Another Linear amplifier killer, the Band Switch.
HTML-код
- Опубликовано: 13 сен 2024
- Mechanical connections, especially one's that move are also notorious amplifier killers, relays, pots, and switches. Here is a big one, the Band switch. Single Band amps, made for one band only, like a 10 or 11 meter only amps, do not even have a band switch. However, most Ham band amps do. The switch connects to the proper coil tap for the perspective band on a multi band amp. Sure, a heavier switch helps, but with time, even the best switches are prone to failure. Metal fatigue makes the connection lose its grip and tarnish and grime make them lose their electrical connection. Another quick kill is if the operator moves or changes bands while keyed. No switch can handle that. Same with when an operator turns on the Preamp while keyed. Bye-Bye preamp transistor. Sure, band switches can be tightened and cleaned, that helps, but still 50-year-old metal. Better to replace and best, if possible, just bypass it and convert to a single band amp. Most know that with every connection an amplifier goes through, it loses power. Same with the bandswitch. RF power in, then through the band wafer, then out another switch, plus that big ole un-needed big Ham band coil is in the mix too. On average, removing all the un-needed stuff and monobanding a mulitband amp increases efficiency and gives you about 5% more out. This is power the tube was already putting out, but lost going through the added circuitry. More out, more dependable amp and slightly cleaner too. Win, Win.
That black tarnish is silver oxide, which is still conductive. If you put that switch in Tarn-X, it will remove 99% of the tarnish and convert it back to silver.
I have used surplus switches to replace burnt parts, and restored the amp to near new condition. Rather than limit an amp to one band and make the resale value near zero, restore it and keep it in the market!
That section of coil has a large value in the electronics community!
silver oxide is not 100% conductive. Also, since this channel is mainly for CB'ers and kinda a CB for dummies at that, no offence meant to anyone, most CB'ers rather have a more dependable amp that puts out a little bit better than an amp with all the useless Ham Bands and the amp killing Band Switch. I am writing a book on a totally different subject, but one theme in the book is to "know your audience." You don't teach Trigonometry to 3rd graders.
Your right on again Doc ! The Palomar 300 A was a bastardized ham amp, so they could sell it to cber’s ! The high low switch . High is for the driver tubes low is for just the finals so you could hit it with a ham transceiver. It’s impossible to tune on the ham bands. See BBI ‘s video on tuning this amp! Bottom line it’s a CB amp! JohnBoyUtah KJ7TBR 🇺🇸😎🎙📡
Its a gimmick. the amp was never really meant to work on 20 40 80. there is no input coils for those bands. It was only there to pass FCC rules. Like pedals on electric scooters. the pedals are useless but it passes the loophole of needing pedals.
I agree. Mono band and get the non used stuff out is the best way to go on those amps. A couple of Nomad boards is always a nice addition too. Nice video!
Nomad makes great stuff, but its not cheap. You pay for what you get.
Getting rid of the band switch is a way to reduce frequency drift in the 1011 radios. Years ago I had the mode switch on a Tram Titan 2 catch fire! Apparently the insulating material became conductive and that was it.
Unfortunately, this happens too often.
That coil looks exactly like the coil Ham Stick Antennas made for there 40M Antenna ...
Very informative
Glad you liked it
Personally, I wouldn't have removed the band switch and tank coil, unless it was absolutely necessary!
Different strokes for different folks.
Good information! Any good tips/articles or videos on mono banding a sb 220? Or are they built heavy enough stock? Thanks doc
I think the SB-220 is not a well built amp. There are hundreds of articles on addressing most of its problems. To me, the main issues are, undersized transformer, undersized tune cap, load cap, and band switch, voltage doubler for the HV, no step start or surge limiting, cheezy bias circuit, not enough cooling for the tube pins, and no meter protection come to mind.
@@tramdr ok thanks I got one from a local and I grounded the grids, I drive it at right about as much as the transformer will take and I’m pretty sure the fan is upgraded. Thanks for the information. If I get serious I’ll get a real 500 a amp lol
Looks like the one I need is a pal c-2
or a Siltronix 6 which is kinda hard to find and I don't have.
A switch like that burn up a mint browning mk3 I had.
A very common problem with amps and with the Mark 3 radios.
Hey tram doctor I am looking for a vfo TRC48 please let me know if you happen to have one I could purchase
Nope, don't have either the Siltronix or PAL for that. I do have a good Glen VFO that will work, but that will not be cheap.
I have a pride dx300 without the band switch it will not load up it has the original 10 m coil..... no matter how I hook it up to the load capacitor .....what should I try next
ruclips.net/video/b36wJbbo3J4/видео.html
Hello...I have a Varmint XL 450. I have some questions for you. If you could message me. Thanks!!!
Tramdr at Yahoo.com
Seems like I read that Pride amps were built by disabled people?
I remember when Heathkit came out with the 220 amp that had 10 meters removed. Hammy Hams were saying that CBers could no longer use them on 11 meters!🤣 Those hams sure were good for some laughs!
Yes Pride was "Made with Pride by the handicapped" First they removed the 10 meter band from the Bandswitch on a SB-220 then when that didn't work, they came out with the SB-221 which not only didn't have 10 meters, they added a device on the input side that was labeled 'Filter'. It was a filter all right, an 11 meter no pass filter. It blocked 11 from coming in. I knew a guy that had one, drove his 221 with a Phantom 500. 500 watts in to get a thousand out. He did this for 10 years and the amp was right up close to him on his desk. At about 55 he caught brain cancer. I still think this was why.
@@tramdr Wow, that’s a crazy way of running the Heathkit amp! I’m also inclined to think his cancer might have been caused by that.
I knew a fellow who built Heathkit amps from kits to sell to the “Big guns” in the East St. Louis Illinois area. Back in the 70’s there was a channel that the huge amps hung out on. He used to drill the rivets out of that filter and remove it from the kit. He ordered the coil from Heathkit that they left out of the new kits and install it in the 15 meter position. Anyway this guy built those amps from kits and added a second power supply, because they were weak. Then he started adding another tube. Then two more tubes and three power supplies. It was crazy! But the point is that there were Hams who actually thought the FCC restrictions would stop their use on 11 meters. He used to laugh at their stupidity.