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DAVE [BITX20] RF Preamp - Attenuator
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Woody
Hi Dave,
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I think all (more than?) you want to know can be found on my web site,? www.albe24.com Need to scroll down and click on the Amateur Radio section, then to the uBitX. The thumbnail image is a link to a ZIP file with the most pertinent information on my build.? It is about a 4 meg file. The direct link is:? www.albe24.com/kz4akubitx.zip Hope this helps.? I think everything is now accurate!? Let me know if more info needed. Woody -------------------------------------- On 12/17/2018 16:06, Dave Space wrote:
Hi do you have the files for the RF pre-am and the agc? |
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Woody
Thanks!
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Be advised that my AGC amp leaves something to be desired.? It works, but needs refinement.? Attack can be slow and it can pump on really strong signals.? Sure wish I had some old Plessey SL621 AGC ICs.? Used one "back in the day"...? They were really great for this sort of application, but they are no longer available. __W__ On 12/18/2018 1:48, Dave Space wrote:
On Mon, Dec 17, 2018 at 03:28 PM, Woody wrote: |
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Don't know if they are authentic but you can get them (kind of expensive $6 bucks apiece on Ebay). Also from Kynix for $7.25.
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Mike K5ESS -----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Woody Sent: Monday, December 17, 2018 8:08 PM To: [email protected] Subject: Re: DAVE [BITX20] RF Preamp - Attenuator Thanks! Be advised that my AGC amp leaves something to be desired. It works, but needs refinement. Attack can be slow and it can pump on really strong signals. Sure wish I had some old Plessey SL621 AGC ICs. Used one "back in the day"... They were really great for this sort of application, but they are no longer available. __W__ On 12/18/2018 1:48, Dave Space wrote: On Mon, Dec 17, 2018 at 03:28 PM, Woody wrote: |
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Woody
Thanks for the lead....? Although not too cheap, sure not $250!? Will check it out.? Found a datasheet ( ). It is a pretty bad scan, but maybe enough.
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Woody - KZ4AK On 12/18/2018 4:14, K5ESS wrote:
Don't know if they are authentic but you can get them (kind of expensive $6 bucks apiece on Ebay). Also from Kynix for $7.25. |
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Woody
Began to order and discovered that they want $35 shipping from Hong Kong.? Trying to decide if I want one that bad.?? ...But thanks.
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Woody On 12/18/2018 4:14, K5ESS wrote:
Don't know if they are authentic but you can get them (kind of expensive $6 bucks apiece on Ebay). Also from Kynix for $7.25. |
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Woody
Have used 8307s in several projects. It is a log amp with rather high freq capability which can be tamed, but it does not offer the attack / decay features of the SL621.?? Still, a possibiliity.
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Woody On 12/18/2018 15:07, BruceN wrote:
Why not take a look at the AD8307.? Seems to be comparable to the SL621.? Different package though. |
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Ebay offers shipping of $2 or $3 from China.
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Mike K5ESS -----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Woody Sent: Tuesday, December 18, 2018 9:45 AM To: [email protected] Subject: Re: DAVE [BITX20] RF Preamp - Attenuator Began to order and discovered that they want $35 shipping from Hong Kong. Trying to decide if I want one that bad. ...But thanks. Woody On 12/18/2018 4:14, K5ESS wrote: Don't know if they are authentic but you can get them (kind of expensive $6 bucks apiece on Ebay). Also from Kynix for $7.25. |
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i suppose? ebay is offering 10pcs? smd version at less than $3 and free shipping. On Tue, Dec 18, 2018 at 11:30 PM K5ESS <k5ess.nothdurft@...> wrote: Ebay offers shipping of $2 or $3 from China. |
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Woody
Thanks Mike...? Found 1621s on ebay for <$6 and total of $5 for shipping.? Ordered 3.? Might take a long time for delivery.? I didn't spring for the $30-$35 shipping for three 8-pin dips!
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Woody On 12/18/2018 18:00, K5ESS wrote:
Ebay offers shipping of $2 or $3 from China. |
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Geoff G3NPI
¿ªÔÆÌåÓýAt a quick glance, the input to the FET at the top left is earthed. Try taking it straight to the input and delete the resistor. ? Geoff? G3NPI ? Sent from for Windows 10 ? From: Dave Space
Sent: Thursday, December 20, 2018 1:30 AM To: [email protected] Subject: Re: DAVE [BITX20] RF Preamp - Attenuator ? I tried to model the agc on multsim but not sure I did it right the signal doesn't appear to come out correctly ? |
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