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Everything about the VNWA internals!
What is interesting is the simplicity of the approach (ignoring the hidden
cost of the ubiquitous PC), but it ignores the multiple harmonics that come out of DDS chips. So, if you were to working at, say, 3MHz, how would youknow that you were not actually analysing responses at 6, 9, 12, 15, etc MHz? http://sdr-kits.net/DG8SAQ/VNWA/Baier_VNWA2_QEX.pdf But it does raise one question, and that is, who is fooling who about its purchase price of ooo £450, for there cannot be more than about £40 in its component costs? |
Everything about the VNWA internals!
In rec.radio.amateur.antenna gareth wrote:
What is interesting is the simplicity of the approach (ignoring the hidden cost of the ubiquitous PC), but it ignores the multiple harmonics that come out of DDS chips. So, if you were to working at, say, 3MHz, how would youknow that you were not actually analysing responses at 6, 9, 12, 15, etc MHz? http://sdr-kits.net/DG8SAQ/VNWA/Baier_VNWA2_QEX.pdf But it does raise one question, and that is, who is fooling who about its purchase price of ooo ?450, for there cannot be more than about ?40 in its component costs? Assembly, test, calibration kit, expansion board, presentation storage case, cables, etc. -- Jim Pennino |
Everything about the VNWA internals!
On Tue, 29 Dec 2015 22:14:45 -0000, "gareth"
wrote: What is interesting is the simplicity of the approach (ignoring the hidden cost of the ubiquitous PC), but it ignores the multiple harmonics that come out of DDS chips. One of the nice things about DDS is the lack of harmonics and distortion. Given sufficient bits, you won't see much in the way of harmonics. If there are are any harmonics, it's treated as "distortion" which in this case means unwanted junk signals. See the section on "dynamic performance". http://www.embedded.com/design/configurable-systems/4025078/Understanding-analog-to-digital-converter-specifications SNR(dB) = (6.02*N) + 1.76 where N = number of bits So, if you have a 8 bit DDS, all the junk will be down: (6.02*8)+1.76 = 50 dB I think that's sufficient for most VNA applications. Of course, you can introduce other forms of distorition (jitter, non-linearity, clipping, symmetry, etc) errors in stages after the DDS. So, if you were to working at, say, 3MHz, how would youknow that you were not actually analysing responses at 6, 9, 12, 15, etc MHz? Ummm... That's what a spectrum analyzer is used for. http://sdr-kits.net/DG8SAQ/VNWA/Baier_VNWA2_QEX.pdf But it does raise one question, and that is, who is fooling who about its purchase price of ooo £450, for there cannot be more than about £40 in its component costs? Jim Pennino listed a good start on what's missing. If you're going to make it portable, add shock mounting, drop proof case, coax adapters, leash, etc. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
Everything about the VNWA internals!
On 12/29/2015 8:17 PM, Jeff Liebermann wrote:
On Tue, 29 Dec 2015 22:14:45 -0000, "gareth" wrote: What is interesting is the simplicity of the approach (ignoring the hidden cost of the ubiquitous PC), but it ignores the multiple harmonics that come out of DDS chips. One of the nice things about DDS is the lack of harmonics and distortion. Given sufficient bits, you won't see much in the way of harmonics. If there are are any harmonics, it's treated as "distortion" which in this case means unwanted junk signals. See the section on "dynamic performance". http://www.embedded.com/design/configurable-systems/4025078/Understanding-analog-to-digital-converter-specifications SNR(dB) = (6.02*N) + 1.76 where N = number of bits So, if you have a 8 bit DDS, all the junk will be down: (6.02*8)+1.76 = 50 dB I think that's sufficient for most VNA applications. Of course, you can introduce other forms of distorition (jitter, non-linearity, clipping, symmetry, etc) errors in stages after the DDS. The issue with noise from a DDS is that all noise is not the same. A DDS is used to produce a sine wave, preferably of a single frequency. A typical DDS has a phase accumulator word of some number of bits which establishes the accuracy of the frequency being produced. Then some or all of those bits are used to produce digital samples of the sine wave. The quantization noise of the sample produces noise which is fairly evenly spread across the spectrum, but related more to the clock rate than the carrier frequency. The quantization noise from the phase word produces noise which has significant content very close to the carrier. This noise can not be easily filtered and so is of great concern. The fewer phase word bits used (called phase truncation) to produce the sine values the greater the close in noise. For the most part you seem to be describing noise created by an ADC or DAC which is dependent on the number of bits in the sine wave sample. -- Rick |
Everything about the VNWA internals!
On Tue, 29 Dec 2015 21:20:24 -0500, rickman wrote:
On 12/29/2015 8:17 PM, Jeff Liebermann wrote: On Tue, 29 Dec 2015 22:14:45 -0000, "gareth" wrote: What is interesting is the simplicity of the approach (ignoring the hidden cost of the ubiquitous PC), but it ignores the multiple harmonics that come out of DDS chips. One of the nice things about DDS is the lack of harmonics and distortion. Given sufficient bits, you won't see much in the way of harmonics. If there are are any harmonics, it's treated as "distortion" which in this case means unwanted junk signals. See the section on "dynamic performance". http://www.embedded.com/design/configurable-systems/4025078/Understanding-analog-to-digital-converter-specifications SNR(dB) = (6.02*N) + 1.76 where N = number of bits So, if you have a 8 bit DDS, all the junk will be down: (6.02*8)+1.76 = 50 dB I think that's sufficient for most VNA applications. Of course, you can introduce other forms of distorition (jitter, non-linearity, clipping, symmetry, etc) errors in stages after the DDS. The issue with noise from a DDS is that all noise is not the same. A DDS is used to produce a sine wave, preferably of a single frequency. A typical DDS has a phase accumulator word of some number of bits which establishes the accuracy of the frequency being produced. Then some or all of those bits are used to produce digital samples of the sine wave. The quantization noise of the sample produces noise which is fairly evenly spread across the spectrum, but related more to the clock rate than the carrier frequency. The quantization noise from the phase word produces noise which has significant content very close to the carrier. This noise can not be easily filtered and so is of great concern. The fewer phase word bits used (called phase truncation) to produce the sine values the greater the close in noise. Notice that I didn't use the term "noise" anywhere in my comments. That was intentional as I was directly addressing the comments about "multiple harmonics". I didn't want to dive deep into how a DDS synthesizer works mostly because I don't understand it very well. I have a few cheap eBay DDS synthesizer boards, some grand ideas, and no time to play. For the most part you seem to be describing noise created by an ADC or DAC which is dependent on the number of bits in the sine wave sample. Exactly. Ignoring noise and jitter, if the DDS DAC has enough bits and is sufficiently linear, the harmonics will not be a problem for a VNA which does not have enough display resolution to where the noise is going to be a problem. A common DDS chip is the AD9850 which uses a 10 bit DAC and 14 bits for that phase after truncation: http://datasheet.octopart.com/AD9850BRS-Analog-Devices-datasheet-88235.pdf 10 bits puts the harmonics theoretically about -60dB down from the carrier. However, that won't happen as there are other sources of noise, errors, distortion, junk, non-linearity, etc. At about 3MHz, I recall seeing about -40dB, which became worse above 25 MHz. Argh... back to (paper)work. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
Everything about the VNWA internals!
On 12/29/2015 10:29 PM, Jeff Liebermann wrote:
On Tue, 29 Dec 2015 21:20:24 -0500, rickman wrote: On 12/29/2015 8:17 PM, Jeff Liebermann wrote: On Tue, 29 Dec 2015 22:14:45 -0000, "gareth" wrote: What is interesting is the simplicity of the approach (ignoring the hidden cost of the ubiquitous PC), but it ignores the multiple harmonics that come out of DDS chips. One of the nice things about DDS is the lack of harmonics and distortion. Given sufficient bits, you won't see much in the way of harmonics. If there are are any harmonics, it's treated as "distortion" which in this case means unwanted junk signals. See the section on "dynamic performance". http://www.embedded.com/design/configurable-systems/4025078/Understanding-analog-to-digital-converter-specifications SNR(dB) = (6.02*N) + 1.76 where N = number of bits So, if you have a 8 bit DDS, all the junk will be down: (6.02*8)+1.76 = 50 dB I think that's sufficient for most VNA applications. Of course, you can introduce other forms of distorition (jitter, non-linearity, clipping, symmetry, etc) errors in stages after the DDS. The issue with noise from a DDS is that all noise is not the same. A DDS is used to produce a sine wave, preferably of a single frequency. A typical DDS has a phase accumulator word of some number of bits which establishes the accuracy of the frequency being produced. Then some or all of those bits are used to produce digital samples of the sine wave. The quantization noise of the sample produces noise which is fairly evenly spread across the spectrum, but related more to the clock rate than the carrier frequency. The quantization noise from the phase word produces noise which has significant content very close to the carrier. This noise can not be easily filtered and so is of great concern. The fewer phase word bits used (called phase truncation) to produce the sine values the greater the close in noise. Notice that I didn't use the term "noise" anywhere in my comments. That was intentional as I was directly addressing the comments about "multiple harmonics". I didn't want to dive deep into how a DDS synthesizer works mostly because I don't understand it very well. I have a few cheap eBay DDS synthesizer boards, some grand ideas, and no time to play. You mentioned "distortion" which is the problem with a DDS. The OP's use of the term "harmonic" shows his lack of familiarity with DDS technology. It is very simple really. A step size is set by the value added to an accumulator on each clock cycle. The accumulator is allowed to wrap around. This generates a ramping value representing the phase of a vector. The number of bits used in the accumulator and phase step in conjunction with the clock rate set the frequency resolution of the ramp. The next step is to turn the phase into a sine sample. Often a lookup table is used. Since the number of entries in the table is limited this limits the phase resolution used to generate the sine sample. The number of bits in the output of the table set the resolution of the amplitude. These two resolutions generate very different noise patterns. There are other ways of generating the sine samples. One is to approximate by calculation. Calculations can use a series expansion or various trig identities. These can achieve lower values of distortion with less hardware than large table lookups. The final step, if an analog signal is needed, is the DAC conversion. A DAC introduces its own types of distortion, harmonics and noise. Nothing complex really. But there are some subtleties. For the most part you seem to be describing noise created by an ADC or DAC which is dependent on the number of bits in the sine wave sample. Exactly. Ignoring noise and jitter, if the DDS DAC has enough bits and is sufficiently linear, the harmonics will not be a problem for a VNA which does not have enough display resolution to where the noise is going to be a problem. That's like saying "if you ignore the tailpipe emissions, a diesel engine is very clean". Noise and jitter *is* the limitation of a DDS. The frequency resolution is easy to make as fine as you wish. The limitation comes in reducing the close in spurs. A common DDS chip is the AD9850 which uses a 10 bit DAC and 14 bits for that phase after truncation: http://datasheet.octopart.com/AD9850BRS-Analog-Devices-datasheet-88235.pdf 10 bits puts the harmonics theoretically about -60dB down from the carrier. However, that won't happen as there are other sources of noise, errors, distortion, junk, non-linearity, etc. At about 3MHz, I recall seeing about -40dB, which became worse above 25 MHz. For many apps, such as a lot of radio work, -60 dB is not a very good number. I seem to recall seeing radio apps where -80 would be a more respectable value. But then that was military radios so maybe -60 is just fine for amateur work. -- Rick |
Everything about the VNWA internals!
gareth wrote:
What is interesting is the simplicity of the approach (ignoring the hidden cost of the ubiquitous PC), but it ignores the multiple harmonics that come out of DDS chips. Up to about 600MHz I think the DDSen are pure enough, but above that the VNWA deliberately uses mixer products of some kind. As to how, without losing all accuracy, I afraid is beyond my understanding. And down to the genius of the inventor. So, if you were to working at, say, 3MHz, how would youknow that you were not actually analysing responses at 6, 9, 12, 15, etc MHz? The multiple spurious products around are many more than simply harmonics. But in some way the phase of the desired product is tracked(?). http://sdr-kits.net/DG8SAQ/VNWA/Baier_VNWA2_QEX.pdf But it does raise one question, and that is, who is fooling who about its purchase price of ooo £450, for there cannot be more than about £40 in its component costs? That is simply not true. In small quantities they would cost a great deal more than 450GBP, and the VNWA is not produced in very large quantities. Consider the costs of quite a complicated PCB in relatively small quantities, the USB chip is quite expensive to pay for so-called intellectual property, and requires individual licensing. The DDSs are not cheap, neither is the hardware. -- Roger Hayter |
Everything about the VNWA internals!
"gareth" wrote in message
... What is interesting is the simplicity of the approach (ignoring the hidden cost of the ubiquitous PC), but it ignores the multiple harmonics that come out of DDS chips. So, if you were to working at, say, 3MHz, how would youknow that you were not actually analysing responses at 6, 9, 12, 15, etc MHz? MEA CULPA !!!!! Sorry, but I was thinking out loud about the si570 series of chips and not about DDS chips. Ooops! |
Everything about the VNWA internals!
"gareth" wrote in message
... "gareth" wrote in message ... What is interesting is the simplicity of the approach (ignoring the hidden cost of the ubiquitous PC), but it ignores the multiple harmonics that come out of DDS chips. So, if you were to working at, say, 3MHz, how would youknow that you were not actually analysing responses at 6, 9, 12, 15, etc MHz? MEA CULPA !!!!! Sorry, but I was thinking out loud about the si570 series of chips and not about DDS chips. Ooops! The other area of befuddled thinking on my part (so many dimensions to such a project!) is that when working with a tracking generator, the signal from that generator is the only one to have to consider because it will be working in a closed, and largely shielded circuit, and that therefore the selectivity of instrumentation will not be particularly relevant. Such is the case with the VNWA, where an IF of only 1kHz at frequencies off several MHz might at first sight to invite a problem with severe image responses, but, of course, with only the one signal in consideration, there cannot be any images! Anybody out there have experience of input from the sound card via the .NET framework? Also, apart from setting up ladder crystal filters, is there any real need for us to have very narrow IF filters in our speccy-plus-trackie set-ups? |
Everything about the VNWA internals!
On 12/30/2015 6:48 AM, Roger Hayter wrote:
gareth wrote: What is interesting is the simplicity of the approach (ignoring the hidden cost of the ubiquitous PC), but it ignores the multiple harmonics that come out of DDS chips. Up to about 600MHz I think the DDSen are pure enough, but above that the VNWA deliberately uses mixer products of some kind. As to how, without losing all accuracy, I afraid is beyond my understanding. And down to the genius of the inventor. So, if you were to working at, say, 3MHz, how would youknow that you were not actually analysing responses at 6, 9, 12, 15, etc MHz? The multiple spurious products around are many more than simply harmonics. But in some way the phase of the desired product is tracked(?). http://sdr-kits.net/DG8SAQ/VNWA/Baier_VNWA2_QEX.pdf But it does raise one question, and that is, who is fooling who about its purchase price of ooo £450, for there cannot be more than about £40 in its component costs? That is simply not true. In small quantities they would cost a great deal more than 450GBP, and the VNWA is not produced in very large quantities. Consider the costs of quite a complicated PCB in relatively small quantities, the USB chip is quite expensive to pay for so-called intellectual property, and requires individual licensing. The DDSs are not cheap, neither is the hardware. I think the price is a bit high for a PCB, but 450GBP is for a tested unit in the "presention case". The driver is not just the parts cost at low volume, as that only goes up some. I estimate total parts cost of ~ $100. The problem is just as much the labor involved in turning the parts into a final product. This type of assembly is done on machines and at low volume the set up costs become a significant portion of the total costs. Then adding profit easily brings this up to 450GBP. I don't know how many of these units have been sold, but the Yahoo group has 2830 members. If only half the owners are members that is still less than 6000 units. Spread over a few years that is only 150 a month or so. Not really high volume, but a nice workable volume. -- Rick |
Everything about the VNWA internals!
"gareth" wrote in message
... But it does raise one question, and that is, who is fooling who about its purchase price of ooo £450, for there cannot be more than about £40 in its component costs? DDS modules, £8 ea SA612 £2 ea PIC processor, anything from £2 to £20 ea. Double-sided PCB for ugly-bug construction, £5 Ally die cast box £15 SMA sockets £3 ea Handful of capacitors, peanuts. Software, any self-respecting radio amateur will write his own, anyway. Considering that it is homebrewers that would be using such kit, there must be some out there with more money than sense? |
Everything about the VNWA internals!
In rec.radio.amateur.antenna gareth wrote:
"gareth" wrote in message ... But it does raise one question, and that is, who is fooling who about its purchase price of ooo ?450, for there cannot be more than about ?40 in its component costs? DDS modules, ?8 ea SA612 ?2 ea PIC processor, anything from ?2 to ?20 ea. Double-sided PCB for ugly-bug construction, ?5 Ally die cast box ?15 SMA sockets ?3 ea Handful of capacitors, peanuts. Software, any self-respecting radio amateur will write his own, anyway. Considering that it is homebrewers that would be using such kit, there must be some out there with more money than sense? So why aren't you building and selling them yourself at a cut-rate price? -- Jim Pennino |
Everything about the VNWA internals!
gareth wrote:
"gareth" wrote in message ... But it does raise one question, and that is, who is fooling who about its purchase price of ooo £450, for there cannot be more than about £40 in its component costs? DDS modules, £8 ea SA612 £2 ea PIC processor, anything from £2 to £20 ea. Double-sided PCB for ugly-bug construction, £5 If you did iit like that the circuit would be about a foot (ancient American unit) across and wouldn't work. Ally die cast box £15 SMA sockets £3 ea Handful of capacitors, peanuts. Software, any self-respecting radio amateur will write his own, anyway. Considering that it is homebrewers that would be using such kit, there must be some out there with more money than sense? -- Roger Hayter |
Everything about the VNWA internals!
Brian Reay wrote:
wrote: In rec.radio.amateur.antenna gareth wrote: "gareth" wrote in message ... But it does raise one question, and that is, who is fooling who about its purchase price of ooo ?450, for there cannot be more than about ?40 in its component costs? DDS modules, ?8 ea SA612 ?2 ea PIC processor, anything from ?2 to ?20 ea. Double-sided PCB for ugly-bug construction, ?5 Ally die cast box ?15 SMA sockets ?3 ea Handful of capacitors, peanuts. Software, any self-respecting radio amateur will write his own, anyway. Considering that it is homebrewers that would be using such kit, there must be some out there with more money than sense? So why aren't you building and selling them yourself at a cut-rate price? Gareth never actually produces anything, unless you count hot air. Don't forget shame and humiliation, he produces both of those by the lorry load. -- STC // M0TEY // twitter.com/ukradioamateur |
Everything about the VNWA internals!
|
Everything about the VNWA internals!
On Thu, 31 Dec 2015 10:25:07 +0000
"Jim GM4DHJ ..." wrote: I remember in the 70's when 3amp power supplies cost a fortune a local professional started producing them and selling to the local hams...every one blew up...didn't hear much from him after that .... Gareth McEvans? |
Everything about the VNWA internals!
On 31/12/2015 10:29, Bernie wrote:
On Thu, 31 Dec 2015 10:25:07 +0000 "Jim GM4DHJ ..." wrote: I remember in the 70's when 3amp power supplies cost a fortune a local professional started producing them and selling to the local hams...every one blew up...didn't hear much from him after that .... Gareth McEvans? naw local to Glasgow....a G8 .......professional .... -- Moderated groups kill brian's abuse No spare wheel isn't progress Dual mass flywheels...no thanks A rubber cam belt is not acceptable Cheat your way through life, join the Freemasons DIGITAL just doesn't work properly most of the time |
Everything about the VNWA internals!
On Thu, 31 Dec 2015 10:36:10 +0000
"Jim GM4DHJ ..." wrote: On 31/12/2015 10:29, Bernie wrote: On Thu, 31 Dec 2015 10:25:07 +0000 "Jim GM4DHJ ..." wrote: I remember in the 70's when 3amp power supplies cost a fortune a local professional started producing them and selling to the local hams...every one blew up...didn't hear much from him after that .... Gareth McEvans? naw local to Glasgow....a G8 .......professional .... Yeah, that's the bloke. He moved away and (after a bit of a struggle) passed the morse - I wonder where he is now... |
Everything about the VNWA internals!
"Bernie" wrote in message ... On Thu, 31 Dec 2015 10:36:10 +0000 "Jim GM4DHJ ..." wrote: On 31/12/2015 10:29, Bernie wrote: On Thu, 31 Dec 2015 10:25:07 +0000 "Jim GM4DHJ ..." wrote: I remember in the 70's when 3amp power supplies cost a fortune a local professional started producing them and selling to the local hams...every one blew up...didn't hear much from him after that .... Gareth McEvans? naw local to Glasgow....a G8 .......professional .... Yeah, that's the bloke. He moved away and (after a bit of a struggle) passed the morse - I wonder where he is now... you remember who I am talking about then? ... |
Everything about the VNWA internals!
On Thu, 31 Dec 2015 11:14:23 -0000
"Jim GM4DHJ ..." wrote: "Bernie" wrote in message ... On Thu, 31 Dec 2015 10:36:10 +0000 "Jim GM4DHJ ..." wrote: On 31/12/2015 10:29, Bernie wrote: On Thu, 31 Dec 2015 10:25:07 +0000 "Jim GM4DHJ ..." wrote: I remember in the 70's when 3amp power supplies cost a fortune a local professional started producing them and selling to the local hams...every one blew up...didn't hear much from him after that .... Gareth McEvans? naw local to Glasgow....a G8 .......professional .... Yeah, that's the bloke. He moved away and (after a bit of a struggle) passed the morse - I wonder where he is now... you remember who I am talking about then? ... GM8D something? The shame was a bit much for him, hit the bottle? Spent years trying to find a 'sympathetic' morse examiner so that he could scrape a pass? |
Everything about the VNWA internals!
Bernie wrote:
On Thu, 31 Dec 2015 11:14:23 -0000 "Jim GM4DHJ ..." wrote: "Bernie" wrote in message ... On Thu, 31 Dec 2015 10:36:10 +0000 "Jim GM4DHJ ..." wrote: On 31/12/2015 10:29, Bernie wrote: On Thu, 31 Dec 2015 10:25:07 +0000 "Jim GM4DHJ ..." wrote: I remember in the 70's when 3amp power supplies cost a fortune a local professional started producing them and selling to the local hams...every one blew up...didn't hear much from him after that .... Gareth McEvans? naw local to Glasgow....a G8 .......professional .... Yeah, that's the bloke. He moved away and (after a bit of a struggle) passed the morse - I wonder where he is now... you remember who I am talking about then? ... GM8D something? The shame was a bit much for him, hit the bottle? Spent years trying to find a 'sympathetic' morse examiner so that he could scrape a pass? Rings a bell. Did he end up having a run in with the law in the end? -- STC // M0TEY // twitter.com/ukradioamateur |
Everything about the VNWA internals!
"Roger Hayter" wrote in message
... gareth wrote: "gareth" wrote in message ... But it does raise one question, and that is, who is fooling who about its purchase price of ooo £450, for there cannot be more than about £40 in its component costs? DDS modules, £8 ea SA612 £2 ea PIC processor, anything from £2 to £20 ea. Double-sided PCB for ugly-bug construction, £5 If you did iit like that the circuit would be about a foot (ancient American unit) across and wouldn't work. Sorry, Grandpa, but the numbers above do not refer to valves (tubes to the Yanks) such as the 807, or, in your own case, bearing in mind your 50-year-old second class Class B licence, such as the QQV03-20A or 4CX250B. Ugly bug construction requires only a little more space than the devices themselves. |
Everything about the VNWA internals!
gareth wrote:
"Roger Hayter" wrote in message ... gareth wrote: "gareth" wrote in message ... But it does raise one question, and that is, who is fooling who about its purchase price of ooo £450, for there cannot be more than about £40 in its component costs? DDS modules, £8 ea SA612 £2 ea PIC processor, anything from £2 to £20 ea. Double-sided PCB for ugly-bug construction, £5 If you did iit like that the circuit would be about a foot (ancient American unit) across and wouldn't work. Sorry, Grandpa, but the numbers above do not refer to valves (tubes to the Yanks) such as the 807, or, in your own case, bearing in mind your 50-year-old second class Class B licence, such as the QQV03-20A or 4CX250B. Ugly bug construction requires only a little more space than the devices themselves. Well I bow to your superior skills. I have never seen 'dead bug' construction with SMD passives in large numbers, and four sided IC packages with sub -millimeter pin spacing. I found just hand-soldering the DDSs to the multi-layer circuit board sufficient of a challenge! -- Roger Hayter |
Everything about the VNWA internals!
On Thu, 31 Dec 2015 20:28:12 -0000
"gareth" wrote: "Roger Hayter" wrote in message ... gareth wrote: "gareth" wrote in message ... But it does raise one question, and that is, who is fooling who about its purchase price of ooo £450, for there cannot be more than about £40 in its component costs? DDS modules, £8 ea SA612 £2 ea PIC processor, anything from £2 to £20 ea. Double-sided PCB for ugly-bug construction, £5 If you did iit like that the circuit would be about a foot (ancient American unit) across and wouldn't work. Sorry, Grandpa, but the numbers above do not refer to valves (tubes to the Yanks) such as the 807, or, in your own case, bearing in mind your 50-year-old second class Class B licence, such as the QQV03-20A or 4CX250B. Ugly bug construction requires only a little more space than the devices themselves. I'd never really understood the depths of your idiocy before - thanks for the clarification, Gareth! happy new year! |
Everything about the VNWA internals!
In rec.radio.amateur.antenna gareth wrote:
"Roger Hayter" wrote in message ... gareth wrote: "gareth" wrote in message ... But it does raise one question, and that is, who is fooling who about its purchase price of ooo ?450, for there cannot be more than about ?40 in its component costs? DDS modules, ?8 ea SA612 ?2 ea PIC processor, anything from ?2 to ?20 ea. Double-sided PCB for ugly-bug construction, ?5 If you did iit like that the circuit would be about a foot (ancient American unit) across and wouldn't work. Sorry, Grandpa, but the numbers above do not refer to valves (tubes to the Yanks) such as the 807, or, in your own case, bearing in mind your 50-year-old second class Class B licence, such as the QQV03-20A or 4CX250B. Ugly bug construction requires only a little more space than the devices themselves. Not when the majority of devices are SMD. -- Jim Pennino |
Everything about the VNWA internals!
On 31/12/2015 21:20, Roger Hayter wrote:
gareth wrote: Ugly bug construction requires only a little more space than the devices themselves. Well I bow to your superior skills. I have never seen 'dead bug' construction with SMD passives in large numbers, and four sided IC packages with sub -millimeter pin spacing. I found just hand-soldering the DDSs to the multi-layer circuit board sufficient of a challenge! Not much good when you need low inductance or low cap. circuitry either. Evans is simply demonstrating his lack of practical experience. |
Everything about the VNWA internals!
"Roger Hayter" wrote in message
... Well I bow to your superior skills. Well, passing the 12WPM Morse test shows that I do have the right moral fibre of true dedication to the pursuit of amateur radio, unlike those who whinged about it for 30+ years and then went for a test and a licence targetted at 5-year-olds. But, enough; rise off your knees! |
Everything about the VNWA internals!
In rec.radio.amateur.antenna gareth wrote:
"Roger Hayter" wrote in message ... Well I bow to your superior skills. Well, passing the 12WPM Morse test shows that I do have the right moral fibre Nope, just shows you are can be trained in simple skills. -- Jim Pennino |
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