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Re: 7 MHz Oscillator Ideas
JT Croteau
Thanks Jerry, that helps quite a bit. I may change out t a different
BPF design as I have no strong signals of any kind near me. I live out in the middle of the woods and don't have any neighbors. On Sat, Dec 7, 2019 at 4:48 PM Jerry Gaffke via Groups.Io <jgaffke@...> wrote:
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Re: 7 MHz Oscillator Ideas
The HiPerMite has no volume control:
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? ?? And this radio has no AGC. So AA7EE's 1k pot is also your only volume control. Jerry On Sat, Dec 7, 2019 at 12:59 PM, Jerry Gaffke wrote: The 1k pot is for RF gain in case you are dealing with very strong in-band signal, |
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Re: 7 MHz Oscillator Ideas
That AA7EE front end is fairly straightforward.
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The 1k pot is for RF gain in case you are dealing with very strong in-band signal, the SA612 doesn't have a whole lot of dynamic range. The tuned bandpass filter that follows the pot prevents strong out-of-band signals from swamping the SA612, perhaps that 50kW AM broadcast station on the other side of town. It also prevents harmonics of the desired frequency from sneaking through to the audio. From the pot, the signal goes into an impedance matching transformer, the output winding of the transformer is parallel tuned with 50p+47p That first parallel tuned circuit is lightly coupled via 10p into a second very similar parallel tuned circuit, the light coupling prevents the two of them from acting as one big tuned circuit at one quarter the resonant frequency. The 10p also provides DC isolation, note that pin 2 of the SA612 does not want to be at DC ground. He calls out a NE602, any genuine part marked "NE" would have to be pretty old. These days NXP makes it, and calls it the SA612. NXP will also sell you an SA602 if you insist, but it's exactly the same part. There have also been "new and improved" A variants. But I don't believe there has been a significant difference between any of these parts for several decades. The diode tuning should be plenty stable for tuning across a few khz of 40m CW. Add a cap in parallel with the coil till you hit the desired frequency, adjust the 1000p cap till you have the desired 15khz range, If not stable enough, unhook the diode, see if it remains unstable. If not, then the neighboring caps and/or coil are the problem. If the diode proves too unstable, make sure your "8vReg" is properly regulated. NPO caps are very cheap and stable. Random caps from your junkbox will give random results. Jerry? On Sat, Dec 7, 2019 at 08:47 AM, JT Croteau wrote:
I've been thinking of taking AA7EE's approach at using NM0S's |
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Re: 7 MHz Oscillator Ideas
JT Croteau
I've been thinking of taking AA7EE's approach at using NM0S's
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HiPerMite as the audio chain. I don't fully understand his use of a tuned BPF, my lack of experience is showing here. AA7EE Rugster: On Sat, Dec 7, 2019 at 10:10 AM W0PWE <j.b.hall@...> wrote:
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Re: 7 MHz Oscillator Ideas
Rob
¿ªÔÆÌåÓý
I used a 7.16 mHz ceramic resonator with great success.
I had those resonators left over from the VK3YE regen projects.
On 12/07/2019 10:10 AM, JT Croteau
wrote:
Hi folks, I'd like to build a simple NE612/LM386 receiver to cover from roughly 7.028 to 7.042. I'm wondering what I should use for the oscillator. I've been poking around on google but it is making my head spin. Minimal drift would be ideal as I'd like to park it on 7040 or 7030 for a few hours just to monitor. Times like this I wish I still had some of my Doug Demaw books. Thanks |
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Re: 7 MHz Oscillator Ideas - good enough
JT,
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This is exactly how I used my old Ramsey kit back in the early '90s.? Had it next to my bed. It was the same NE602/LM386 design. An LC osc using the NE602 internal should work fine. A varicap (actually any diode should give your desired range) is nice and mechanically stable. The Ramsey kit made the mistake of not voltage regulating the varicap, using a 9V battery, there was a continuous small drift due to battery voltage drop. If you use a variable C or L instead of the varicap, the NE602 has internal voltage regulation, or use a stable supply, not a 9V battery. GL and 73, Gary WB6OGD On 12/7/2019 7:44 AM, JT Croteau wrote:
Hi Bill, |
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Re: 7 MHz Oscillator Ideas
I like the receiver section of the SST xcvr for an application like this. It even has a simple AGC that works pretty well. You will probably need another stage of audio amplification if you want to use a speaker rather than headphones.
I deviated from the SST design a little and used the internal oscillator in the NE612 for the vfo. With two crystals in parallel (aka super VXO) and a whole lot of experimentation with various inductors I got a tuning range of better than 25KHz. The 40m design uses 4MHz crystals in the IF and 11.046MHz in the VFO. It has been many years but seems like I used 11.059MHz crystals in mine. Another good option would be the Universal Receiver Kit from Kits and Parts.? 73 - Jerry - W0PWE |
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Re: K1SWL has done it again, the Phaser!
Dave has posted on the CWTD Group his thoughts on using a DC Receiver with the Phaser Transceiver:
"We considered interoperability between Phaser users to be an important design goal.?? That drove the design to single-sideband transmit, and we recently validated that goal with a Phaser-to-Phaser contact.? ? The use of DSB rather than SSB on receive was a simplification and a considerable one at that.? In view of the few instances where we felt this issue would arise, we elected to go forward with 'less complex' and still economical."
?73- Dave Benson, K1SWL |
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Re: 7 MHz Oscillator Ideas - good enough
JT Croteau
Hi Bill,
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CW only. I just want something to monitor 7030 and 7040 while I am smoking a pipe and reading in my single room cabin or drifting off to sleep. 73 On Sat, Dec 7, 2019 at 9:42 AM Bill Cromwell <wrcromwell@...> wrote:
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Re: 7 MHz Oscillator Ideas - good enough
Hi JT,
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What modes do you have in mind? CW and most of the digital modes are not particularly fussy about a little drift. A free running, L-C VFO should give you what you *need*. The ones I have that use vacuum tubes take a little longer - up to a half hour to settle down. A couple of the solid state oscillators settle in a few seconds. For some people, splitting hairs multiple times is a hobby. Hobbies have their own rewards. Most amateur modes do not require milliHertz precision. If you expect to work some of the super slow, deep noise modes like some of the JT stuff you better look at some of the digital VFO designs and even some of those are not "good enough". In my working life we made measurements with resolution and accuracy of a few millionths of one inch - in some cases two millionths. In my woodworking hobby that is just ridiculous:) I do hold "some" tolerances quite a bit closer than the guy who cuts pieces at Home Depot but nobody gets bragging rights for that:) At home depot the tolerances on those saws is "good enough". 'Good enough' does not mean "sloppy" or "inferior". Good luck with your fun project. Merry Christmas and... 73, Bill KU8H On 12/7/19 10:10 AM, JT Croteau wrote:
Hi folks, I'd like to build a simple NE612/LM386 receiver to cover --
bark less - wag more |
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7 MHz Oscillator Ideas
JT Croteau
Hi folks, I'd like to build a simple NE612/LM386 receiver to cover
from roughly 7.028 to 7.042. I'm wondering what I should use for the oscillator. I've been poking around on google but it is making my head spin. Minimal drift would be ideal as I'd like to park it on 7040 or 7030 for a few hours just to monitor. Times like this I wish I still had some of my Doug Demaw books. Thanks |
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Using Re-Purposing those Flat Mobile Phone Cells
From old mobile phones, I've saved several sizes of various AHr capacity cells.
If you don't have a way to make compression contact to the terminals on the top, you can solder to them. The terminals are not connected directly to the cell, they use spot-welded metal strips** to make the connections. The tiny spot welds don't quickly transfer heat from the terminals on top to the cells underneath the plastic top piece. For charging without a cell phone, I use one of the universal chargers. Specifically the one with the charge indicator on one end. This one has spring-loaded pushpins that will make contact to rough uneven surfaces like solder connections.eBay has several versions, The least expensive works fine and they will handle a wide-range of cell widths. <https://www.ebay.com/itm/Mobile-Universal-Battery-Charger-LCD-Indicator-Screen-For-Cell-Phones-1-USB-Port/112928050208?_trkparms=aid%3D1110001%26algo%3DSPLICE.SIM%26ao%3D1%26asc%3D20131231084308%26meid%3D91b72536d82e43799d94256405b46820%26pid%3D100010%26rk%3D3%26rkt%3D12%26mehot%3Dpp%26sd%3D121883657151%26itm%3D112928050208%26pmt%3D0%26noa%3D1%26pg%3D2047675&_trksid=p2047675.c100010.m2109> I'm using one of the re-purposed cells in my SMT keyer and after a couple of years now the voltage is still close to the charge nominal 4.2 V. ** I've taken them apart for a look-see. -- Chuck, W5USJ (ex K2OFN) Point, Rains Co, TX? EM22cv |
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Re: K1SWL has done it again, the Phaser!
Eric KE6US
¿ªÔÆÌåÓýVery similar to the PSKs. When I first worked JT65, I considered converting my PSK-20 to JT65. In the end, I couldn't bear to cut up such neat little rig. I'm glad I didn't. JT modes remind me of stamp collecting only not as personal. They had one thing going for them, though. JT65 and JT9 are the only modes I've ever used where I actually worked the guy who invented them. I'm old, but Morse and Vail were long gone before I was born. Eric KE6US
On 12/6/2019 9:42 AM, JT Croteau wrote:
Just like the Warbler and PSK series of days long ago, K1SWL has done it again by teaming up with N2APB to produce a phasing SSB QRP transceiver for FT8 and other digital modes. With two frequencies available and a cost of only $50 per band, we can put our DSB toys out to pasture. Kits start shipping Dec. 16th: I've ordered two thus far. N1ESE |
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Re: K1SWL has done it again, the Phaser!
JT Croteau
Thanks Ryan, I missed your write up. I'm hoping it will not be too
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difficult to modify one for 160M. On Fri, Dec 6, 2019 at 11:49 AM Ryan Flowers <geocrasher@...> wrote:
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K1SWL has done it again, the Phaser!
JT Croteau
Just like the Warbler and PSK series of days long ago, K1SWL has done
it again by teaming up with N2APB to produce a phasing SSB QRP transceiver for FT8 and other digital modes. With two frequencies available and a cost of only $50 per band, we can put our DSB toys out to pasture. Kits start shipping Dec. 16th: I've ordered two thus far. N1ESE |
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Re: NP0 Capacitors for QRP homebrew
Easy enough.
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Let's expand that range to all values from 0.0000001 F to 100000 pF. What more could you want?? ?;-) Jerry, KE7ER ?? On Mon, Dec 2, 2019 at 10:43 AM, Nick Kennedy wrote:
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Re: NP0 Capacitors for QRP homebrew
Heh yeah, they are just listing then numerically rather than by capacitance. Kind of silly, but there's a good variance in the capacitors themselves.? Ryan Flowers On Mon, Dec 2, 2019 at 10:43 AM Nick Kennedy <kennnick@...> wrote:
--
Ryan Flowers W7RLF
https://miscdotgeek.com |
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Re: NP0 Capacitors for QRP homebrew
I got an email from Amazon a couple days ago offering a capacitor assortment from 0.1 uF to 100 nF. Could we expand that range a little? 73- Nick, WA5BDU On Mon, Dec 2, 2019 at 11:54 AM John KJ4IFO via Groups.Io <svsunbow=[email protected]> wrote: |
Chuck Carpenter
Nick Kennedy
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