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20131130 0514UTC 14009.9kHz ZS1ZC
Date : 30/Nov/2013 0514UTC
Freq : 14009.9kHz CW
Rig : SDR(PI4THT)
ANT : Mini-Whip(PAØRDT)
PC recording
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Licensed since 1982. Major interest is in HF. Rig is Yaesu FT-101ZD and Kenwood TS-830S, 400W homebrew linear, antennas are inverted Vee for 30/40/80m, homebrew "Silver Spider" Spiderbeam for 10-20m. Beam is at 15m height. VHF/UHF is FT-897D with interleaved 2m/70cm yagis.
See here for photos of antenna, rotator and tower. You can get the manuals for construction of the Silver Spider here and here.
QSL Info: Via Buro, QRZ.COM, LOTW or via eQSL.
Electronic engineer by training, telecomms programme manager by experience.
You can contact me at zs1zc.za@gmail.com
The Antenna
March 2011: The ZS1ZC Silver Spider is up! This a variant on the original Spiderbeam design. What makes Spiderbeam unique is that they're happy to have you build your own without getting the parts from them. They will even provide you with the free construction guide here.
So what makes the Silver Spider unique? You'll notice that Spiderbeam use fibreglass spreaders in a symmetrical cross formation, lashed together, to provide tie-points for the various wire elements. When I investigated fibreglass suppliers in Cape Town their tubes were either too expensive or the wrong size. So I made two observations:
1. The booms of most symmetrical antennas like yagis are invariably metal, and the parasitic elements are often mounted directly on them. How can this be? It's because the centre points of the parasitic elements are at low impedance, and therefore a direct connection between them has no effect on performance. So the front-to-back spreader could be replaced by a similar sized (and cheaper!) aluminium tube.
2. The 20m driven element is almost as long as the left-to-right spreader. This means that the 20m DE could be replaced by an aluminium tube like the boom. I ran simulations on 4NEC2 and found that using a 30mm tube required a slightly shorter element, but the solution worked. In other words, the end of the 20m DE would serve the same purpose as the end of the spreaders for holding the shorter, higher-frequency wire elements in place.
How did it perform? Well, the middle picture below is a simulation of the original "classic" Spiderbeam (dimensions based on their literature), and the right-hand one is the Silver Spider (so-called because the "spreaders" are now metal). The radiation patterns are very similar, but the 20m performance of the Silver Spider shows improved front-to-back ratio (not by much in practice). The situation is reversed on other bands, yet the gain remains within a dB or so of the original. I designed and built it for 20m, 15m and 10m, but in principle it can be extended to cover the intervening WARC bands too. I've found this antenna to be very effective in actual use, providing significant gain over my inverted vee as expected. It also seems to have quite deep front-to-side nulls which is nice.
The important thing is that construction is performed exactly as Spiderbeam specify in terms of the main structure - only the relative lengths and positions of the wire elements change.
The Receiver
October 2011: Just picked up a bargain on an FRG-7 down at the local amateur club. Needs a tune-up with some test kit to get her running better than I can with only a screwdriver, but what a beauty of a radio. First task was to replace the IF filter with a narrower Murata version, this has made a great difference. I've put in a red/green LED for the Lock indicator, and replaced all the filament bulbs with clear LEDs. The clear-white look in the dials is almost eerie, but gives a great impression.
I grew up with one of these in the family - welcome home, sweetheart! You're a classic.
The Real Deal
April 2012: Now we're cookin' - the new addition to the shack is an FT-101ZD MkII. I'm the third owner. What a beauty! She shrieks like a banshee with the full 140W on 20m and 100W on 10m - nothing wrong with those finals. Having been an 897D man for the past four years, this is quite an experience. Way back in '82 when I got my licence, I had a TS120S which is also a knobs-and-dials rig. Compared to the menus and buttons of the 897D the 101ZD is like coming home again. It has subtleties like being able to tune through the 100Hz step continuously (analogue VFO), rather than the discrete steps of the 897D. The channel width control is right there on the panel, not buried away in the menus. Same with RF power, mic gain etc. The warm-up frequency drift, lack of electronic keyer, absent digital interface and no communications receiver are small sacrifices - besides, I have those on another shelf.
I had more unsolicited "great-audio" reports in the first weekend than I have in four years on the 897D. Also, the receiver just seems to come alive compared to the DSP-based younger brother. I've always believed that if you can hear band noise your receiver is sensitive enough - I can do that with both these rigs, but the 101ZD just seems to provide a more signal-filled band. I can only assume that if the 897's noise figure is decent, the 101ZD's is simply better. Receive audio is excellent too. Still have to use it in crowded bands, but if there's any problem with intermod I'll consider putting in a Mini-Circuits double balanced mixer to help things along.
Tuning the finals for each band is easy, and you get the feeling with tube rigs that you really are tweaking the insides - wideband transistor transceivers don't have that. Even after thirty years, the tuning dial feels like it's suspended in oil it's so smooth and light. And then there's the smell. Nothing has the scent of a tube transceiver when she's hot! When I was a kid, a local ham had Heathkits wall-to-wall and the smell of warming glass, bakelite and dust is unmistakable.
I've read plenty of reviews of this and other rigs from this era where the reviewer regrets having sold it - I think this one is a keeper.
The Amplifier
February 2013: I've spent the last two months on-and-off working on a linear. I got fed up with only having 100W on HF - and besides, my licence allows 400W, which is 6dB or one full S-point difference. That doesn't amount to much on a clear band, but at the noise threshold or in the presence of QRM, 6dB is significant.
So I asked around locally if anyone had the main parts - I managed to get a TB3-750 triode, a few doorknobs and a 1500-0-1500V transformer that's built like a tank. Sundries like vacuum relays and a Pi-L coil came from a local collector, as did a filament transformer (this tube needs 5V at 14A, which is a little unusual). That left me with the air variable capacitors for the output network. Importing those would be in the €100 region for each, so I decided to build my own.
You can get nice little capacitor design utilities on the web. I calculated the required plate size and quantity, got some aluminium plate and started cutting and filing - this is not for anyone who isn't patient - and a few weeks later I had working caps.
As for the design, the basic triode-based linear amp is pretty standard, but I got design details from Frits, PAØFRI here; he does a great job of a generic triode amplifier that supports a variety of different tubes. While I didn't copy his circuit exactly, his schematic is pretty accurate (below).
Another site that was really useful was Bob, WB0NNI, whose website is here. There's plenty of background reading available on the web, and if you're in Europe or the US, plenty of resources and surplus dealers where you can get used or NOS (New-Old-Stock) tubes and other tricky components.
Anyway, the main thing is, the amp's up and running, delivering around 400W PEP on 20m with some ease. Getting the output network right is proving difficult, ensuring that each capacitor has enough swing to get the required peak. I reckon they have too much base capacitance (when fully open), and combined with extra neutralization in the anode circuit, there seems to be too much inductance floating around too - bottom line is that tuning up higher than 15m is not happening. So for the moment this baby is going to be in service for 20m to 80m.
If you're interested in a linear, I'd highly recommend building one - just keep that spare hand in your pocket if you're doing a tube design because of the high voltages. You may well end up paying more than for a used oldie like the FL2100Z, but the experience is what counts. Alternatively, you may want to go semiconductor, which is a totally different design philosophy. You'll be doing plenty of circuit and PCB design, whereas for a tube design there's more hardware and metalwork required.
Has it performed for me? Inevitably the evidence is anecdotal, but so far so good - I've had some great signal reports in the last few days, which is encouraging. Perhaps a few A/B tests and getting the feel of using it will prove its value.
The Full Shebang
May 2013: Finally, the chance has come to get a classic onto the shelf in the shack. I took up an offer on the wall-to-wall suite of the Kenwood TS-830S. If you don't know this beauty, she's one of the last hybrids (semiconductor rig with tube driver and finals) from the 1980's, a similar vintage to the FT-101ZD. The picture shows the basic transceiver, the external speaker and the external VFO (VFO-230), but I also got the original microphone, the antenna tuner (AT-230) and the station monitor (SM-220) - the full package. And not only that - it turned out to be the Gold Label version with all the filters still in situ.
This has to be one of the most elegant transceivers ever made. Yaesu took the Collins look and standardized it, but Kenwood somehow did an Apple-style design leap and produced a machine that is functionally beautiful as well as aesthetically very pleasing. Everything seems to be in a place on the front panel that was designed for it. While some of the controls are small, they're not flimsy, and the main switches have a solid feel enhanced by the thick metal-feel front panel. Where Yaesu gave us the style of a rockstar, Kenwood produced a smoky, demure screen goddess. Check out the transceiver reviews on eham.net - you'll see that she's in the top half dozen or so transceivers of all time, and final preference is usually a matter of brand loyalty. I love the FT-101ZD, but in the TS-830S I have a soulmate. Sorry, Icom, I could never get my head around your look - I just wasn't that into you!
Now this lady is 35 years old, and I'm still getting to know her creaks and crackles, but physically she's in very good cosmetic condition inside and out. There seem to be a few functional problems that I need to sort out, like an intermittent receiver, so a full service is what's needed here - this is going to be a pleasure!
Well, so far so good - the receiver intermittency seems to have been because the connectors to the RF board needed reflowing with a soldering iron. The input connector appears to have been dry-jointed, to the extent that removal of the female from the connector assembly caused the entire male section to come out of the printed circuit board, leaving neat little holes in the solder mounds on the underside of the pcb. So that problem seems to be fixed. It was a bit of a mission to remove the RF board from the rig, but you can get great instructions from Ken, K4EAA. He does a complete refurbishment service for US-based Kenwood hybrid owners, and also provides hard-to-get Kenwood parts. He also gives an excellent guide to getting the RF board out and replacing broken mechanical couplers. You can also get loads of info from Kenwood Hybrid Restoration.
The bandswitch is quite a sensitive area in these old rigs. Since they're pcb-based they're as open to the elements as any other part of the rig, so a good clean and lubrication is a good idea. It's also worthwhile looking into the bandswitch area, with a magnifying glass if necessary, to understand exactly how it moves, and how to get the correct wafer alignment when reassembling it. I didn't do this right the first time and ended up having to jockey the knob to get the right contacts to align. A quick resetting of the outer shaft and the coupler in the PA area fixed this nicely and gave the bandswitch the crisp firmness that it should have.
QSL Info: Via Buro, QRZ.COM, LOTW or via eQSL.
Electronic engineer by training, telecomms programme manager by experience.
You can contact me at zs1zc.za@gmail.com
The Antenna
March 2011: The ZS1ZC Silver Spider is up! This a variant on the original Spiderbeam design. What makes Spiderbeam unique is that they're happy to have you build your own without getting the parts from them. They will even provide you with the free construction guide here.
So what makes the Silver Spider unique? You'll notice that Spiderbeam use fibreglass spreaders in a symmetrical cross formation, lashed together, to provide tie-points for the various wire elements. When I investigated fibreglass suppliers in Cape Town their tubes were either too expensive or the wrong size. So I made two observations:
1. The booms of most symmetrical antennas like yagis are invariably metal, and the parasitic elements are often mounted directly on them. How can this be? It's because the centre points of the parasitic elements are at low impedance, and therefore a direct connection between them has no effect on performance. So the front-to-back spreader could be replaced by a similar sized (and cheaper!) aluminium tube.
2. The 20m driven element is almost as long as the left-to-right spreader. This means that the 20m DE could be replaced by an aluminium tube like the boom. I ran simulations on 4NEC2 and found that using a 30mm tube required a slightly shorter element, but the solution worked. In other words, the end of the 20m DE would serve the same purpose as the end of the spreaders for holding the shorter, higher-frequency wire elements in place.
How did it perform? Well, the middle picture below is a simulation of the original "classic" Spiderbeam (dimensions based on their literature), and the right-hand one is the Silver Spider (so-called because the "spreaders" are now metal). The radiation patterns are very similar, but the 20m performance of the Silver Spider shows improved front-to-back ratio (not by much in practice). The situation is reversed on other bands, yet the gain remains within a dB or so of the original. I designed and built it for 20m, 15m and 10m, but in principle it can be extended to cover the intervening WARC bands too. I've found this antenna to be very effective in actual use, providing significant gain over my inverted vee as expected. It also seems to have quite deep front-to-side nulls which is nice.
The important thing is that construction is performed exactly as Spiderbeam specify in terms of the main structure - only the relative lengths and positions of the wire elements change.
The Receiver
October 2011: Just picked up a bargain on an FRG-7 down at the local amateur club. Needs a tune-up with some test kit to get her running better than I can with only a screwdriver, but what a beauty of a radio. First task was to replace the IF filter with a narrower Murata version, this has made a great difference. I've put in a red/green LED for the Lock indicator, and replaced all the filament bulbs with clear LEDs. The clear-white look in the dials is almost eerie, but gives a great impression.
The Real Deal
April 2012: Now we're cookin' - the new addition to the shack is an FT-101ZD MkII. I'm the third owner. What a beauty! She shrieks like a banshee with the full 140W on 20m and 100W on 10m - nothing wrong with those finals. Having been an 897D man for the past four years, this is quite an experience. Way back in '82 when I got my licence, I had a TS120S which is also a knobs-and-dials rig. Compared to the menus and buttons of the 897D the 101ZD is like coming home again. It has subtleties like being able to tune through the 100Hz step continuously (analogue VFO), rather than the discrete steps of the 897D. The channel width control is right there on the panel, not buried away in the menus. Same with RF power, mic gain etc. The warm-up frequency drift, lack of electronic keyer, absent digital interface and no communications receiver are small sacrifices - besides, I have those on another shelf.
Tuning the finals for each band is easy, and you get the feeling with tube rigs that you really are tweaking the insides - wideband transistor transceivers don't have that. Even after thirty years, the tuning dial feels like it's suspended in oil it's so smooth and light. And then there's the smell. Nothing has the scent of a tube transceiver when she's hot! When I was a kid, a local ham had Heathkits wall-to-wall and the smell of warming glass, bakelite and dust is unmistakable.
I've read plenty of reviews of this and other rigs from this era where the reviewer regrets having sold it - I think this one is a keeper.
The Amplifier
February 2013: I've spent the last two months on-and-off working on a linear. I got fed up with only having 100W on HF - and besides, my licence allows 400W, which is 6dB or one full S-point difference. That doesn't amount to much on a clear band, but at the noise threshold or in the presence of QRM, 6dB is significant.
So I asked around locally if anyone had the main parts - I managed to get a TB3-750 triode, a few doorknobs and a 1500-0-1500V transformer that's built like a tank. Sundries like vacuum relays and a Pi-L coil came from a local collector, as did a filament transformer (this tube needs 5V at 14A, which is a little unusual). That left me with the air variable capacitors for the output network. Importing those would be in the €100 region for each, so I decided to build my own.
You can get nice little capacitor design utilities on the web. I calculated the required plate size and quantity, got some aluminium plate and started cutting and filing - this is not for anyone who isn't patient - and a few weeks later I had working caps.
As for the design, the basic triode-based linear amp is pretty standard, but I got design details from Frits, PAØFRI here; he does a great job of a generic triode amplifier that supports a variety of different tubes. While I didn't copy his circuit exactly, his schematic is pretty accurate (below).
Another site that was really useful was Bob, WB0NNI, whose website is here. There's plenty of background reading available on the web, and if you're in Europe or the US, plenty of resources and surplus dealers where you can get used or NOS (New-Old-Stock) tubes and other tricky components.
Anyway, the main thing is, the amp's up and running, delivering around 400W PEP on 20m with some ease. Getting the output network right is proving difficult, ensuring that each capacitor has enough swing to get the required peak. I reckon they have too much base capacitance (when fully open), and combined with extra neutralization in the anode circuit, there seems to be too much inductance floating around too - bottom line is that tuning up higher than 15m is not happening. So for the moment this baby is going to be in service for 20m to 80m.
If you're interested in a linear, I'd highly recommend building one - just keep that spare hand in your pocket if you're doing a tube design because of the high voltages. You may well end up paying more than for a used oldie like the FL2100Z, but the experience is what counts. Alternatively, you may want to go semiconductor, which is a totally different design philosophy. You'll be doing plenty of circuit and PCB design, whereas for a tube design there's more hardware and metalwork required.
Has it performed for me? Inevitably the evidence is anecdotal, but so far so good - I've had some great signal reports in the last few days, which is encouraging. Perhaps a few A/B tests and getting the feel of using it will prove its value.
The Full Shebang
May 2013: Finally, the chance has come to get a classic onto the shelf in the shack. I took up an offer on the wall-to-wall suite of the Kenwood TS-830S. If you don't know this beauty, she's one of the last hybrids (semiconductor rig with tube driver and finals) from the 1980's, a similar vintage to the FT-101ZD. The picture shows the basic transceiver, the external speaker and the external VFO (VFO-230), but I also got the original microphone, the antenna tuner (AT-230) and the station monitor (SM-220) - the full package. And not only that - it turned out to be the Gold Label version with all the filters still in situ.
Now this lady is 35 years old, and I'm still getting to know her creaks and crackles, but physically she's in very good cosmetic condition inside and out. There seem to be a few functional problems that I need to sort out, like an intermittent receiver, so a full service is what's needed here - this is going to be a pleasure!
Well, so far so good - the receiver intermittency seems to have been because the connectors to the RF board needed reflowing with a soldering iron. The input connector appears to have been dry-jointed, to the extent that removal of the female from the connector assembly caused the entire male section to come out of the printed circuit board, leaving neat little holes in the solder mounds on the underside of the pcb. So that problem seems to be fixed. It was a bit of a mission to remove the RF board from the rig, but you can get great instructions from Ken, K4EAA. He does a complete refurbishment service for US-based Kenwood hybrid owners, and also provides hard-to-get Kenwood parts. He also gives an excellent guide to getting the RF board out and replacing broken mechanical couplers. You can also get loads of info from Kenwood Hybrid Restoration.
The bandswitch is quite a sensitive area in these old rigs. Since they're pcb-based they're as open to the elements as any other part of the rig, so a good clean and lubrication is a good idea. It's also worthwhile looking into the bandswitch area, with a magnifying glass if necessary, to understand exactly how it moves, and how to get the correct wafer alignment when reassembling it. I didn't do this right the first time and ended up having to jockey the knob to get the right contacts to align. A quick resetting of the outer shaft and the coupler in the PA area fixed this nicely and gave the bandswitch the crisp firmness that it should have.
Last modified: 2013-11-16 18:34:29, 15428 bytes cached
