[ARC5] Fwd: Your cCystal Replacement Experience

[David Stinson]

P.S. The netcom.com links here are long dead.
I'll try to update if anyone cares.

On 11/20/2021 2:05 PM, David Stinson wrote:
>
> Wayne kindly sent me this, which I posted back
> in 2015 when I first started working with these.
> Hope it's helpful.  2015- don't time fly?
> Dave AB5S
>
> -------- Forwarded Message --------
> Subject: 	Your cCystal Replacement Experience
> Date: 	Sat, 20 Nov 2021 19:38:21 +0000
> From: 	releazer at earthlink.net
> Reply-To: 	releazer at earthlink.net
> To: 	arc5 at ix.netcom.com
>
>
>
> Today's Topics:
>
>    1. SCR-274N VHF:  More on Using Programmable Oscillators.
>       (David Stinson)
>    2. Re: SCR-274N VHF:  More on Using Programmable Oscillators.
>       (David Stinson)
>    3. P.S.  Programmable Oscillators. (David Stinson)
>    4. Re: P.S.  Programmable Oscillators. (J Mcvey)
>    5. Power Supplies, DC-DC inverters & co (Leslie Smith)
>    6. Re: P.S.  Programmable Oscillators. (David Stinson)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Sat, 26 Sep 2015 15:06:48 -0500
> From: "David Stinson"
> To: ,,"ARC-5"
>
> Subject: [ARC5] SCR-274N VHF:  More on Using Programmable Oscillators.
> Message-ID:
> Content-Type: text/plain; format=flowed; charset="iso-8859-1";
> reply-type=original
>
> On subbing programmable oscillators for crystals:
>
> While a real crystal from a reputable supplier like Bry,
> AF4K, is always preferable, freqs are not always available
> and multiple custom crystals are for people with more
> money than I have. This may give you an option.
>
> Most of you know I had success replacing unavailable
> crystals in the 4-channel "ARC-5" VHF
> receiver using programmable oscillators.
> Was listening to aircraft on 122.8 UNICOM
> carrying jumpers just this lovely morning.
> The only problem with this 72-year-old receiver
> is keeping the relays working.
>
> Respectfully- I've heard all the arguments about noise
> and jitter, etc. These oscillators are much better than
> the ones made just a few years ago. I've used them
> on-the-air at fundimental and to feed multipliers.
> I have had no serious issues. Works with just about
> any Pentode-based crystal osc.
> Not enough drive for Triodes like the Pierce.
>
> http://home.netcom.com/~arc5/ARC5/ProgOsc/ProgOsc.jpg 
> (http://home.netcom.com/~arc5/ARC5/ProgOsc/ProgOsc.jpg)
>
> I finally got to work on the BC-950 transmitter.
> $4 Epson CMOS oscillators at the crystal frequencies
> (F/18) for 122.8 and 146.52 MC. Powered at 6.25V
> via one of those inexpensive (2-3 bucks) little "buck"
> DC-DC converters feed by the 24V A+ buss.
>
> http://home.netcom.com/~arc5/ARC5/ProgOsc/progosc1.jpg 
> (http://home.netcom.com/~arc5/ARC5/ProgOsc/progosc1.jpg)
> http://home.netcom.com/~arc5/ARC5/ProgOsc/progosc3.jpg 
> (http://home.netcom.com/~arc5/ARC5/ProgOsc/progosc3.jpg)
>
> Mounted that with some hefty double-sided tape.
> The set works spendidly.
> Service monitor says the carriers are on 122,7997
> and 146.5200 and are clean.
>
> http://home.netcom.com/~arc5/ARC5/ProgOsc/progosc2.jpg 
> (http://home.netcom.com/~arc5/ARC5/ProgOsc/progosc2.jpg)
>
> I even made a nice contact- Don't ask.
> I'm tickled to pieces.
>
> GL OM ES 73 DE Dave AB5S
>
>
> ------------------------------
>
> Message: 2
> Date: Sat, 26 Sep 201520:24:30 -0500
> From: "David Stinson"
> To: "ARC-5"
> Subject: Re: [ARC5] SCR-274N VHF:  More on Using Programmable
> Oscillators.
> Message-ID:
> Content-Type: text/plain; format=flowed; charset="iso-8859-1";
> reply-type=response
>
> A couple of folks asked for more info on the chips.
>
> I like to use the Epson 8002 series, tri-state.
> There are many alternatives. Spec sheet:
>
> http://home.netcom.com/~arc5/ARC5/ProgOsc/SG8002DB.pdf 
> (http://home.netcom.com/~arc5/ARC5/ProgOsc/SG8002DB.pdf)
>
> This time, I used the 8-pins, speced for 85 degrees C.
> This is Digikey's listing. Cheap at $4 each.
> Takes a couple of days via USPS First Class to get them.
>
> http://tinyurl.com/nu3o2h6 (http://tinyurl.com/nu3o2h6)
>
> On the page before confirming the order, at the bottom left,
> you can enter "notes" for the order. This is where you
> tell them the freqs you want, in Mhz. They don't know KC.
>
> Cost comparison.
> Cost of Custom Crystal: $45
> Cost of completed DDS VFO kit:  $150
> Cost of Programmable Osc substitute:  about $7
>
> Next step in this project:
> A simple FM detector for the receiver using an NE612 IC.
>
> 73 DE Dave AB5S
>
>
> ------------------------------
>
>
>
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