mean "24V amps"?
>
> C. What do you mean by "an external boot"?
>
> I do not understand exactly what you mean by "on 7 and 3.5 you
> could expect far greater power". Do you mean 7 MHz and 3.5 MHz?
>
> 73,
>
> Mac AE5PH
>
>
>
> On 02/23/2014 07:02 PM, farhanbox@xxxxxxxxx wrote:
>
>> Mac,
>> There are several ways to 10 watts.
>> A. Just use 24V on the IRF510's drains. The 24V smps are quite cheap on
>> the ebay, etc.
>> B. Use an RD16HHF10 inplace of the ol' IRF510. You will have to use a
>> trifilar winding in the final instead of the bifilar one.
>> C. Use an external boot(my current solution).
>>
>> This amp is sort of non-scalable to higher power because of the driver
>> chain. The amp is extremely easy to build as it is now. Being RC coupled,
>> it is unreasonable to expect more than 3-4V peak from the drivers without
>> substantial distortion. That limits how much power can be drawn from the
>> final PA.
>> Btw, on 7 and 3.5, you could expect far greater power from the current
>> configuration.
>> - f
>> Sent from BlackBerry® on Airtel
>>
>> -----Original Message-----
>> From: "Mac A. Cody" <maccody@xxxxxxx>
>> Sender: minima-bounce@xxxxxxxxxxxxx
>> Date: Sun, 23 Feb 2014 14:07:50
>> To: <minima@xxxxxxxxxxxxx>
>> Reply-To: minima@xxxxxxxxxxxxx
>> Subject: [minima] Re: A linear for the Minima
>>
>> Farhan,
>>
>> Very nice design for the amplifier! I am curious, though, what it
>> wouldtake to boost the power to ten watts, so that the Minima could
>> have a 'full gallon' for SSB QRP?
>>
>> 73,
>>
>> Mac AE5PH
>>
>> On 02/23/2014 05:34 AM, Ashhar Farhan wrote:
>>
>>> I just finished a linear amp that is entirely RC-coupled except for
>>> the power stage's output. I have built two of them and they appear to
>>> very quite stable and clean. It uses just the 2N3904s in the chain
>>> except for the power output stage.
>>>
>>> The details are here http://www.hfsignals.org/index.php/RF386
>>>
>>> It started with the a stupid question "Why can't the LM386 be used in
>>> an RF linear?"
>>>
>>> I am particulary curious to know what value should one pick for the
>>> 100 ohms in the Q4. I am quite kicked by the one-line band-switching
>>> arrangement.
>>>
>>> - farhan
>>>
>>
>>
>
>
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