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HeathKit sb220
- Thread starter four6zero
- Start date
People have their preferences, and they're entitled. Whether based on fact, or.... whatever. The "SSB" delay on a "hot-foot" adapter is just the same as the SSB delay in a solid-state mobile linear. Makes the relay "pause" between when your voice stops, and when the relay drops back to 'receive' mode.
My take on amplifiers of ANY kind using an internal (RF-sensing) keying circuit boils down to two shortcomings:
1: Delay on key-up. If you are loud enough at the other end to be heard barefoot, this won't affect the way you sound, much. But if they CAN hear you barefoot, why is the amplifier running? If you AREN'T loud enough to be heard until the amplifier is running, the first syllable of the word you're saying when the amplifier keys will get chopped off. It takes a fraction of a second for a RF-sense keying circuit to respond. Another fraction for the relay to close. How many times have you heard someone on SSB that has that first syllable "clipped off" before the linear keys? This puts a choppy sound on your speech, every time you pause long enough for the linear to drop out, and it has to re-key the next word you speak into the mike.
2: Having to wait until the linear drops before you can hear anybody in your receiver. If you miss the first word the other folks say after you unkey, you may not care. Or you might. Kinda gets on my nerves.
Internal "carrier key", "RF-sense", or "Hotfoot" keying is quite effective on AM, so long as the whole system is working right, and the relay doesn't chatter. The amplifier keys as soon as you do, and gives you back your receiver as soon as you unkey the mike. So long as you place the hotfoot's sensing box in line RIGHT AFTER the radio, you won't reduce the life of the big box's relays all that much. Placing it downstream from the driver will be harder on the big box's relay, since full drive wattage will now arc across the standby side of the big box's input relay when you key the radio.
The main reason we developed our 'internal' linear relay board was for customers who kept scorching the input relay in their big boxes. Using the same RF-sensing setup INSIDE a box with six 3-500Z tubes just is not as safe and effective as it is when used in a small amplifier that uses ONLY barefoot radio drive. Installing it INSIDE a large (HIGH-drive) amplifier pretty well guarantees that the input relay will arc every time you key. When these folks discovered that putting the "keying" jack on the back of the radio was cheaper than putting a new input relay in the 'big' box once (or twice) a year, it caught on. It wasn't developed to promote on a web page, but to answer the requests of our repair customers. For years, this trick was installed by just "flying" the parts across the pins on a relay, soldering them down to the relay's pins and strapping the relay down. The printed-circuit board we use now was just a means to cut the labor building them. That's why we have a relay with TWO separate outputs. Kept getting asked to strap a second relay onto the first, so a 'small' ham box could be used to key the big one, just from the radio's mike. Strapping on a second relay got old, so starting with version two, we have been using a two-pole relay. Nothing says you have to wire up two jacks on the rear of the radio if you only need one.
Making the radio system work more smoothly on SSB wasn't really the reason we developed it. It does exactly that, making a "ham" amplifier work the way it was meant to work with "ham" radios that legally have that jack on the rear. No more "clackity" every time you pause to take a breath.
I suppose IF our relay module was a big money-maker, I'd have to pretend that it's the best thing since sliced bread, and bad-mouth every other way of keying a ham box. No such luck. It's just one way of doing this. It fits my personal preferences better than the other methods.
If it didn't appeal to enough of our repair clients, we never would have made more of them after the first prototype batch.
Gotta remember one rule about technology. There is ALWAYS MORE than one way to achieve any ONE objective.
Probably ought to make another batch of them before talking it up much more than this.
73
My take on amplifiers of ANY kind using an internal (RF-sensing) keying circuit boils down to two shortcomings:
1: Delay on key-up. If you are loud enough at the other end to be heard barefoot, this won't affect the way you sound, much. But if they CAN hear you barefoot, why is the amplifier running? If you AREN'T loud enough to be heard until the amplifier is running, the first syllable of the word you're saying when the amplifier keys will get chopped off. It takes a fraction of a second for a RF-sense keying circuit to respond. Another fraction for the relay to close. How many times have you heard someone on SSB that has that first syllable "clipped off" before the linear keys? This puts a choppy sound on your speech, every time you pause long enough for the linear to drop out, and it has to re-key the next word you speak into the mike.
2: Having to wait until the linear drops before you can hear anybody in your receiver. If you miss the first word the other folks say after you unkey, you may not care. Or you might. Kinda gets on my nerves.
Internal "carrier key", "RF-sense", or "Hotfoot" keying is quite effective on AM, so long as the whole system is working right, and the relay doesn't chatter. The amplifier keys as soon as you do, and gives you back your receiver as soon as you unkey the mike. So long as you place the hotfoot's sensing box in line RIGHT AFTER the radio, you won't reduce the life of the big box's relays all that much. Placing it downstream from the driver will be harder on the big box's relay, since full drive wattage will now arc across the standby side of the big box's input relay when you key the radio.
The main reason we developed our 'internal' linear relay board was for customers who kept scorching the input relay in their big boxes. Using the same RF-sensing setup INSIDE a box with six 3-500Z tubes just is not as safe and effective as it is when used in a small amplifier that uses ONLY barefoot radio drive. Installing it INSIDE a large (HIGH-drive) amplifier pretty well guarantees that the input relay will arc every time you key. When these folks discovered that putting the "keying" jack on the back of the radio was cheaper than putting a new input relay in the 'big' box once (or twice) a year, it caught on. It wasn't developed to promote on a web page, but to answer the requests of our repair customers. For years, this trick was installed by just "flying" the parts across the pins on a relay, soldering them down to the relay's pins and strapping the relay down. The printed-circuit board we use now was just a means to cut the labor building them. That's why we have a relay with TWO separate outputs. Kept getting asked to strap a second relay onto the first, so a 'small' ham box could be used to key the big one, just from the radio's mike. Strapping on a second relay got old, so starting with version two, we have been using a two-pole relay. Nothing says you have to wire up two jacks on the rear of the radio if you only need one.
Making the radio system work more smoothly on SSB wasn't really the reason we developed it. It does exactly that, making a "ham" amplifier work the way it was meant to work with "ham" radios that legally have that jack on the rear. No more "clackity" every time you pause to take a breath.
I suppose IF our relay module was a big money-maker, I'd have to pretend that it's the best thing since sliced bread, and bad-mouth every other way of keying a ham box. No such luck. It's just one way of doing this. It fits my personal preferences better than the other methods.
If it didn't appeal to enough of our repair clients, we never would have made more of them after the first prototype batch.
Gotta remember one rule about technology. There is ALWAYS MORE than one way to achieve any ONE objective.
Probably ought to make another batch of them before talking it up much more than this.
73
M
mmckay2302
Guest
sb-220
You know every one has to learn but your messing with the wrong amp. This isnt a toy like your mobile rigs this thing will kill you if you dont pay attention. The guy is giving you alot of good advice except one. Read the book, there is alot of info on the internet about this amp and you should read as much of it as you can before you decide to use it. Most solid state rigs dont like this amp and will fold back on its power if the SWR isnt correct. The tubes are not cheap and most people have no idea what fifteen hundred watts of tube power will do. Just do some reading about your system and the amp before you jump. GOOD LUCK
mike CDX-2302 (im back)
You know every one has to learn but your messing with the wrong amp. This isnt a toy like your mobile rigs this thing will kill you if you dont pay attention. The guy is giving you alot of good advice except one. Read the book, there is alot of info on the internet about this amp and you should read as much of it as you can before you decide to use it. Most solid state rigs dont like this amp and will fold back on its power if the SWR isnt correct. The tubes are not cheap and most people have no idea what fifteen hundred watts of tube power will do. Just do some reading about your system and the amp before you jump. GOOD LUCK
mike CDX-2302 (im back)
No doubt aboutt that... I watched a guy fool with the inside of one and got knocked to the ground like the hammer of Thor hit him...
K
kc2jgl
Guest
kc2jgl said:
Nomad Radio Key Board module
I should probably make another batch before showing it around too much.
73
very good info. do you have any of those hot rod kits left? would really like one of those pride power supply kits too...
Take care
There is a connector on the rear of the sb220 that will attact to the keying circuit of your transceiver. Your transceiver should have a keying output jack usually on the rear. The SB220 is not like a solidstate amp. It has to be externaly be keyed. The rf from your transceiver will not key it. Also you have to be careful with the SB220 because the keying circuit was not designed for solidstate rigs. If you are using a modern rig as the exciter you must modify the keying circuit as the high voltages present in the SB220's transmit relay will blow up the electronics in a modern solidstate rig. See SB220 mods at Harbach Electronics. He has some great kits to update your SB220 to work with modern solid state riggs as well as some kits to take care of inherent design flaws of the SB220 Good Luck. Harbach Electronics - Products
There is a connector on the rear of the sb220 that will attact to the keying circuit of your transceiver. Your transceiver should have a keying output jack usually on the rear. The SB220 is not like a solidstate amp. It has to be externaly be keyed. The rf from your transceiver will not key it. Also you have to be careful with the SB220 because the keying circuit was not designed for solidstate rigs. If you are using a modern rig as the exciter you must modify the keying circuit as the high voltages present in the SB220's transmit relay will blow up the electronics in a modern solidstate rig. See SB220 mods at Harbach Electronics. He has some great kits to update your SB220 to work with modern solid state riggs as well as some kits to take care of inherent design flaws of the SB220 Good Luck. Harbach Electronics - Products
I know this thread is older than dirt, but I was curious if I could T(?) into my Mini Scout keying circuit and add a RCA jack to the rear of the modulator to key amateur amps?
I've been kicking around the idea of buying an Ameritron 80B, but don't want to mod my 201A to key it and have no desire to use a foot switch.
I've been kicking around the idea of buying an Ameritron 80B, but don't want to mod my 201A to key it and have no desire to use a foot switch.
Go on you tube and search BBI sb220 doing 3000 watts .. also watch a guy named amp repair guy or a guy called tramDROK, so to keep it simple, I just get a foot switch from Heil or Radio Shack as long as it has the phono male end plug at the end, it should work. Have the sb220 already keyed before hitting the exiter. Now does it matter which plug it goes to, on the back of the sb220 it has 2 phono end plugs marked "antenna relay" & "alc". Which one?
Also, they recommend 100w drive to get full output. Does that mean 100w deak key or 100w of modulation? I am assuming they mean 100w rms.
If I key 100w and modulate to 150w rms, am I overdriving it? What can happen?
Thank you, All you fellow Radio hobbiest for all the info you've given.
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