[Milsurplus] Fwd: Crystal Substitute

[B. Smith]

Wow, talk about using all the features of a board. The MAB crystal 
substitute is simple but brilliant. The use of 20 Turn toroid coils to 
raise the voltage is a trick going in my note book and it may solve one 
of my DDS VFO drive problems. Most hams have "Coil Phobia" and will 
avoid any project that involves coil winding but they should be able to 
do 20 turns without therapy.
Many thanks for the excellent sketch.

Q.  How long does it take for the board to come up to speed when voltage 
is applied? Is it possible to key it for CW or possibly switch back and 
forth between banks for keying?
73
K4CHE


On 7/8/2024 8:10 PM, Ron De Silva wrote:
>
> ---------- Forwarded message ---------
> From: *Ron De Silva* <rdesilva49 at gmail.com>
> Date: Sun, Jul 7, 2024, 11:30 PM
> Subject: Re: [Milsurplus] Crystal Substitute
> To: B. Smith <smithab11 at comcast.net>
>
>
> I purchased one of the new Prog Rock 2 units in April.
>
>
> I wanted to try out the unit on the latest MAB I restored.
>
> I tried a few different designs.
>
> The simplest approach works pretty well by winding a toroidal xfmr to 
> take the 3vpp output up to 16vpp in circuit ,still not as good as the 
> original 30vpp in circuit drive to PA, but not much change in output 
> level.
>
> The toroidal xfmr driving the receive mixer was fine.
>
> The prog rock has continuous output on 3 clocked outputs in each of 8 
> banks.
>
> Obviously. The TX osc running continuously wipes out the receiver.
>
> To handle switching.
>
> I programmed BANK 0 with the first receive frequency in CLOCK 0 and no 
> transmit freq in  Clock 1
>
> And programmed Bank 1 with the desired receive frequency in CLOCK 0 
> and the TRANSMIT frequency Clock 1
>
> When in transmit, I took the 1.5v on TX to turn on an opto isolator 
> and its output selects Bank1 on transmit.
>
> I made some little pc boards to hold all components and the whole 
> assembly plugs into the side by side FT243 crystal sockets.
>
> No mods were  done to the MAB except add two wires to pick up the 
> minus 6volts power from the C battery and the +1 5v from the transmit 
> tube filaments .
>
>
>
>
>
>
>
>
>
> On Sun, Jul 7, 2024, 12:15 PM B. Smith <smithab11 at comcast.net> wrote:
>
>     QRP Labs is now taking preorders on their programmable crystal
>     ProgRock2.
>     No I have not tested the new board.
>     K4CHE
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