XTAL AND DSP simply is the best design
Locked
 
|
You look at the TS-870, 746pro, and many other DSP rigs all make the same
stupid design flaw. Dual conversion DSP! No multiple pole xtal filter. No computer algorythm can emulate a multipe pole IF filter. These are your $2000-$3000 rigs The TS-850 had dual xtal IFs. However there was much junk from all the CPU's and yes up conversion, then downconversion and demod after the 2nd IF filter adds to the noise floor. How the R-7A did it was interesting. A 4 pole Fixed Xtal filter followed the upconverter. It has a pass band of 12kcs. That's right a 12Khz wide IF. This gives this collectors radio its used price tag of $2000. The 2nd IF used those 8 pole can filters. I found the K-2 has crystal clear SSB with the 1.8khz filter position. The R-7A the SSB gets muffled at 1.8khz. I use 1.8 khz only on the K2. The TR-7 used a 2 pole filter after up conversion. If you look at the schematic of the TS-850, you see the dual IFs are in the back of the receiver. So after upconversion the passband is 50kc wide. That is a large window for synth junk to get in. HOWEVER IF YOU USE CW filters in both IFs, your CW reception will be as good as a K2 The K2 wisely put much non xtal filtering right after the antenna jack. The band pass filters are wide enough for the Ham bands and very little general coverage. You lose general coverage ability of an R-7A. However do you really need a short wave rcvr in a ham rig? So yes one can compare the K2 with up to $3000 dollar rigs. However on SSB TX the K2 comes up average. It is average because the SSB adapter is a simple design. The all important audio chain is mostly in 2 chips. However I always get good audio reports. A RF proc of the TS-850's design would make the K2 rock. There is a cheap way of doing this. There are a few speech procs that go between the mic and rig. They are true RF procs. Your audio is up converted to 500kc. The 500Kc RF is processed by using an AGC like amp. At the RFstage more compression can be used with out AUDIO DISTORTION. Any RF clipping by products are filtered out. The DSB signal is then down converted back to audio with the exact same phase it entered the device. So one is feeding in audio that was RF processed. One can use up to 12db of RF processing. Audio processing gets distorted after 6db. One company makes this device for $60. It can be put in the mic or in the rig. I am ordering one. I will give on air checks for those that want too. _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
|
|
I remember I had one of the first of those external rf clipper
processors about 20 years ago... it was called Com-something. They used an "if" of about 50 kHz, with LC filters... it worked amazingly well and was sought after by DXers and contesters. Larry N8LP [hidden email] wrote: >You look at the TS-870, 746pro, and many other DSP rigs all make the same >stupid design flaw. > > Dual conversion DSP! No multiple pole xtal filter. >No computer algorythm can emulate a multipe pole IF filter. These are your >$2000-$3000 rigs > > The TS-850 had dual xtal IFs. However there was much junk from all the >CPU's and yes up conversion, then downconversion and demod after the 2nd IF >filter adds to the noise floor. > > How the R-7A did it was interesting. A 4 pole Fixed Xtal filter followed >the upconverter. >It has a pass band of 12kcs. That's right a 12Khz wide IF. This gives this >collectors radio >its used price tag of $2000. The 2nd IF used those 8 pole can filters. > > I found the K-2 has crystal clear SSB with the 1.8khz filter position. The >R-7A the SSB gets muffled at 1.8khz. I use 1.8 khz only on the K2. The TR-7 >used a 2 pole filter after up conversion. > > If you look at the schematic of the TS-850, you see the dual IFs are in >the back of the receiver. So after upconversion the passband is 50kc wide. That >is a large window for synth junk to get in. HOWEVER IF YOU USE CW filters in >both IFs, your CW reception will be as good as a K2 > > The K2 wisely put much non xtal filtering right after the antenna jack. >The band pass filters are wide enough for the Ham bands and very little general >coverage. You lose general coverage ability of an R-7A. However do you >really need a short wave rcvr in a ham rig? > > So yes one can compare the K2 with up to $3000 dollar rigs. >However on SSB TX the K2 comes up average. It is average because the SSB >adapter is a simple design. The all important audio chain is mostly in 2 chips. >However I always get good audio reports. A RF proc of the TS-850's design >would make the K2 rock. > > There is a cheap way of doing this. There are a few speech procs that go >between the mic and rig. They are true RF procs. Your audio is up converted to >500kc. The 500Kc RF is processed by using an AGC like amp. At the RFstage >more compression can be used with out AUDIO DISTORTION. Any RF clipping by >products are filtered out. The DSB signal is then down converted back to audio >with the exact same phase it entered the device. > > So one is feeding in audio that was RF processed. One can use up to 12db >of RF processing. Audio processing gets distorted after 6db. One company makes >this device for $60. It can be put in the mic or in the rig. > I am ordering one. I will give on air checks for those that want too. >_______________________________________________ >Elecraft mailing list >Post to: [hidden email] >You must be a subscriber to post to the list. >Subscriber Info (Addr. Change, sub, unsub etc.): > http://mailman.qth.net/mailman/listinfo/elecraft > >Help: http://mailman.qth.net/subscribers.htm >Elecraft web page: http://www.elecraft.com > > > > Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
Re: XTAL AND DSP simply is the best design
|
|
A British company called Datong brought out an RF clipper a few years back. It
used active filters to tailor the mic audio then CMOS switches to produce a DSB signal at 50kHz, diode clip it, and demod it back to audio. They made 3 products - an upmarket one with switches to select the clip level, one with pots on the front panel, and a board to fit in any suitable box or TX. It worked like a champ. They are still available on the second user market. I believe that a company in Germany now does an updated version. RF speech clipping is the most effective simple audio processing as it does not produce in-filter distortion products, unlike clipping at audio base band. 73 Stewart G3RXQ On Fri, 04 Mar 2005 03:33:31 -0500, Larry Phipps wrote: > I remember I had one of the first of those external rf clipper > > processors about 20 years ago... it was called Com-something. They used > an "if" of about 50 kHz, with LC filters... it worked amazingly well and > was sought after by DXers and contesters. > > Larry N8LP > > > [hidden email] wrote: > >> You look at the TS-870, 746pro, and many other DSP rigs all make the same >> stupid design flaw. >> >> Dual conversion DSP! No multiple pole xtal filter. >> No computer algorythm can emulate a multipe pole IF filter. These are your >> $2000-$3000 rigs >> >> The TS-850 had dual xtal IFs. However there was much junk from all the >> CPU's and yes up conversion, then downconversion and demod after the 2nd IF >> filter adds to the noise floor. >> >> How the R-7A did it was interesting. A 4 pole Fixed Xtal filter followed >> the upconverter. >> It has a pass band of 12kcs. That's right a 12Khz wide IF. This gives this >> collectors radio >> its used price tag of $2000. The 2nd IF used those 8 pole can filters. >> >> I found the K-2 has crystal clear SSB with the 1.8khz filter position. The >> R-7A the SSB gets muffled at 1.8khz. I use 1.8 khz only on the K2. The TR-7 >> used a 2 pole filter after up conversion. >> >> If you look at the schematic of the TS-850, you see the dual IFs are in >> the back of the receiver. So after upconversion the passband is 50kc wide. >> That >> is a large window for synth junk to get in. HOWEVER IF YOU USE CW filters >> in >> both IFs, your CW reception will be as good as a K2 >> >> The K2 wisely put much non xtal filtering right after the antenna jack. >> The band pass filters are wide enough for the Ham bands and very little >> general >> coverage. You lose general coverage ability of an R-7A. However do you >> really need a short wave rcvr in a ham rig? >> >> So yes one can compare the K2 with up to $3000 dollar rigs. >> However on SSB TX the K2 comes up average. It is average because the SSB >> adapter is a simple design. The all important audio chain is mostly in 2 >> chips. >> However I always get good audio reports. A RF proc of the TS-850's design >> would make the K2 rock. >> >> There is a cheap way of doing this. There are a few speech procs that go >> between the mic and rig. They are true RF procs. Your audio is up >> converted to >> 500kc. The 500Kc RF is processed by using an AGC like amp. At the RFstage >> more compression can be used with out AUDIO DISTORTION. Any RF clipping by >> products are filtered out. The DSB signal is then down converted back to >> audio >> with the exact same phase it entered the device. >> >> So one is feeding in audio that was RF processed. One can use up to 12db >> of RF processing. Audio processing gets distorted after 6db. One company >> makes >> this device for $60. It can be put in the mic or in the rig. >> I am ordering one. I will give on air checks for those that want too. >> _______________________________________________ >> Elecraft mailing list >> Post to: [hidden email] >> You must be a subscriber to post to the list. >> Subscriber Info (Addr. Change, sub, unsub etc.): >> http://mailman.qth.net/mailman/listinfo/elecraft >> >> Help: http://mailman.qth.net/subscribers.htm >> Elecraft web page: http://www.elecraft.com >> >> > _______________________________________________ > Elecraft mailing list > Post to: [hidden email] > You must be a subscriber to post to the list. > Subscriber Info (Addr. Change, sub, unsub etc.): > http://mailman.qth.net/mailman/listinfo/elecraft > > Help: http://mailman.qth.net/subscribers.htm > Elecraft web page: http://www.elecraft.com _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
R: XTAL AND DSP simply is the best design
|
|
Yes I can confirm it! I got it abt 15 yaers ago and used and had a great
succes in QRP/SSB. I still have it, but now I use just CW and don't use the clipper now. Look for this type and you'll have very good results. Best 72 Alex I0SKK -----Messaggio originale----- Da: [hidden email] [mailto:[hidden email]]Per conto di Stewart Baker Inviato: venerdì 4 marzo 2005 10.10 A: [hidden email]; [hidden email] Cc: [hidden email] Oggetto: Re: [Elecraft] XTAL AND DSP simply is the best design A British company called Datong brought out an RF clipper a few years back. It used active filters to tailor the mic audio then CMOS switches to produce a DSB signal at 50kHz, diode clip it, and demod it back to audio. They made 3 products - an upmarket one with switches to select the clip level, one with pots on the front panel, and a board to fit in any suitable box or TX. It worked like a champ. They are still available on the second user market. I believe that a company in Germany now does an updated version. RF speech clipping is the most effective simple audio processing as it does not produce in-filter distortion products, unlike clipping at audio base band. 73 Stewart G3RXQ On Fri, 04 Mar 2005 03:33:31 -0500, Larry Phipps wrote: > I remember I had one of the first of those external rf clipper > > processors about 20 years ago... it was called Com-something. They used > an "if" of about 50 kHz, with LC filters... it worked amazingly well and > was sought after by DXers and contesters. > > Larry N8LP > > > [hidden email] wrote: > >> You look at the TS-870, 746pro, and many other DSP rigs all make the same >> stupid design flaw. >> >> Dual conversion DSP! No multiple pole xtal filter. >> No computer algorythm can emulate a multipe pole IF filter. These are >> $2000-$3000 rigs >> >> The TS-850 had dual xtal IFs. However there was much junk from all the >> CPU's and yes up conversion, then downconversion and demod after the 2nd IF >> filter adds to the noise floor. >> >> How the R-7A did it was interesting. A 4 pole Fixed Xtal filter followed >> the upconverter. >> It has a pass band of 12kcs. That's right a 12Khz wide IF. This gives this >> collectors radio >> its used price tag of $2000. The 2nd IF used those 8 pole can filters. >> >> I found the K-2 has crystal clear SSB with the 1.8khz filter position. The >> R-7A the SSB gets muffled at 1.8khz. I use 1.8 khz only on the K2. The TR-7 >> used a 2 pole filter after up conversion. >> >> If you look at the schematic of the TS-850, you see the dual IFs are in >> the back of the receiver. So after upconversion the passband is 50kc wide. >> That >> is a large window for synth junk to get in. HOWEVER IF YOU USE CW filters >> in >> both IFs, your CW reception will be as good as a K2 >> >> The K2 wisely put much non xtal filtering right after the antenna jack. >> The band pass filters are wide enough for the Ham bands and very little >> general >> coverage. You lose general coverage ability of an R-7A. However do you >> really need a short wave rcvr in a ham rig? >> >> So yes one can compare the K2 with up to $3000 dollar rigs. >> However on SSB TX the K2 comes up average. It is average because the SSB >> adapter is a simple design. The all important audio chain is mostly in 2 >> chips. >> However I always get good audio reports. A RF proc of the TS-850's design >> would make the K2 rock. >> >> There is a cheap way of doing this. There are a few speech procs that go >> between the mic and rig. They are true RF procs. Your audio is up >> converted to >> 500kc. The 500Kc RF is processed by using an AGC like amp. At the >> more compression can be used with out AUDIO DISTORTION. Any RF clipping by >> products are filtered out. The DSB signal is then down converted back to >> audio >> with the exact same phase it entered the device. >> >> So one is feeding in audio that was RF processed. One can use up to 12db >> of RF processing. Audio processing gets distorted after 6db. One company >> makes >> this device for $60. It can be put in the mic or in the rig. >> I am ordering one. I will give on air checks for those that want too. >> _______________________________________________ >> Elecraft mailing list >> Post to: [hidden email] >> You must be a subscriber to post to the list. >> Subscriber Info (Addr. Change, sub, unsub etc.): >> http://mailman.qth.net/mailman/listinfo/elecraft >> >> Help: http://mailman.qth.net/subscribers.htm >> Elecraft web page: http://www.elecraft.com >> >> > _______________________________________________ > Elecraft mailing list > Post to: [hidden email] > You must be a subscriber to post to the list. > Subscriber Info (Addr. Change, sub, unsub etc.): > http://mailman.qth.net/mailman/listinfo/elecraft > > Help: http://mailman.qth.net/subscribers.htm > Elecraft web page: http://www.elecraft.com _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com -- No virus found in this incoming message. Checked by AVG Anti-Virus. Version: 7.0.300 / Virus Database: 266.6.0 - Release Date: 02/03/05 -- No virus found in this outgoing message. Checked by AVG Anti-Virus. Version: 7.0.300 / Virus Database: 266.6.0 - Release Date: 02/03/05 _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
Re: XTAL AND DSP simply is the best design
|
|
In reply to this post by WA2JJH
On Mar 4, 2005, at 2:07 AM, [hidden email] wrote: > You look at the TS-870, 746pro, and many other DSP rigs all make the > same > stupid design flaw. > > Dual conversion DSP! No multiple pole xtal filter. > No computer algorythm can emulate a multipe pole IF filter. That's not true. In theory, it is possible for DSP filters to produce filters with far, far better characteristics than multiple-pole crystal or mechanical filters. The real problem is reducing it to practice. You'd need DSP functioning at RF frequencies -- not AF as many rigs today. But, as the sample rate goes up, so does the required processing power. An audio-level DSP is a compromise. > The TS-850 had dual xtal IFs. However there was much junk from all > the > CPU's and yes up conversion, then downconversion and demod after the > 2nd IF > filter adds to the noise floor. The 850 is still a great radio. > How the R-7A did it was interesting. A 4 pole Fixed Xtal filter > followed > the upconverter. > It has a pass band of 12kcs. That's right a 12Khz wide IF. > The 2nd IF used those 8 pole can filters. This is typical for modern transceivers with general-coverage receive. Most of them have a first filter of 15 kHz, typically to support NBFM. They usually have good dynamic range over 20 kHz splits, but this degrades markedly at 5 kHz. That's why the Orion and the IC-7800 have multiple roofing filters. > The K2 wisely put much non xtal filtering right after the antenna > jack. > The band pass filters are wide enough for the Ham bands and very > little general > coverage. You lose general coverage ability of an R-7A. However do you > really need a short wave rcvr in a ham rig? It's certainly a specific design decision. Most solid-state japanese-made rigs from the mid-80s touted general-coverage receive as a feature. Other manufacturers have seen this benefit as well. Ten-Tec had a micro-processor controlled rig with general coverage receive. It had some problems in the receiver chain because of all the junk put out by the heterodyne PLL. Suddenly, it occurred to someone to go back to a crystal-controlled heterodyne oscillator. This meant losing general-coverage receive and using a bunch of crystals. But, for a brief time, the Omni-V was one of the best receivers on the market. The K2 is a much more clever design -- still no general-coverage receive, but it covers all 10 MF/HF ham bands quite well. Bill Coleman, AA4LR, PP-ASEL Mail: [hidden email] Quote: "Not within a thousand years will man ever fly!" -- Wilbur Wright, 1901 _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
«
Return to Elecraft
|
1 view|%1 views
| Free forum by Nabble | Edit this page |