RE: [AMRadio] FW: Homebrew receiver
Larry, I did use the 6BE6 as the mixer, works great! The IF amps are 6BA6 tubes, the detector is a 6BJ8(triode, twin diode), the S meter amp is a 12AU7, the LO is a 6C4, and the bfo (455Khz xtal osc) is a 6BH6. I had problems with the 6BZ6 tubes I tried to use as IF amps and changed to the 6BA6 tubes, but likely could have got the 6BZ6 tubes to work if I wanted to play around with things for a while. Even though the 6BE6 is supposed to be a noisy mixer, using two separate grids for antenna input and LO input, the receiver is VERY quiet. Its a bit hard to get used to, when things are quiet, they are REALLY quiet, and I think something is wrong, or the antenna fell down. There is no problem using these tubes on the lower frequencies, not sure about higher frequencies... Brett N2DTS Brett, The miniature equivalent of the 12SA7 is the 12BE6. Some characteristics may differ slightly, but I think it's as close as you'll find. -Larry Brett Gazdzinski wrote: If its not quiet, maybe I will try to duplicate the design of the first receiver using a 7 or 9 pin tube in place of the 12SA7. I am sure there is a tube to replace the 12SA7 in a miniature type. ___ AMRadio mailing list AMRadio@mailman.qth.net http://mailman.qth.net/mailman/listinfo/amradio
Re: [AMRadio] FW: Homebrew receiver
Brett, The miniature equivalent of the 12SA7 is the 12BE6. Some characteristics may differ slightly, but I think it's as close as you'll find. -Larry Brett Gazdzinski wrote: If its not quiet, maybe I will try to duplicate the design of the first receiver using a 7 or 9 pin tube in place of the 12SA7. I am sure there is a tube to replace the 12SA7 in a miniature type.
RE: [AMRadio] FW: Homebrew receiver
I finished the power supplies, and tried all the mixer designs in the 1967 handbook, (page 99), circuit b was first, the load on the LO stage was too low and stopped oscillation. Circuit a, injecting he LO into the grid worked well, but tuning the antenna input circuit changed the frequency a lot! Both these designs need a buffer amp between the LO and the mixer to work. I built design c, like in the first homebrew, and it worked fine. I then hooked up the Kiwa filter board, and into the 1st IF amp, that went well, built the 2nd IF amp, and it works but has a nice oscillation, really strong! The antenna tuning circuit was built, and needed some fine tuning, and still needs more fine tuning, and the LO needs some adjustment, the frequency changed quite a bit after it was hooked up to the mixer. its a bit on the low side, and only tunes up to 3900 or there abouts. I tried some things with the IF oscillation, but got no place, the gain may have to be reduced, and things rewired a little, it looks ok, with very short leads between all the components, correct bypass caps, thick ground wires running to the center of the tube socket (metal post), so I don't know why it makes such a GOOD oscillator. I should look at the Gonset G76 I have, it uses two IF amps, but uses 12BA6 (6BA6) tubes, maybe I could duplicate its design and construction. I had problems with the 1st homebrew if amp oscillating, but forget how I corrected it... I still have the detector, S meter, muting, agc, and manual gain circuits to build. So far, it LOOKS very good, the chassis paint came out very nice, no extra holes, parts laid out straight and so on. Brett N2DTS
RE: [AMRadio] FW: Homebrew receiver
On all my AM rigs, I had to go with dc on the mike preamp, otherwise, I had a lot of hum on the high impedance input circuit, likely its better with a 600 ohm setup. Its easy to do tho, a diode and a cap, the size of the cap sets the dc voltage. The dc does not need to be pure at all, a little filtering reduces the hum to where you cant hear it. If its a problem with the 7360, you could do the same, and add a 6.3 volt zener diode... Brett N2DTS -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of Donald Chester Sent: Saturday, November 08, 2003 3:26 PM To: amradio@mailman.qth.net Subject: Re: [AMRadio] FW: Homebrew receiver There are several beam defection tubes in circulation during the 60's time frame. Unfortunately, none of them are directly interchangeable with each other unless one is willing to rewire several pins on the tube socket. Spec wise they are very close to each other. If anyone has the data, maybe you could post a list of all the beam deflection tubes of that era. I think they were widely used in tube-type color TV's. Sometimes the TV ones are cheaper than the 7360, but on the other hand, the cheap sweep tubes of the 60's now cost several times more than 6146B's. One problem I had with the 7360 was that the a.c. filament current would introduce hum into the circuit. The magnetic field from the filament would modulate the beam deflection enough to modulate it slightly at 60~. I am sure this was never a problem with the slopbucket rigs of that era since everything below about 500~ was rolled off anyway to produce communication quality, but it was certainnly noticeable in my homebrew SSB generator. Of course there is a very simple fix: use reasonalbly well filtered DC on the filament. I have found that to be necessary even with the 12AX7 1st amplifier stage of my mic preamp. _ Crave some Miles Davis or Grateful Dead? Your old favorites are always playing on MSN Radio Plus. Trial month free! http://join.msn.com/?page=offers/premiumradio ___ AMRadio mailing list AMRadio@mailman.qth.net http://mailman.qth.net/mailman/listinfo/amradio
Re: [AMRadio] FW: Homebrew receiver
Have the SS-1R, along with the SS-1V panadaptor, the matching speaker, and SS-1S noise silencer(actually have 4 noise silencers) for about the last 10 years. Great receiver and the panadaptor works well with it. Only the Clegg Intercepter uses the 7360 as a balanced mixer. The SS-1R uses 2 7360's as 1st and 2nd mixers. There is no RF Amplifier stage. National's NCX-3 and NCX-5 used a 7360 in the balanced modulator. The second iteration of the NCX-5, the MK II cast aside the 7360 in favor of the more conventional solid-state diodes in the balanced modulator. You're correct that power supply requirements, lead dress, and tube and component aging moved them away from the 7360. Swan and Gonset also used this tube. There are several beam defection tubes in circulation during the 60's time frame. Unfortunately, none of them are directly interchangeable with each other unless one is willing to rewire several pins on the tube socket. Spec wise they are very close to each other. Pete, wa2cwa On Thu, 6 Nov 2003 13:46:10 -0500 [EMAIL PROTECTED] writes: Hi Pete, Congratulations on the SS-1R! Do you have the panadaptor for it too? A friend has them both and they're quite an interesting set up. I have an Interceptor and Interceptor II and I seem to remember that one of them uses the 7360 as a mixer. However, I think it mixes the output of a crystal oscillator with the VFO -- like Drake does in the 4 line -- rather than using the tube as the first conversion mixer. Of course the Interceptor is basically a 6m receiver with built-in 2m meter convertor, but I'm referring to the convertor in the main or 6m receiver. I have an RCA receiving tube manual from 1971 that describes the application of the 7360 as a balanced modulator or mixer. I think the tube can work very well, but requires attention to power supply purity and lead dress to maintain balance in the circuit. 73, Ed N3CMI The best thing to hit the internet in years - Juno SpeedBand! Surf the web up to FIVE TIMES FASTER! Only $14.95/ month - visit www.juno.com to sign up today!
Re: [AMRadio] FW: Homebrew receiver
Hi Pete, Your e-mail, aside from provoking my BA-envy response ;-) - reminded me that I need to order the big Signal One CX-7 operating and service manual. It's listed in your catalog for $49.20, must be a big mutha! Can you take payment via Paypal? Much faster, if so I'll do it today, just let me know what your account name is. Thanks and 73, Bob W9RAN
Re: [AMRadio] FW: Homebrew receiver
Ed: Have the SS-1R, along with the SS-1V panadaptor, the matching speaker, and SS-1S noise silencer(actually have 4 noise silencers) for about the last 10 years. Great receiver and the panadaptor works well with it. Only the Clegg Intercepter uses the 7360 as a balanced mixer. The SS-1R uses 2 7360's as 1st and 2nd mixers. There is no RF Amplifier stage. National's NCX-3 and NCX-5 used a 7360 in the balanced modulator. The second iteration of the NCX-5, the MK II cast aside the 7360 in favor of the more conventional solid-state diodes in the balanced modulator. You're correct that power supply requirements, lead dress, and tube and component aging moved them away from the 7360. Swan and Gonset also used this tube. There are several beam defection tubes in circulation during the 60's time frame. Unfortunately, none of them are directly interchangeable with each other unless one is willing to rewire several pins on the tube socket. Spec wise they are very close to each other. Pete, wa2cwa On Thu, 6 Nov 2003 13:46:10 -0500 [EMAIL PROTECTED] writes: Hi Pete, Congratulations on the SS-1R! Do you have the panadaptor for it too? A friend has them both and they're quite an interesting set up. I have an Interceptor and Interceptor II and I seem to remember that one of them uses the 7360 as a mixer. However, I think it mixes the output of a crystal oscillator with the VFO -- like Drake does in the 4 line -- rather than using the tube as the first conversion mixer. Of course the Interceptor is basically a 6m receiver with built-in 2m meter convertor, but I'm referring to the convertor in the main or 6m receiver. I have an RCA receiving tube manual from 1971 that describes the application of the 7360 as a balanced modulator or mixer. I think the tube can work very well, but requires attention to power supply purity and lead dress to maintain balance in the circuit. 73, Ed N3CMI The best thing to hit the internet in years - Juno SpeedBand! Surf the web up to FIVE TIMES FASTER! Only $14.95/ month - visit www.juno.com to sign up today!
Re: [AMRadio] FW: Homebrew receiver
Hey Ed: Have the SS-1R, along with the SS-1V panadaptor, the matching speaker, and SS-1S noise silencer(actually have 4 noise silencers) for about the last 10 years. Great receiver and the panadaptor works well with it. Only the Clegg Intercepter uses the 7360 as a balanced mixer. The SS-1R uses 2 7360's as 1st and 2nd mixers. There is no RF Amplifier stage. National's NCX-3 and NCX-5 used a 7360 in the balanced modulator. The second iteration of the NCX-5, the MK II cast aside the 7360 in favor of the more conventional solid-state diodes in the balanced modulator. You're correct that power supply requirements, lead dress, and tube and component aging moved them away from the 7360. Swan and Gonset also used this tube. There are several beam defection tubes in circulation during the 60's time frame. Unfortunately, none of them are directly interchangeable with each other unless one is willing to rewire several pins on the tube socket. Spec wise they are very close to each other. Pete, wa2cwa On Thu, 6 Nov 2003 13:46:10 -0500 [EMAIL PROTECTED] writes: Hi Pete, Congratulations on the SS-1R! Do you have the panadaptor for it too? A friend has them both and they're quite an interesting set up. I have an Interceptor and Interceptor II and I seem to remember that one of them uses the 7360 as a mixer. However, I think it mixes the output of a crystal oscillator with the VFO -- like Drake does in the 4 line -- rather than using the tube as the first conversion mixer. Of course the Interceptor is basically a 6m receiver with built-in 2m meter convertor, but I'm referring to the convertor in the main or 6m receiver. I have an RCA receiving tube manual from 1971 that describes the application of the 7360 as a balanced modulator or mixer. I think the tube can work very well, but requires attention to power supply purity and lead dress to maintain balance in the circuit. 73, Ed N3CMI Clegg Intercepter receiver for 6 and 2 meters also used the 7360 as a mixer. In my Squires Sanders SS-1R receiver, with no signals present and the antenna connected, the receiver is very quiet. It comes to life when you tune a signal. The receiver was not very tolerant of random length antennas or antennas that didn't provide a decent match to the frequencies you wanted to receive. The 7360 was also used as a balanced modulator in a number of 60's sweep tube SSB transceivers. Pete, wa2cwa On Thu, 06 Nov 2003 09:42:23 -0500 Brett Gazdzinski [EMAIL PROTECTED] writes: Well, I never even seen a Squires Sanders receiver, let alone listened to one! I cant recall offhand any other receiver that used a 7360 as a mixer, but need to look in my vacuum tube receiver book, it lists all the receivers with their tube lineups. The ARRL sure liked the 7360, they used it in a lot of their receiver projects, in the 1967 handbook anyway. I suspect the cost of a 7360 was lower back then, not sure why its so expensive now, must be very rare? On the lower bands, I am not sure getting a really quiet mixer is important at all, but have not tried the other designs yet. I never realized just how noisy some receivers are till the first homebrew was done and compared it to the R390A. I guess you think its atmospheric noise, or just get used to it, but I cant stand the R390a anymore. The first homebrew receiver is VERY quiet, but is an odd design, I hope the new one is fairly quiet with the design I picked. If its not quiet, maybe I will try to duplicate the design of the first receiver using a 7 or 9 pin tube in place of the 12SA7. I am sure there is a tube to replace the 12SA7 in a miniature type. Maybe I should have planned it that way from the start, go with what you know works well, but trying other things is part of the fun... It will be easy to change the tube type if the first design does not work out (6AH6, cathode injected LO). Brett N2DTS The Squires Sanders SS-1R and SS-IBS both used a pair of 7360s. I never had a 1R, but I never thought the IBS worked noticeably better than any other relatively high end radio with more conventional vacuum tube mixer circuitry like the NC400 or the 51J4. And the thing was harder to align correctly as well (maybe that's why I won't impressed = never got it right:) Scott The best thing to hit the internet in years - Juno SpeedBand! Surf the web up to FIVE TIMES FASTER! Only $14.95/ month - visit www.juno.com to sign up today!
Re: [AMRadio] FW: Homebrew receiver
There are several beam defection tubes in circulation during the 60's time frame. Unfortunately, none of them are directly interchangeable with each other unless one is willing to rewire several pins on the tube socket. Spec wise they are very close to each other. If anyone has the data, maybe you could post a list of all the beam deflection tubes of that era. I think they were widely used in tube-type color TV's. Sometimes the TV ones are cheaper than the 7360, but on the other hand, the cheap sweep tubes of the 60's now cost several times more than 6146B's. One problem I had with the 7360 was that the a.c. filament current would introduce hum into the circuit. The magnetic field from the filament would modulate the beam deflection enough to modulate it slightly at 60~. I am sure this was never a problem with the slopbucket rigs of that era since everything below about 500~ was rolled off anyway to produce communication quality, but it was certainnly noticeable in my homebrew SSB generator. Of course there is a very simple fix: use reasonalbly well filtered DC on the filament. I have found that to be necessary even with the 12AX7 1st amplifier stage of my mic preamp. _ Crave some Miles Davis or Grateful Dead? Your old favorites are always playing on MSN Radio Plus. Trial month free! http://join.msn.com/?page=offers/premiumradio
RE: [AMRadio] FW: Homebrew receiver
Two tuned circuits using B+W coil stock, seems to have a very high Q, directly into the mixer, out to the Kiwa filter (no loss), into the IF amps. What kind of filter is the Kiwa (crystal, mechanical, ceramic?), and do you say they have no insertion loss? What is the skirt selectivity like? What bandwidths are available, and where can one purchase them? Don _ MSN Messenger with backgrounds, emoticons and more. http://www.msnmessenger-download.com/tracking/cdp_customize
Re: [AMRadio] FW: Homebrew receiver
Hello: You can checkout Kiwa at their website: http://www.kiwa.com 73, Bruce WA8TNC = Donald Chester wrote: What kind of filter is the Kiwa (crystal, mechanical, ceramic?), and do you say they have no insertion loss? What is the skirt selectivity like? What bandwidths are available, and where can one purchase them? Don
Re: [AMRadio] FW: Homebrew receiver
Don... Go to www.kiwa.com check out the manufacturer's website... Contains some FB info, will doubtlessly answer all of your questions. ~73!~ Eddy VE3CUI - VE3XZ - Original Message - From: Donald Chester [EMAIL PROTECTED] To: amradio@mailman.qth.net Sent: Friday, November 07, 2003 2:39 AM Subject: RE: [AMRadio] FW: Homebrew receiver Two tuned circuits using B+W coil stock, seems to have a very high Q, directly into the mixer, out to the Kiwa filter (no loss), into the IF amps. What kind of filter is the Kiwa (crystal, mechanical, ceramic?), and do you say they have no insertion loss? What is the skirt selectivity like? What bandwidths are available, and where can one purchase them? Don _ MSN Messenger with backgrounds, emoticons and more. http://www.msnmessenger-download.com/tracking/cdp_customize ___ AMRadio mailing list AMRadio@mailman.qth.net http://mailman.qth.net/mailman/listinfo/amradio
RE: [AMRadio] FW: Homebrew receiver
Don, I think the kiwa filters are the best thing since sliced bread! They use an op amp input, into three ceramic filters, picked to give the bandwidth you want, and an op amp output. It runs off 8 to 30 volts, and is about the size of a postage stamp. They come with shielded wires to hook up to the IF and power. The shape factor seems quite similar to a good mechanical filter, very steep sides. In use, if someone is not wide (splatter), you can tune just off them and cant tell they are there at all. 5kc separation works fine with these filters. I have a 5.5Kc filter in the first homebrew, and got a filter board with switching diodes and two filters on it for the new homebrew. I picked 4.5 and 5.5Kc, 5.5 seems good fidelity, and works very well under most conditions, the 4.5 will be for when things get rough. Comparing the filter to the R390A filters, 4Kc is to narrow, 8 is to wide, but the 5.5 Kiwa filter is just right for me. People with ears that hear over 4kc might want wider filters. You can buy them in .5Kc increments, and they can come with 450 volt input and output caps for tube circuits. You just tack the filter on in the IF, after the mixer and before the first IF transformer. They cost $50.00, a web search on Kiwa will get their web site. They also make LCR meters, preamps, BC filters, and other stuff. A lot of their stuff is to improve various modern receivers. The filters may work so well, because they operate into just what they want to see, not loaded by the circuit, and they are very small and likely shielded well. I think 90% of the reason my receiver works so well is because of these filters. The filters will work in ANYTHING that uses a 455Khz IF frequency. Seems to work great, two high Q tuned circuits before the mixer, very good filter on the mixer output, really limits stuff you don't want from the receiver. I think these filters could really transform any older receivers that use a 455Khz IF frequency, and should try some in the Scott and the SX17, or even the R390A, get rid of 16Kc filter and put in a 5.5 or 6Kc Kiwa. You would then have 4, 5.5 (or 6), and 8 Kc, just the ticket for AM. In the 75S1, in place of the back to back IF cans, a Kiwa would be great, an add on low distortion AM detector, and you have a GREAT receiver in a small package. Even for something like a 75A4, the $50.00 Kiwa filters would cost much less then the mechanical filters, and they come in any bandwidth you want. I think you could solder the wires from the Kiwa filter onto pins you could plug into a mechanical filter socket... Plug and play! http://www.kiwa.com/ Brett N2DTS What kind of filter is the Kiwa (crystal, mechanical, ceramic?), and do you say they have no insertion loss? What is the skirt selectivity like? What bandwidths are available, and where can one purchase them? Don
Re: [AMRadio] FW: Homebrew receiver
They show only nominal bandwidths for the LFH-4S and LFH-6S filters. Does anyone know what the 6 dB bandwidth and shape factor is for these filters? To my way of thinking, one would be better off with a passive filter and all amplification after the filter, than with active filtering, or several stages of filtering with some amplification between each. Don K4KYV _ Concerned that messages may bounce because your Hotmail account is over limit? Get Hotmail Extra Storage! http://join.msn.com/?PAGE=features/es
RE: [AMRadio] FW: Homebrew receiver
Don, On their web page, there are charts of the bandwidth, of the 3.5, 5.5 and 8 kc filters. They also list the shape factors. In operation, I don't doubt the filters exceed the published specs, they seem to in my receiver. I could not expect any better performance out of a filter. You have an op amp on the input, 3 filters of slightly different frequencies in parallel, like they sometimes do with crystals, and an op amp output. As I tune through a carrier slowly, I can see each filter peak. I called them and spoke to the owner, I think its all done at his house or small shop, and he was very helpful and friendly. Brett N2DTS They show only nominal bandwidths for the LFH-4S and LFH-6S filters. Does anyone know what the 6 dB bandwidth and shape factor is for these filters? To my way of thinking, one would be better off with a passive filter and all amplification after the filter, than with active filtering, or several stages of filtering with some amplification between each. Don K4KYV _ Concerned that messages may bounce because your Hotmail account is over limit? Get Hotmail Extra Storage! http://join.msn.com/?PAGE=features/es ___ AMRadio mailing list AMRadio@mailman.qth.net http://mailman.qth.net/mailman/listinfo/amradio
RE: [AMRadio] FW: Homebrew receiver
Well, I never even seen a Squires Sanders receiver, let alone listened to one! I cant recall offhand any other receiver that used a 7360 as a mixer, but need to look in my vacuum tube receiver book, it lists all the receivers with their tube lineups. The ARRL sure liked the 7360, they used it in a lot of their receiver projects, in the 1967 handbook anyway. I suspect the cost of a 7360 was lower back then, not sure why its so expensive now, must be very rare? On the lower bands, I am not sure getting a really quiet mixer is important at all, but have not tried the other designs yet. I never realized just how noisy some receivers are till the first homebrew was done and compared it to the R390A. I guess you think its atmospheric noise, or just get used to it, but I cant stand the R390a anymore. The first homebrew receiver is VERY quiet, but is an odd design, I hope the new one is fairly quiet with the design I picked. If its not quiet, maybe I will try to duplicate the design of the first receiver using a 7 or 9 pin tube in place of the 12SA7. I am sure there is a tube to replace the 12SA7 in a miniature type. Maybe I should have planned it that way from the start, go with what you know works well, but trying other things is part of the fun... It will be easy to change the tube type if the first design does not work out (6AH6, cathode injected LO). Brett N2DTS The Squires Sanders SS-1R and SS-IBS both used a pair of 7360s. I never had a 1R, but I never thought the IBS worked noticeably better than any other relatively high end radio with more conventional vacuum tube mixer circuitry like the NC400 or the 51J4. And the thing was harder to align correctly as well (maybe that's why I won't impressed = never got it right:) Scott
Re: [AMRadio] FW: Homebrew receiver
Clegg Intercepter receiver for 6 and 2 meters also used the 7360 as a mixer. In my Squires Sanders SS-1R receiver, with no signals present and the antenna connected, the receiver is very quiet. It comes to life when you tune a signal. The receiver was not very tolerant of random length antennas or antennas that didn't provide a decent match to the frequencies you wanted to receive. The 7360 was also used as a balanced modulator in a number of 60's sweep tube SSB transceivers. Pete, wa2cwa On Thu, 06 Nov 2003 09:42:23 -0500 Brett Gazdzinski [EMAIL PROTECTED] writes: Well, I never even seen a Squires Sanders receiver, let alone listened to one! I cant recall offhand any other receiver that used a 7360 as a mixer, but need to look in my vacuum tube receiver book, it lists all the receivers with their tube lineups. The ARRL sure liked the 7360, they used it in a lot of their receiver projects, in the 1967 handbook anyway. I suspect the cost of a 7360 was lower back then, not sure why its so expensive now, must be very rare? On the lower bands, I am not sure getting a really quiet mixer is important at all, but have not tried the other designs yet. I never realized just how noisy some receivers are till the first homebrew was done and compared it to the R390A. I guess you think its atmospheric noise, or just get used to it, but I cant stand the R390a anymore. The first homebrew receiver is VERY quiet, but is an odd design, I hope the new one is fairly quiet with the design I picked. If its not quiet, maybe I will try to duplicate the design of the first receiver using a 7 or 9 pin tube in place of the 12SA7. I am sure there is a tube to replace the 12SA7 in a miniature type. Maybe I should have planned it that way from the start, go with what you know works well, but trying other things is part of the fun... It will be easy to change the tube type if the first design does not work out (6AH6, cathode injected LO). Brett N2DTS The Squires Sanders SS-1R and SS-IBS both used a pair of 7360s. I never had a 1R, but I never thought the IBS worked noticeably better than any other relatively high end radio with more conventional vacuum tube mixer circuitry like the NC400 or the 51J4. And the thing was harder to align correctly as well (maybe that's why I won't impressed = never got it right:) Scott The best thing to hit the internet in years - Juno SpeedBand! Surf the web up to FIVE TIMES FASTER! Only $14.95/ month - visit www.juno.com to sign up today!
Re: [AMRadio] FW: Homebrew receiver
Hi Pete, Congratulations on the SS-1R! Do you have the panadaptor for it too? A friend has them both and they're quite an interesting set up. I have an Interceptor and Interceptor II and I seem to remember that one of them uses the 7360 as a mixer. However, I think it mixes the output of a crystal oscillator with the VFO -- like Drake does in the 4 line -- rather than using the tube as the first conversion mixer. Of course the Interceptor is basically a 6m receiver with built-in 2m meter convertor, but I'm referring to the convertor in the main or 6m receiver. I have an RCA receiving tube manual from 1971 that describes the application of the 7360 as a balanced modulator or mixer. I think the tube can work very well, but requires attention to power supply purity and lead dress to maintain balance in the circuit. 73, Ed N3CMI [EMAIL PROTECTED] m Sent by: To [EMAIL PROTECTED] amradio@mailman.qth.net lman.qth.net cc Subject 11/06/2003 01:37 Re: [AMRadio] FW: Homebrew receiver PM Please respond to [EMAIL PROTECTED] th.net Clegg Intercepter receiver for 6 and 2 meters also used the 7360 as a mixer. In my Squires Sanders SS-1R receiver, with no signals present and the antenna connected, the receiver is very quiet. It comes to life when you tune a signal. The receiver was not very tolerant of random length antennas or antennas that didn't provide a decent match to the frequencies you wanted to receive. The 7360 was also used as a balanced modulator in a number of 60's sweep tube SSB transceivers. Pete, wa2cwa On Thu, 06 Nov 2003 09:42:23 -0500 Brett Gazdzinski [EMAIL PROTECTED] writes: Well, I never even seen a Squires Sanders receiver, let alone listened to one! I cant recall offhand any other receiver that used a 7360 as a mixer, but need to look in my vacuum tube receiver book, it lists all the receivers with their tube lineups. The ARRL sure liked the 7360, they used it in a lot of their receiver projects, in the 1967 handbook anyway. I suspect the cost of a 7360 was lower back then, not sure why its so expensive now, must be very rare? On the lower bands, I am not sure getting a really quiet mixer is important at all, but have not tried the other designs yet. I never realized just how noisy some receivers are till the first homebrew was done and compared it to the R390A. I guess you think its atmospheric noise, or just get used to it, but I cant stand the R390a anymore. The first homebrew receiver is VERY quiet, but is an odd design, I hope the new one is fairly quiet with the design I picked. If its not quiet, maybe I will try to duplicate the design of the first receiver using a 7 or 9 pin tube in place of the 12SA7. I am sure there is a tube to replace the 12SA7 in a miniature type. Maybe I should have planned it that way from the start, go with what you know works well, but trying other things is part of the fun... It will be easy to change the tube type if the first design does not work out (6AH6, cathode injected LO). Brett N2DTS The Squires Sanders SS-1R and SS-IBS both used a pair of 7360s. I never had a 1R, but I never thought the IBS worked noticeably better than any other relatively high end radio with more conventional vacuum tube mixer circuitry like the NC400 or the 51J4. And the thing was harder to align correctly as well (maybe that's why I won't impressed = never got it right:) Scott The best thing to hit the internet in years - Juno SpeedBand! Surf the web up to FIVE TIMES FASTER! Only $14.95/ month - visit www.juno.com to sign up today! ___ AMRadio mailing list AMRadio@mailman.qth.net http://mailman.qth.net/mailman/listinfo/amradio
RE: [AMRadio] FW: Homebrew receiver
The Gonset G76 also uses the 7360. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of [EMAIL PROTECTED] Sent: Thursday, November 06, 2003 1:37 PM To: amradio@mailman.qth.net Subject: Re: [AMRadio] FW: Homebrew receiver Clegg Intercepter receiver for 6 and 2 meters also used the 7360 as a mixer. In my Squires Sanders SS-1R receiver, with no signals present and the antenna connected, the receiver is very quiet. It comes to life when you tune a signal. The receiver was not very tolerant of random length antennas or antennas that didn't provide a decent match to the frequencies you wanted to receive. The 7360 was also used as a balanced modulator in a number of 60's sweep tube SSB transceivers. Pete, wa2cwa On Thu, 06 Nov 2003 09:42:23 -0500 Brett Gazdzinski [EMAIL PROTECTED] writes: Well, I never even seen a Squires Sanders receiver, let alone listened to one! I cant recall offhand any other receiver that used a 7360 as a mixer, but need to look in my vacuum tube receiver book, it lists all the receivers with their tube lineups. The ARRL sure liked the 7360, they used it in a lot of their receiver projects, in the 1967 handbook anyway. I suspect the cost of a 7360 was lower back then, not sure why its so expensive now, must be very rare? On the lower bands, I am not sure getting a really quiet mixer is important at all, but have not tried the other designs yet. I never realized just how noisy some receivers are till the first homebrew was done and compared it to the R390A. I guess you think its atmospheric noise, or just get used to it, but I cant stand the R390a anymore. The first homebrew receiver is VERY quiet, but is an odd design, I hope the new one is fairly quiet with the design I picked. If its not quiet, maybe I will try to duplicate the design of the first receiver using a 7 or 9 pin tube in place of the 12SA7. I am sure there is a tube to replace the 12SA7 in a miniature type. Maybe I should have planned it that way from the start, go with what you know works well, but trying other things is part of the fun... It will be easy to change the tube type if the first design does not work out (6AH6, cathode injected LO). Brett N2DTS The Squires Sanders SS-1R and SS-IBS both used a pair of 7360s. I never had a 1R, but I never thought the IBS worked noticeably better than any other relatively high end radio with more conventional vacuum tube mixer circuitry like the NC400 or the 51J4. And the thing was harder to align correctly as well (maybe that's why I won't impressed = never got it right:) Scott The best thing to hit the internet in years - Juno SpeedBand! Surf the web up to FIVE TIMES FASTER! Only $14.95/ month - visit www.juno.com to sign up today! ___ AMRadio mailing list AMRadio@mailman.qth.net http://mailman.qth.net/mailman/listinfo/amradio DISCLAIMER: The information contained in this e-mail may be confidential and is intended solely for the use of the named addressee. Access, copying or re-use of the e-mail or any information contained therein by any other person is not authorized. If you are not the intended recipient please notify us immediately by returning the e-mail to the originator.(A)
RE: [AMRadio] FW: Homebrew receiver
I cant recall offhand any other receiver that used a 7360 as a mixer, but need to look in my vacuum tube receiver book, it lists all the receivers with their tube lineups. The ARRL sure liked the 7360, they used it in a lot of their receiver projects, in the 1967 handbook anyway. I suspect the cost of a 7360 was lower back then, not sure why its so expensive now, must be very rare? I still have a few that I bought new back in mid 70's for about $12 each. There are a couple of beam deflection tubes similar to the 7360, made for TV applications. I believe one is the 6AR8, and there is another one without the wierd filament connection, but I forget the type number. The 7360 was used as a mixer in the Tempo One (an early, very flaky, Yaesu tube type SSB transceiver). In later models they replaced the 7360 with some kind of solid state mixer. The tube is probably expensive because it is rare, while there is equipment still in use that requires it. I once built a SSB generator using one as a balanced mixer. I successfully got it working, generating a near-hifi SSB signal at 64 kc/s using a Collins multiplexing asymmetrical mechanical filter from Ma Bell as the sideband filter. I lost interest in the project before building converter stages to translate the low-frequency signal to the amateur frequencies. I never realized just how noisy some receivers are till the first homebrew was done and compared it to the R390A. I guess you think its atmospheric noise, or just get used to it, but I cant stand the R390a anymore. The problem with the R-390A is that there are so many mixer stages ahead of the selectivity. Every mixer contributes to noise. The ultimate design for a practical receiver would be single conversion with no rf stage ahead of the mixer. It would use a selective enough front-end tuning network between the antenna and mixer to reject images, and the mixer would be low noise enough to hear all the way down to the atmospreric noise floor. The mixer would have high enough output level to feed directly into the selectivity filter with no amplifier stage between the mixer and filter. Following the filter, the i-f amplifier would be low noise and high gain enough to boost the signal to the level needed at the detector without raising the noise floor above that of the signal that exits the filter. One requirement would be a selectivity filter with minimal insertion loss. One interesting receiver design from before WWII used a separate tuned circuit to null out the image frequency. It was written up in QST, I believe (or was it RADIO?). Hallicrafters came out with a model or two that used the design, but it was swiftly discontinued. I think the problem was that the image null had to be a separate control from the main tuning because of the difficulty of getting the image null to accurately track with the rest of the receiver. This might be a worthwhile topic to research and apply to a no-compromise homebrew receiver. I am sure there is a tube to replace the 12SA7 in a miniature type. Zillions of them were used in the miniature tube version of the classic 5-tube ac/dc bc receiver. Isn't it a 12BE6? (My computer is in the house and all my radio reference material is out in the shack). Every commercially built receiver, ham or military, is one big compromise, designed to best meet the needs of diverse users. Don K4KYV _ Is your computer infected with a virus? Find out with a FREE computer virus scan from McAfee. Take the FreeScan now! http://clinic.mcafee.com/clinic/ibuy/campaign.asp?cid=3963
RE: [AMRadio] FW: Homebrew receiver
The ARRL handbook went with those like crazy, in the 1960's. I don't think I have any 7360 tubes. I did not look hard for them in the junk box. I DID look in the antique electronic supply catalog, and they wanted about $50.00 each I think! I should look in the junk box, since I may have some of these tubes, I got a BUNCH of industrial tubes with numbers out of some old sat com military stuff, many 7 and 9 pin tubes, the very nice black tube shields, and even a bunch of those big triodes(6sa7?). I cant say just how quiet those tubes are, since I never used one. Anyone know of a receiver that actually uses a 7360 as a mixer??? In the first home brew receiver I built, I used a 6SA7, but unlike other designs, it used a tube with three grids, injecting the antenna signal into the control grid, the LO into the suppressor grid. Most designs I looked at had 4 grids when separate injection was used, and would be in the very noisy category. This circuit was based on the Scott SLRM receiver I have. Mixer noise seems very very low on the homebrew, lowest of any receiver I have ever tried. I am not sure how important the noise figure is on 80 and 40 meters, on higher bands, I know its important, but I don't go up there. On comparison to very weak signals on a very clear quiet band, the homebrew will copy someone who is VERY weak, but give clear copy, on the R390a, I might not even be able to tell there is a signal there! I have not compared the homebrew directly to the Scott or the SX17, but they have bandwidth problems, going quite wide at 60 db down. That will likely add noise. For homebrew #2, I went with a 6ah6 in circuit design b in the handbook (1961?), control grid gets the antenna signal, the LO is injected into the cathode, suppressor grid is grounded, screen grid has screen voltage on it. Its supposed to be quiet. I can also inject both signals into the control grid, I may try both designs to see which works best. The receiver is moving along well, all the metal is cut, drilled, punched, and I will paint the chassis on this receiver. The B+W coil stock arrived, the filters arrived, this receiver will have selectable bandwidth, 4.5Khz and 5.5Khz. The LO coil (B+W coil stock) is mounted in a small metal box along with the band switch (shorts out some of the coil) along with the 40 meter tune cap, to adjust the 40 meter frequency, so I can set it up like homebrew #1, switching between 160, 80 and 40 meters has the receiver go to 1880, 3880, and 7290 when I change bands. The coil has been tested in the LO circuit for calibration... I broke down and bought a dremel tool, easy to make square holes for things like relays, power cord plug in (with filter), digital frequency display, etc. I need to find a good aluminum primer for painting the chassis. Brett N2DTS -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of Donald Chester Sent: Sunday, November 02, 2003 11:02 AM To: amradio@mailman.qth.net Subject: RE: [AMRadio] FW: Homebrew receiver I am not sure how much the RF amp adds to the noise level. A well designed rf amp section can actually reduce noise levels. Noise mostly comes from mixers, and overall tube counts. All mixers add some noise, some designs are much better than others, and the more there are, the more noise you get. I used single conversion, with a quiet mixer setup, and used two tuned circuits of very high Q in the input, along with resonant dipole antennas for 80 and 40 meters, so I don't get any images or other problems, as signals out of band are attenuated very much before making it to the mixer. I think the best mixer designed ever developed used the 7360 or similar beam deflection tube. I'd like other opinions on the subject, if anyone thinks there is anything else that actually surpasses the performance of these tubes in mixer service? Don K4KYV _ See when your friends are online with MSN Messenger 6.0. Download it now FREE! http://msnmessenger-download.com ___ AMRadio mailing list AMRadio@mailman.qth.net http://mailman.qth.net/mailman/listinfo/amradio
RE: [AMRadio] FW: Homebrew receiver
Well, sure, if you do something about the bandwidth choices, and the audio. Instead of paying what they are going for now, I think its much better to get a 75s1 for around $200.00/$300.00 and installing a kiwa filter in place of the back to back IF cans, and doing something about the audio, an internal IC chip running 5 watts, or an external audio amp, or even a sub board with a pair of push pull output tubes like 6aq5,s or something. Its much cheaper, smaller, just as stable and accurate. It does not have the same looks as a 75A4, but those are going for about $1000.00, then you have to hack it up to install other filters and audio If you have a 455Khz IF, Kiwa makes a filter board with two filters, switched in circuit by diodes. A very small switch is all that is needed, or you can use your own switch/spare contacts on an existing switch. Other receivers can be great, if they have a 455Khz IF, the r388, all the 75a receivers, the 75s receivers, other old receivers that have a 455Khz IF can have two choices of mechanical filter like bandwidth at low cost. Almost all receivers really benefit from a hi fidelity audio amp with big speaker. If you have a lot of receivers, it makes a lot of sense to go with ONE good amp and ONE big speaker. Makes it easy to record off the air, takes up less space, sounds really good, and saves loads of space. My Scott has a built in speaker, small but good sounding, and I do have a separate speaker hooked up to the SX17 for that great push pull output sound, but cant say they sound better than the Marantz amp. Brett N2DTS -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of Donald Chester Sent: Sunday, November 02, 2003 11:15 AM To: amradio@mailman.qth.net Subject: RE: [AMRadio] FW: Homebrew receiver My favorite style was the Collins 75a series I use a 75A4, which is often bashed by the AM folks, but I find it to be about the best receiver I have ever tried. If I find a truly superior receiver to the A4, I'll retire mine and change over to that. The main deficiency of the A4 is the audio. I use an outboard AF amp (an old 50's vintage 10w hi-fi amplifier using a pair of 6V6's in pushpull). I changed the .01 mfd coupling caps in the low level audio stages of the receiver to 0.1. Actually, I just bridged the .1's across the originals, to minimise melted plastic insulation on the wiring in the receiver. I pulled out the original 6AQ5 to save unnecessary drain on the power supply and to reduce heat generation. I also clipped out a couple of 510 pf mica caps that were added in later models to attenuate the high frequency response. From the diode detector to the audio output, the frequncy response is now almost flat from 30~ to about 5000~. On one of my A4's I added an outboard box with additional mechanical filters. The stock 3 selectivities is not enough if you want cw, ssb plus optimum AM under a variety of band condx. Don K4KYV _ Want to check if your PC is virus-infected? Get a FREE computer virus scan online from McAfee. http://clinic.mcafee.com/clinic/ibuy/campaign.asp?cid=3963 ___ AMRadio mailing list AMRadio@mailman.qth.net http://mailman.qth.net/mailman/listinfo/amradio
Re: [AMRadio] FW: Homebrew receiver
The Squires Sanders SS-1R and SS-IBS both used a pair of 7360s. I never had a 1R, but I never thought the IBS worked noticeably better than any other relatively high end radio with more conventional vacuum tube mixer circuitry like the NC400 or the 51J4. And the thing was harder to align correctly as well (maybe that's why I wan't impressed = never got it right:) Scott --- StripMime Report -- processed MIME parts --- multipart/alternative text/plain (text body -- kept) text/html The reason this message is shown is because the post was in HTML or had an attachment. Attachments are not allowed. To learn how to post in Plain-Text go to: http://www.expita.com/nomime.html ---
RE: [AMRadio] FW: Homebrew receiver
I am not sure how much the RF amp adds to the noise level. A well designed rf amp section can actually reduce noise levels. Noise mostly comes from mixers, and overall tube counts. All mixers add some noise, some designs are much better than others, and the more there are, the more noise you get. I used single conversion, with a quiet mixer setup, and used two tuned circuits of very high Q in the input, along with resonant dipole antennas for 80 and 40 meters, so I don't get any images or other problems, as signals out of band are attenuated very much before making it to the mixer. I think the best mixer designed ever developed used the 7360 or similar beam deflection tube. I'd like other opinions on the subject, if anyone thinks there is anything else that actually surpasses the performance of these tubes in mixer service? Don K4KYV _ See when your friends are online with MSN Messenger 6.0. Download it now FREE! http://msnmessenger-download.com
RE: [AMRadio] FW: Homebrew receiver
My favorite style was the Collins 75a series I use a 75A4, which is often bashed by the AM folks, but I find it to be about the best receiver I have ever tried. If I find a truly superior receiver to the A4, I'll retire mine and change over to that. The main deficiency of the A4 is the audio. I use an outboard AF amp (an old 50's vintage 10w hi-fi amplifier using a pair of 6V6's in pushpull). I changed the .01 mfd coupling caps in the low level audio stages of the receiver to 0.1. Actually, I just bridged the .1's across the originals, to minimise melted plastic insulation on the wiring in the receiver. I pulled out the original 6AQ5 to save unnecessary drain on the power supply and to reduce heat generation. I also clipped out a couple of 510 pf mica caps that were added in later models to attenuate the high frequency response. From the diode detector to the audio output, the frequncy response is now almost flat from 30~ to about 5000~. On one of my A4's I added an outboard box with additional mechanical filters. The stock 3 selectivities is not enough if you want cw, ssb plus optimum AM under a variety of band condx. Don K4KYV _ Want to check if your PC is virus-infected? Get a FREE computer virus scan online from McAfee. http://clinic.mcafee.com/clinic/ibuy/campaign.asp?cid=3963
RE: [AMRadio] FW: Homebrew receiver
Don, ...the Scott had push pull 25L6 (6L6 with 25 volt filaments), ... The tube is a beam power tetrode like the 6L6, but two are quite different. The 25L5, 35L6 and 50L6 were designed for ac/dc radios, they are physically much smaller and have nowhere near the scrote of a 6L6. They are more like a 6V6 than a 6L6. A later miniature version is the 50C5, which is similar to a 6AQ5. Thanks for pointing that out, I never looked up the tube, and assumed it was just like a 6L6! The Scott only runs about 120 volts on things, so power output is low, but its very clean, about 3 watts likely. I have a Scott SLRM with pushpull 25L6's, and it sounds very good on AM. It is not a real communications receiver, though. It is more like a high quality late 1930's broadcast radio. Most of the precision technology went into careful shielding to prevent the local oscillator from radiating. The rx was used on board the Liberty Ships during WWII as an entertainment radio. They didn't want the enemy to home on the signal from the oscillator and discover the location of the ship. I knew it was designed to prevent anything radiating out of the receiver. They really went to extreme methods to prevent any LO radiation, completely closed cabinet, not even a single vent hole, total shielding between the rf coils in the RF amp, etc. I knew it was designed just before WW2, and also knew it was designed for use on ships, but I did not know about the liberty ships. Its only real drawback is the frequency resolution, the stability is very good, the noise is very low, good bandwidth choices. I had problems with the magic eye tube, it was too dim till I increased the voltage to it...I think I built a little separate high voltage supply and got the plate voltage up to 200 volts, and the tube is nice and bright. The mixer design they used looks very interesting, and works very well. Its a pentode, and they use one grid for rf, another for the LO injection. I have not seen that circuit design in any of the handbooks or other receivers, they use multigrid converter tubes (4 grids) which are very noisy, or use tubes with 3 grids but inject the LO into the rf grid or the cathode circuit, not another grid like the Scott. The circuit Scott used seems to be very quiet, but isolates the LO very well from the tuned circuits in the mixer RF input. The Scott I have is just like new,, and in 10 years or so has not had a single problem other than the dim magic eye tube. Radio shack made a good foam suspension speaker with wizzer cone that fits in, and sounds very good! Another great thing about the Scott SLRM is that both 80 and 40 meters are on the same band (2). Tuning is a little touchy, but no band changing between 80 and 40 meters! Its quite a good receiver for AM when things are not crowded, and when the band is packed, I don't want to listen anyway, too much of a chore on any receiver. Its nice to use when hanging around the shack building things, a real fine sounding classic! Brett N2DTS Don K4KYV _ Add MSN 8 Internet Software to your current Internet access and enjoy patented spam control and more. Get two months FREE! http://join.msn.com/?page=dept/byoa ___ AMRadio mailing list AMRadio@mailman.qth.net http://mailman.qth.net/mailman/listinfo/amradio
RE: [AMRadio] FW: Homebrew receiver
The Hallicrafters SX-28 has the finest AM sound I have ever heard in a commercial or military general coverage receiver. 8 watts from PP 6v6's and that bass boost switch! OOHH!!! Rockin' to the oldies!
Re: [AMRadio] FW: Homebrew receiver
I think the SX-28 audio is pretty much the same as the SX-25. Superb!
RE: [AMRadio] FW: Homebrew receiver
Dave, I always loved the Collins receivers, but they were very poor for AM work, as I guess you know. When AM was in, the technology did not seem to support good filters, xtal filters were in, or low frequency IF stages, both had drawbacks for hi fidelity AM reception. When mechanical filters came out, the move to ssb was already in motion, so Collins concentrated on building a good ssb receiver for ham use. They were very successful. I don't think Collins ever designed a good audio output stage in anything they built, not like the direct coupled, push pull output amp like the Scott receivers had, or the hi power push pull output some of the Hallicrafters receivers used. They were not alone, and the best sounding audio receivers were built at a time when some of them were used as hi fidelity amplifiers for other things, my Scott has a phono input... The Collins receivers could be upgraded easy these days, with an add on low distortion AM detector, and good filters, into an outboard audio amp. Anything that uses a 455Khz IF frequency can be upgraded quite a bit with the kiwi filters, you can tack on a new detector without any trouble, and all the Collins receivers were very accurate in frequency, very stable, with good frequency resolution. One of these days, I will get around to upgrading a 75S1 for hi fidelity AM reception. Those receivers are still quite reasonable in price, and nice and small. I had one some time ago, but sold it. On AM, it was as broad as a barn door, but I did not know about the kiwi filters then. Way back, when receivers like the NC303 were at fests for $50.00, I don't think you could come up with anything better for AM reception. Some older radios had better fidelity, but had poor (or no) frequency resolution, poor bandwidth shape factors, and other problems. I think only the R390 with outboard audio was in the ball park. Its quite surprising that the NC300/303 still sells for a reasonable price these dayswhen you see them, they are well under the cost of something like a 75a4. Once and a while, I see them for $200.00 or less. That is a lot of receiver for the price! Brett N2DTS -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of David Knepper Sent: Friday, October 17, 2003 8:21 AM To: amradio@mailman.qth.net Subject: Re: [AMRadio] FW: Homebrew receiver Very fine, Brett. In all the receivers that I have at the Collins Radio Center, I like the NC-303, the best for AM Dave, W3ST Secretary to the Collins Radio Association Publisher of the Collins Journal www.collinsra.com
Re: [AMRadio] FW: Homebrew receiver
Thanks, Brett for these delightful thoughts on receivers. Very informative. Dave, W3ST Secretary to the Collins Radio Association Publisher of the Collins Journal www.collinsra.com - Original Message - From: Brett Gazdzinski [EMAIL PROTECTED] To: amradio@mailman.qth.net Sent: Friday, October 17, 2003 9:02 AM Subject: RE: [AMRadio] FW: Homebrew receiver Dave, I always loved the Collins receivers, but they were very poor for AM work, as I guess you know. When AM was in, the technology did not seem to support good filters, xtal filters were in, or low frequency IF stages, both had drawbacks for hi fidelity AM reception. When mechanical filters came out, the move to ssb was already in motion, so Collins concentrated on building a good ssb receiver for ham use. They were very successful. I don't think Collins ever designed a good audio output stage in anything they built, not like the direct coupled, push pull output amp like the Scott receivers had, or the hi power push pull output some of the Hallicrafters receivers used. They were not alone, and the best sounding audio receivers were built at a time when some of them were used as hi fidelity amplifiers for other things, my Scott has a phono input... The Collins receivers could be upgraded easy these days, with an add on low distortion AM detector, and good filters, into an outboard audio amp. Anything that uses a 455Khz IF frequency can be upgraded quite a bit with the kiwi filters, you can tack on a new detector without any trouble, and all the Collins receivers were very accurate in frequency, very stable, with good frequency resolution. One of these days, I will get around to upgrading a 75S1 for hi fidelity AM reception. Those receivers are still quite reasonable in price, and nice and small. I had one some time ago, but sold it. On AM, it was as broad as a barn door, but I did not know about the kiwi filters then. Way back, when receivers like the NC303 were at fests for $50.00, I don't think you could come up with anything better for AM reception. Some older radios had better fidelity, but had poor (or no) frequency resolution, poor bandwidth shape factors, and other problems. I think only the R390 with outboard audio was in the ball park. Its quite surprising that the NC300/303 still sells for a reasonable price these dayswhen you see them, they are well under the cost of something like a 75a4. Once and a while, I see them for $200.00 or less. That is a lot of receiver for the price! Brett N2DTS -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of David Knepper Sent: Friday, October 17, 2003 8:21 AM To: amradio@mailman.qth.net Subject: Re: [AMRadio] FW: Homebrew receiver Very fine, Brett. In all the receivers that I have at the Collins Radio Center, I like the NC-303, the best for AM Dave, W3ST Secretary to the Collins Radio Association Publisher of the Collins Journal www.collinsra.com ___ AMRadio mailing list AMRadio@mailman.qth.net http://mailman.qth.net/mailman/listinfo/amradio
Re: [AMRadio] FW: Homebrew receiver
Brett and others, I wonder if we could somewhat emulate the same results as you had by eliminating the RF stage from let us say a NC-300 receiver and go directly into the mixer stage. I am sure that this has been tried before for operation on 160 and 80 meters. Just a thought that is not so original. Thank you. Dave, W3ST Secretary to the Collins Radio Association Publisher of the Collins Journal www.collinsra.com - Original Message - From: Brett Gazdzinski [EMAIL PROTECTED] To: amradio@mailman.qth.net Sent: Wednesday, October 15, 2003 8:46 PM Subject: [AMRadio] FW: Homebrew receiver This is what I plan on sending to Electric Radio, along with pictures. What do you guys think? Brett N2DTS I wanted a complete home brew station, and since I have a homebrew pair of 813,s, modulated by one of two modulator decks, push pull parallel 100TH,s, or a pair of 4sc250b,s, and a classic push pull rig with link coupling, using 812,s modulated by a pair of 811,s, only a receiver was needed. At first, I thought I would build something simple that worked just well enough to be able to copy AM under good conditions, just so I could say I had a home brew station. But I wanted something a little better than the regen receiver type of radio, maybe a simple superhetrodyne. I did loads of research, looked in Bill Orr, and all my old ARRL handbooks, looking for simple receivers. All the circuits had some sort of problem, complex tapped coils, hard to get parts, poor designs, etc. I also looked at the diagrams for things like my Gonset G76, the Scott model SLRM I have, the Hallicrafters sx17, and the R390. I decided to base the receiver on the Scott SLRM, since it works very well, has good fidelity, uses 8 pin tubes and a 455Khz IF. I ran into problems though, as the Scott was built to reduce emissions out the antenna, with loads of shielding and an rf amp with tuned circuits. I accumulated parts, and started construction with the basic layout of two tuned circuits on the antenna input, an RF amp, a separate local oscillator and mixer, two stages of IF amplification, hifi detector, s meter circuit, agc circuit, and power supply. Since it was to be experimental, I used octal sockets for everything, the antenna coils, the local oscillator coils, and the IF transformers. The receiver started out with plug in coils to change bands. I laid out all the parts, leaving room between things to allow room for experimentation, and mounted the basic parts. I tried various circuits for the local oscillator, using coils wound on ceramic forms, B+W coil stock, and slug tuned ceramic coil forms. This step would have been very difficult without the aid of a very nice spectrum analyzer I have through work. It allowed me to look at the frequency output, harmonics, hash, drift, frequency range, amplitude, all at the same time. At first, I went with plug in coils in the local oscillator, used the rf amp, using the spectrum analyzer to peak things and check gain. The mixer was easy, then to a filter. I planed on using a mechanical filter, but they are expensive, and a little tricky to put in the circuit. I found a company on the web, kiwi, who makes various filters, and went with one that has an op amp input, three filters of slightly different center frequencies (sets bandwidth) and an op amp output, and runs off 10 to 30 volts dc. There is no loss through the filter, and its quite similar in results to a mechanical filter. I used a 5.5kc model. It mounts on Velcro, and has pig tail shielded wires to hook up to the IF system. This filter is easy to add to any receiver using 455 KHz as an IF, and really works fantastic. I copied the IF system out of the Scott, and used a hifi detector on one of the AM web pages. It took some experimentation to get the agc takeoff and IF gain control systems working well, then I added the S meter circuit I stole out of the Bill Orr handbook using a 6SN7. Taking the receiver for a test drive revealed problems. Startup drift was excessive, muting the receiver seemed impossible, the RF amp caused all sorts of problems, and the if amps were unstable. As a test, I hooked the antenna up to the mixer input, and bypassed the rf amp, and had very good results, so I removed the rf amp completely, and went with two tuned circuits then into the mixer. Some experimentation with the antenna link on the input coil boosted gain quite a bit. I ordered a selection of NPO caps, and did weeks of experimentation on the local oscillator stability, changing components, design, putting the coil in a metal plug in can to shield it, and got the stability much better, but still have startup drift for the first 5 minutes. Careful shielding and reducing the gain of the IF eliminated the odd oscillations I got at times, and the receiver was working quite well. I
RE: [AMRadio] FW: Homebrew receiver
Dave, Many receivers did just that. I don't remember if the NC300/303 used the rf amp on the low bands or not. The NC300/303 was one of the best AM receivers I ever had. I think it needed better audio stages, but I always used a detector output. Frequency resolution and stability were very good, bandwidth choices were good, although I don't remember how sharp the filters were. The looks of the thing were quite Art Deco, and did not turn everyone on, but they are very good receivers in my book. Hard to mount one in a rack though, with the rounded corners. I am not sure how much the RF amp adds to the noise level. A well designed rf amp section can actually reduce noise levels. Noise mostly comes from mixers, and overall tube counts. All mixers add some noise, some designs are much better than others, and the more there are, the more noise you get. I used single conversion, with a quiet mixer setup, and used two tuned circuits of very high Q in the input, along with resonant dipole antennas for 80 and 40 meters, so I don't get any images or other problems, as signals out of band are attenuated very much before making it to the mixer. This is not always the case in the general receiver setup, as many bands are covered, low Q broad band coils are used, and who knows what antenna will be used. As far as the NC303/300 goes, if you can get past the style, the only big improvement to be done would be the audio output (if used), and maybe the addition of a KIWI filter module. These are quite like mechanical filters, very sharp. One of those would be very easy to add, without hacking up the receiver. Brett N2DTS -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of David Knepper Sent: Thursday, October 16, 2003 4:31 AM To: amradio@mailman.qth.net Subject: Re: [AMRadio] FW: Homebrew receiver Brett and others, I wonder if we could somewhat emulate the same results as you had by eliminating the RF stage from let us say a NC-300 receiver and go directly into the mixer stage. I am sure that this has been tried before for operation on 160 and 80 meters. Just a thought that is not so original. Thank you. Dave, W3ST Secretary to the Collins Radio Association Publisher of the Collins Journal www.collinsra.com - Original Message - From: Brett Gazdzinski [EMAIL PROTECTED] To: amradio@mailman.qth.net Sent: Wednesday, October 15, 2003 8:46 PM Subject: [AMRadio] FW: Homebrew receiver This is what I plan on sending to Electric Radio, along with pictures. What do you guys think? Brett N2DTS I wanted a complete home brew station, and since I have a homebrew pair of 813,s, modulated by one of two modulator decks, push pull parallel 100TH,s, or a pair of 4sc250b,s, and a classic push pull rig with link coupling, using 812,s modulated by a pair of 811,s, only a receiver was needed. At first, I thought I would build something simple that worked just well enough to be able to copy AM under good conditions, just so I could say I had a home brew station. But I wanted something a little better than the regen receiver type of radio, maybe a simple superhetrodyne. I did loads of research, looked in Bill Orr, and all my old ARRL handbooks, looking for simple receivers. All the circuits had some sort of problem, complex tapped coils, hard to get parts, poor designs, etc. I also looked at the diagrams for things like my Gonset G76, the Scott model SLRM I have, the Hallicrafters sx17, and the R390. I decided to base the receiver on the Scott SLRM, since it works very well, has good fidelity, uses 8 pin tubes and a 455Khz IF. I ran into problems though, as the Scott was built to reduce emissions out the antenna, with loads of shielding and an rf amp with tuned circuits. I accumulated parts, and started construction with the basic layout of two tuned circuits on the antenna input, an RF amp, a separate local oscillator and mixer, two stages of IF amplification, hifi detector, s meter circuit, agc circuit, and power supply. Since it was to be experimental, I used octal sockets for everything, the antenna coils, the local oscillator coils, and the IF transformers. The receiver started out with plug in coils to change bands. I laid out all the parts, leaving room between things to allow room for experimentation, and mounted the basic parts. I tried various circuits for the local oscillator, using coils wound on ceramic forms, B+W coil stock, and slug tuned ceramic coil forms. This step would have been very difficult without the aid of a very nice spectrum analyzer I have through work. It allowed me to look at the frequency output, harmonics, hash, drift, frequency range, amplitude, all at the same time. At first, I went with plug in coils in the local oscillator, used the rf amp, using
RE: [AMRadio] FW: Homebrew receiver
As far as the NC303/300 goes, if you can get past the style, the only big improvement to be done would be the audio output (if used), and maybe the addition of a KIWI filter module. These are quite like mechanical filters, very sharp. One of those would be very easy to add, without hacking up the receiver. Not everyone will agree with you on the style issue ... I like it! Unless KIWI has started making filters at 80 Khz, this isn't an option. The 303 is 2Khz wide in the SB1/2 positions, and has 3.5 and 8Hhz positions for AM. Skirt selectivity is pretty typical of the L/C IF arrangement. The downsides I've found in both the 300 and 303 include BCB feedthrough on 80 (solved by using a KIWI BC reject filter in the antenna lead), and SWBC feedthrough on 20M at night. There's an internal tunable trap to null that out, but it isn't terribly effective. Same in the 300 - - although for some reason the 303 manual doesn't say anything about it even though it's in there. Grant/NQ5T
RE: [AMRadio] FW: Homebrew receiver
I sent the article in today. There has been a lot of talk about the ham radio hobby dying, and I would say its so except for the AM crowd. I can not see many young kids getting all fired up about radio like I was as a kid. I really got bit hard by the bug, and started building stuff when I was about 14. I actually got into ham radio at age 16, and started building radio stuff around then. Some stuff even worked. I remember finding the sears repair dumpster, a gold mine for electronics parts! Modern rigs just don't do anything for me, and even commercial older tube type ham rigs disappoint me, they were mostly quite poor in design with marginal components, at least for any sort of fidelity. You can still buy kits, mostly qrp rigs, and I built one that works surprisingly well (on CW), but IC chips just are not as fun as tube stuff. I was lucky that I bought loads of stuff when people were giving it away at fests, both the full range of tube ham gear, and good parts. I plan on building more, lower power transmitters with built in VFO and modulator, and maybe even a receiver built in. Sort of like a home brew Gonset G76, only Hi Fidelity. The only real enthusiasm I see on ham radio is on AM, restoring the old stuff, modifying the new stuff, home brew, and the QRP guys running kits on low power CW. The rest seems to be a bunch of very old farts just talking, like people do on the phone. There is no reason you cant build things, it just takes a bit of time to get all the parts, but you CAN get them. Brett N2DTS -Original Message- From: Mark J. Giubardo [mailto:[EMAIL PROTECTED] Sent: Thursday, October 16, 2003 11:08 AM To: [EMAIL PROTECTED] Subject: RE: [AMRadio] FW: Homebrew receiver Hi Brett, Just one comment from me. ITS GREAT! I can hardly wait to see it in ER with pictures! I am sure they will publish this as it is both interesting and well written in my opinion. Thanks for sharing your experiences...reminds me of the way HAM radio used to be! 73's, Mark W1MJG -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of Brett Gazdzinski Sent: Wednesday, October 15, 2003 8:46 PM To: amradio@mailman.qth.net Subject: [AMRadio] FW: Homebrew receiver This is what I plan on sending to Electric Radio, along with pictures. What do you guys think? Brett http://mailman.qth.net/mailman/listinfo/amradio
RE: [AMRadio] FW: Homebrew receiver
Yes, its been quite some time since I had the NC300 and NC303! No 455Khz IF at all? 80 KHz is quite low, and should do real well in the IF, but its not easy to get the mechanical filter shape out of tuned circuits, they tend to be pointy at the top. My G76 uses a 262Khz IF, and it works quite well, but they used resistors across the IF transformers to lower the Q, and small caps from primary to secondary to shape the response. Quite a good receiver except for the fidelity. I added a small 4 watt IC chip audio amp, replacing the modulator driver/audio output setup they used, and get quite good fidelity. Its easy to change the receive bandwidth, increase the resistor value makes it sharper, as does removing the little caps from primary to secondary. The shape is another matter... The transmit audio is a bit hopeless, small iron, sweep tubes as modulators (in some crazy triode connection using the screens as grids), but feedback helps. Got to love the dial on the NC300/303, what a nice piece of work that was. Quite a good receiver now, great in its day. My favorite style was the Collins 75a series, 32v series, the kwm2 type look, and the Hallicrafters SX17/SX28 type look. I think the Gonset G76 also looked very sharp, one of the few Gonset things that looked nice, some was quite odd. I always had a thing for the TMC GPR90, thought it looked quite nice, but never had one. One project that I have not go to yet is to get a 75s1 and do it up for AM. A hi fidelity detector, external audio amp, and a KIWI filter in place of the back to back IF cans would give you a stable, accurate, reliable, small good sounding receiver. Brett N2DTS -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of Grant Youngman Sent: Thursday, October 16, 2003 11:06 AM To: amradio@mailman.qth.net Subject: RE: [AMRadio] FW: Homebrew receiver As far as the NC303/300 goes, if you can get past the style, the only big improvement to be done would be the audio output (if used), and maybe the addition of a KIWI filter module. These are quite like mechanical filters, very sharp. One of those would be very easy to add, without hacking up the receiver. Not everyone will agree with you on the style issue ... I like it! Unless KIWI has started making filters at 80 Khz, this isn't an option. The 303 is 2Khz wide in the SB1/2 positions, and has 3.5 and 8Hhz positions for AM. Skirt selectivity is pretty typical of the L/C IF arrangement. The downsides I've found in both the 300 and 303 include BCB feedthrough on 80 (solved by using a KIWI BC reject filter in the antenna lead), and SWBC feedthrough on 20M at night. There's an internal tunable trap to null that out, but it isn't terribly effective. Same in the 300 - - although for some reason the 303 manual doesn't say anything about it even though it's in there. Grant/NQ5T ___ AMRadio mailing list AMRadio@mailman.qth.net http://mailman.qth.net/mailman/listinfo/amradio
Re: [AMRadio] FW: Homebrew receiver
Modern rigs just don't do anything for me, and even commercial older tube type ham rigs disappoint me, they were mostly quite poor in design with marginal components, at least for any sort of fidelity. One thing we tend to forget when criticizing commercial gear is that it must meet economic design criteria, be repeatable without undue work and perform without unacceptable consequences. Design engineers could do as you have Brett, but I don't think many people could afford the finished product. What you have is a one of a kind receiver that meets your specifications but maybe not other people's expectations. Design criteria must cross many requirements in the commercial market in order to be successful. Thank goodness the government bought many examples of the gear we cherish or we may not have the opportunity to possess them today. There is not a piece of equipment out there today that meets everyone's expectations or can not be modified to appease an individual. But the NC 300/303 is a good piece of gear as is the Globe King 400/500 series of transmitters by WRL. One must do as you have, decide what you want improved and accomplish the task themselves. You have done an admirable job with your project, but I wouldn't spend that much time on it. Hope to read your article. By the way, if you care to contact him, K5AM, Mark Mandelkern started a project such as yours back in 1990. He has a block diagram posted on QRZ when you look up his call sign. He also has a website which contains more information. You will find he is a very nice person who will share information readily if you care to contact him. http://www.zianet.com/k5am/ 73 Jim de W5JO
RE: [AMRadio] FW: Homebrew receiver
Jim, I don't forget that all the commercial stuff was built with cost and profit in mind, I can well understand the restrictions they faced when designing and building it. That is mostly why I did not keep the stuff around, it was too much of a compromise. Many people would not like my stuff as it tends to be quite large for its power output. My 300 watt push pull rig (globe king 400 copy?) is three times the size of the globe king. My mod transformer likely weighs more than the entire glob king! Hardly the thing when you are tight on space, or have a bad back... Collins was close, they made some big and heavy rigs. I had a 30K1, and a KWS-1, both quite robust, as is the 32v series. All those rigs were 100% reliable, and I still have two 32v3,s, which continue to run like Swiss watches. None of that stuff was affordable by many when it was built! Brett N2DTS One thing we tend to forget when criticizing commercial gear is that it must meet economic design criteria, be repeatable without undue work and perform without unacceptable consequences. Design engineers could do as you have Brett, but I don't think many people could afford the finished product. What you have is a one of a kind receiver that meets your specifications but maybe not other people's expectations. Design criteria must cross many requirements in the commercial market in order to be successful. Thank goodness the government bought many examples of the gear we cherish or we may not have the opportunity to possess them today. There is not a piece of equipment out there today that meets everyone's expectations or can not be modified to appease an individual. But the NC 300/303 is a good piece of gear as is the Globe King 400/500 series of transmitters by WRL. One must do as you have, decide what you want improved and accomplish the task themselves. You have done an admirable job with your project, but I wouldn't spend that much time on it. Hope to read your article. By the way, if you care to contact him, K5AM, Mark Mandelkern started a project such as yours back in 1990. He has a block diagram posted on QRZ when you look up his call sign. He also has a website which contains more information. You will find he is a very nice person who will share information readily if you care to contact him. http://www.zianet.com/k5am/ 73 Jim de W5JO ___ AMRadio mailing list AMRadio@mailman.qth.net http://mailman.qth.net/mailman/listinfo/amradio
[AMRadio] FW: Homebrew receiver
This is what I plan on sending to Electric Radio, along with pictures. What do you guys think? Brett N2DTS I wanted a complete home brew station, and since I have a homebrew pair of 813,s, modulated by one of two modulator decks, push pull parallel 100TH,s, or a pair of 4sc250b,s, and a classic push pull rig with link coupling, using 812,s modulated by a pair of 811,s, only a receiver was needed. At first, I thought I would build something simple that worked just well enough to be able to copy AM under good conditions, just so I could say I had a home brew station. But I wanted something a little better than the regen receiver type of radio, maybe a simple superhetrodyne. I did loads of research, looked in Bill Orr, and all my old ARRL handbooks, looking for simple receivers. All the circuits had some sort of problem, complex tapped coils, hard to get parts, poor designs, etc. I also looked at the diagrams for things like my Gonset G76, the Scott model SLRM I have, the Hallicrafters sx17, and the R390. I decided to base the receiver on the Scott SLRM, since it works very well, has good fidelity, uses 8 pin tubes and a 455Khz IF. I ran into problems though, as the Scott was built to reduce emissions out the antenna, with loads of shielding and an rf amp with tuned circuits. I accumulated parts, and started construction with the basic layout of two tuned circuits on the antenna input, an RF amp, a separate local oscillator and mixer, two stages of IF amplification, hifi detector, s meter circuit, agc circuit, and power supply. Since it was to be experimental, I used octal sockets for everything, the antenna coils, the local oscillator coils, and the IF transformers. The receiver started out with plug in coils to change bands. I laid out all the parts, leaving room between things to allow room for experimentation, and mounted the basic parts. I tried various circuits for the local oscillator, using coils wound on ceramic forms, B+W coil stock, and slug tuned ceramic coil forms. This step would have been very difficult without the aid of a very nice spectrum analyzer I have through work. It allowed me to look at the frequency output, harmonics, hash, drift, frequency range, amplitude, all at the same time. At first, I went with plug in coils in the local oscillator, used the rf amp, using the spectrum analyzer to peak things and check gain. The mixer was easy, then to a filter. I planed on using a mechanical filter, but they are expensive, and a little tricky to put in the circuit. I found a company on the web, kiwi, who makes various filters, and went with one that has an op amp input, three filters of slightly different center frequencies (sets bandwidth) and an op amp output, and runs off 10 to 30 volts dc. There is no loss through the filter, and its quite similar in results to a mechanical filter. I used a 5.5kc model. It mounts on Velcro, and has pig tail shielded wires to hook up to the IF system. This filter is easy to add to any receiver using 455 KHz as an IF, and really works fantastic. I copied the IF system out of the Scott, and used a hifi detector on one of the AM web pages. It took some experimentation to get the agc takeoff and IF gain control systems working well, then I added the S meter circuit I stole out of the Bill Orr handbook using a 6SN7. Taking the receiver for a test drive revealed problems. Startup drift was excessive, muting the receiver seemed impossible, the RF amp caused all sorts of problems, and the if amps were unstable. As a test, I hooked the antenna up to the mixer input, and bypassed the rf amp, and had very good results, so I removed the rf amp completely, and went with two tuned circuits then into the mixer. Some experimentation with the antenna link on the input coil boosted gain quite a bit. I ordered a selection of NPO caps, and did weeks of experimentation on the local oscillator stability, changing components, design, putting the coil in a metal plug in can to shield it, and got the stability much better, but still have startup drift for the first 5 minutes. Careful shielding and reducing the gain of the IF eliminated the odd oscillations I got at times, and the receiver was working quite well. I did not like the tuning dials I had, marking the frequency was hard with the drift, and I have a real problem marking the frequency so it looks nice on the dial. I needed something better, and found the almost all digital electronics digital frequency readouts, basically a frequency counter with a selectable frequency offset. You program the thing to offset the IF frequency, in my case, 455Khz lower, and all you need to do is get the pickup close to the local oscillator tube, and the display reads the exact receive frequency down to 1000 Hz. I used their backlit display, which looks nice, and a real accurate frequency readout is very nice
