[minima] Re: Today = JBoT
- From: <jerry@xxxxxxxxxxxxxxxx>
- To: minima@xxxxxxxxxxxxx
- Date: Sat, 01 Feb 2014 01:44:04 -0700
Now you guys are talking my history. My first "Big" amp in 1955 was a
pair of 807's driven by a 6V6. Built on a cardboard cigar box and lined
on the inside with copper roof flashing. The original ugly construction.
Salvaged parts from TV sets and junk radios, when you dipped the plates
of the 807's they would glow bright red when out of resonance and cool
down when tuned. You could light up a flouresent light bulb a foot away
from the transmitter. And when I was 'on the air" there was no watching
TV unless you had a high pass filter on your TV. Ah, those were the
days. Jerry K5LRU
-------- Original Message --------
Subject: [minima] Re: Today = JBoT
From: Sandeep Lohia <sandeeplohia12@xxxxxxxxx>
Date: Sat, February 01, 2014 1:25 am
To: minima@xxxxxxxxxxxxx
As to run them on battery, & for others who missed :
" it is best that you treat the all-band HF linear as a separate
project. Add
the driver and pre-drivers to it too, so it takes 1mW in and gives
whatever
your target power is.
so now once you are done with the linear, you
won't have to rebuild it again and again for each of the future rigs.
here is a rhetorical q. why transistors? why not one or two 807s or
1625s?
their filaments can still operate out of 12v supply, a simple {*inverter
made
out of two 2N3055s driving a 12-0-12 transformer} in reverse can provide
you
with juice to power their anodes. They will give you unfailing, very
stable
power of up to 50 watts (a single 6146B can give you up to 70 watts).
They
will almost never blow up and they will work on the first try.
the voltages are very bad. but no, they wont kill
you unless you want to die of them willingly.
if u use a pair of 6.3v filament valves, you can attach them in series
and
power them from {*12vdc}. alternatively, you can attach two 220-v to
6-0-6
transformers back to back, rectify the HV AC coming of the second
transformer and tap the 12 ac between the transformers for filament
power.
this is engineering folks,
on the plus side, the valve amp is usually rock stable, capable of
matching
with wide varieties of loads, and it will give you years of service with
its warm glow for a few more millamps on the filaments."
COURTESY : Ashhar Farhan
On 01/02/2014, pakdeDar <pakdedarmantaoye@xxxxxxxxx> wrote:
> And the final dimension - weight - dc power consumption - heat - etc I think
> should be carefully considered according to the spirit of " Minima "...
> What's your comment Farhan Sir ?
>
> Sudarmanta
> YC1DCN
>
> Kaspa-kaspaanlayauw ®
>
> -----Original Message-----
> From: farhanbox@xxxxxxxxx
> Sender: minima-bounce@xxxxxxxxxxxxx
> Date: Sat, 1 Feb 2014 05:56:34
> To: <minima@xxxxxxxxxxxxx>
> Reply-To: minima@xxxxxxxxxxxxx
> Subject: [minima] Re: Today = JBoT
>
> Tubes are interesting. I play with them all the time. But they need
> components apart from the tubes themselves that are very hard to source and
> ship.
> - f
> Sent from BlackBerry® on Airtel
>
> -----Original Message-----
> From: Sandeep Lohia <sandeeplohia12@xxxxxxxxx>
> Sender: minima-bounce@xxxxxxxxxxxxx
> Date: Sat, 1 Feb 2014 11:02:52
> To: <minima@xxxxxxxxxxxxx>
> Reply-To: minima@xxxxxxxxxxxxx
> Subject: [minima] Re: Today = JBoT
>
> Guru!
>
> We can run them on battery power too...
> I will forward U 'HOW TO' an innovate idea from Farhan, (in previous
> group discussion)...
> & I brought them after inspired by Farhan only :)
>
> Regards -Sandeep
>
> On 01/02/2014, gurudatta panda <gurudattabam@xxxxxxxxx> wrote:
>> If SWR and filtering is a problem, we may opt for Tube Amp, I will
>> suggest
>> for a 6146 Tube, AA8V design. Only con is you can not run them on battery
>> power.
>> Regards
>> Gurudatta
>>
>>
>> On Sat, Feb 1, 2014 at 2:00 AM, Mark G0MGX <mark.g0mgx@xxxxxxxxx> wrote:
>>
>>> Hi Farhan
>>>
>>> That's exactly what I built from the link you sent to the group before
>>> before:
>>>
>>> http://www.hfsignals.org/index.php/File:Qrp-linear.png
>>>
>>> Mine is using 2N3053s (given free by GQRP club!)
>>>
>>> M
>>>
>>>
>>>
>>> On 31/01/2014 19:13, Ashhar Farhan wrote:
>>>
>>> this is what i have used. it works quite well. except that:
>>> 1. the 2N2219s that I used blow quite easily when operating under hihg
>>> SWR
>>> 2. the driver has inordinately high current.
>>> - f
>>>
>>>
>>> On Fri, Jan 31, 2014 at 11:54 PM, Mark G0MGX <mark.g0mgx@xxxxxxxxx>
>>> wrote:
>>>
>>>> Here's my musings on building the JBoT version Farhan suggested as the
>>>> linear for Minima:
>>>>
>>>> http://g0mgx.blogspot.co.uk/2014/01/jbot-linear-for-minima.html
>>>>
>>>> Mark
>>>> G0MGX
>>>>
>>>>
>>>
>>>
>>
>>
>> --
>> *Thanks & Regards*
>>
>> *Gurudatta Panda*
>> *Jr. Site Engineer*
>> *R.V.N.L. / KDJR*
>>
>> *Mob : +91 9777447844 (Work)*
>> * +91 9778238593 (Home)*
>>
>
>
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