[minima] Re: A linear for the Minima
- From: Ashhar Farhan <farhanbox@xxxxxxxxx>
- To: minima@xxxxxxxxxxxxx
- Date: Mon, 24 Feb 2014 10:39:12 +0530
mac and gang,
i am usually on the run and i reply from my phone. it makes for very short,
curt emails. sorry for the bother, but i think it is better to send out a
short reply instead of no reply at all!
- f
On Mon, Feb 24, 2014 at 10:30 AM, Mac A. Cody <maccody@xxxxxxx> wrote:
> Farhan,
>
> Thanks for both replies. I fully understand now.
>
> 73,
>
> Mac AE5PH
>
>
> On 02/23/2014 09:51 PM, Ashhar Farhan wrote:
>
> 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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