Discussion in 'Ham Radio Discussions' started by KA4DPO, Oct 11, 2017.
European sweep-tubes were often substituted. EL/PL504 are commonly used.
Can new sweep tubes be had now a days ?
Well, maybe a poor choice of terms on my part. Sure, the designers made a lot happen with a low parts count, just like with the rig as a whole. But I just *hate* that the bandspread changes so much as you go to different bands. It's not that big a deal on 80m/40m/20m. But on 15m and especially 10m, it gets pretty hard to know just where you are. And the tuning gets touchier as you go up. I mean, they crammed the whole 10m band onto the same dial as 40m. Just like my old KnightKit, Heath, etc. VFOs. I just wish Swan had used a hetrodyne design. I can see their reasoning a little more with the compact/budget Cygnet transceivers. But I'm just surprised they didn't put a hetrodyne VFO in the "better" 350 and up models.
Sure, but it will have been manufactured year ago, sitting on a shelf until now. I believe the Russians and maybe some others made sweep tubes until very recently. They just wouldn't necessarily cross to the once common types used in ham equipment.
Using sweep tubes was actually a very smart idea in the 60's. There were millions of them and they were inexpensive compared to transmitting tubes like the 807 and 6146. I thought about doing the 6146B mod on my T4XB quite a few years ago but decided against it. I wanted to keep the radio stock and also, I have three sets of 6JB6's so I don't think I will run out. If you keep tune ups short and into a good load, and don't try to squeeze every last watt out of them, sweep tubes can last quite a long time. They are not nearly as rugged as 6146's or 807's and can easily be damaged by excess plate dissipation. That's why sweep tubes are no good for plate modulated AM. A modified form of screen grid modulation (controlled carrier) was used in some sweep tube rigs like Drake but I always avoided it because it still stressed the sweeps and caused premature failure.
I'm pretty sure the Swan rigs did not have AM but at the time they were built most hams were getting out of AM anyway. I do remember back in those days hearing, every now and then, some goober who did not have their carrier balance set correctly. It would case a weird sound on voice peaks, especially in my barn door National receiver. I wish I could find a brand new, still in the box SW-240, that would be very cool indeed.
Yep...those sweep tubes didn't like fumble fingered tuning. If you were careful, however, they could go a long time. In all the years I had my 500, I replaced the finals once. And as DPO says, they were plentiful and cheap then.
I guess the 750 was their Swan song.
I used to borrow a Swan 250C for VHF contests - it was a fun rig. Lots of friends had the 350. One lawyer friend of mine had a huge car with a 500CX stuffed under the dashboard - definitely one of the most effective mobiles I can remember.
Swans were great until they came out with the notorious Swan 1011, which changed the company name to 'Swine' for most of us. They sold the 1011 to a company called Siliconix, which mysteriously appeared at the same address as Swan. Too bad, I think they made a major error with the 1011, but I bet they sold more of those than some of their mainstream models.
They did that to keep the price down. It wasn't so much about parts count - even the 260 has a cubic S-load of parts - but about using inexpensive parts rather than expensive ones.
They are that way because of frequency multiplication. The VFO is on 40 but the frequency doubles for 20, triples for 15, quadruples for 10 - and the stability, tuning rate and bandspread go down.
Remember that the 350 was their first 80-10 transceiver (it was preceded by the single-banders (SW-120/140/175) and the triband SW-240.
IMHO, the history in interesting. By the late 1950s, SSB had been "popular" in US HF amateur radio for more than 10 years, but it had never REALLY caught on, because 1950s SSB gear was expensive, bulky, heavy, and complex to operate. There were some efforts made to popularize the idea of transceiving (one VFO for both tx and rx), but they weren't too successful (Collins KWM-1, Cosmophone 35 and 1000).
Then Collins came out with the KWM-2 and S-line, and the game changed. Even though they were very expensive (1961 prices: KWM-2 $850, 75S-1 $520, 32S-1 $666, 516F-2 power supply for KWM-2/32S-1 $115), they sold well from the start. The Drake TR-3 was $495 in 1964, plus $80 for the power supply. Hallicrafters SR-150 was $650, without power supply. The National NCX-3 was $370 without power supply, but it only did 3 bands. Heath wasn't in the game yet, except for the single-banders, but everyone knew they would be soon.
So Swan had a narrow price window. The 400 was moderately successful, but it needed an external VFO, and the package price (rig and VFO, no power supply) was over $500.
The 350, at $395 (plus $85 for the power supply) was a big hit. Under $500, 400 watts PEP (claimed), one box. It was priced far enough below the TR-4 ($585) and NCX-5 ($685) that its only competition was the Galaxy V ($399).
Swan sold a lot of 350s and 500s, so they didn't see the need to change the design too much. Keeping the price down was #1 - and that was difficult, considering that they were point-to-point hand-wired, which meant a lot of manufacturing cost.
Meanwhile. Heathkit stole the show with the SB-line - particularly the SB-101 and its less-expensive cousin, the HW-101. Manufacturing cost was very low because they were kits. The Cygnet family was Swan's attempt to compete with the HW-101, by taking the 350 design and stripping it to the bone.
73 de Jim, N2EY