I agree.
Just ran across a used two tube GI7b box for $750 asking price. Probably get it for $650 if I really needed it.
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New to CB radios, trying to find a kit to build a 8 pill linear amp.
- Thread starter Kevin Huddleston
- Start date
I agree.
Just ran across a used two tube GI7b box for $750 asking price. Probably get it for $650 if I really needed it.
Hi Kevin,
RF electronics is a finicky beast, and if you have any friends or co-workers who are actual electrical engineers who got their degrees within the last 20 years or so, they will refer to RF as black magic or voodoo.
This is because there are specific design techniques and rules that must be understood in order to design or build an RF device, and they really don't teach that stuff much these days.
for example, the actual placement of some of the parts on a linear amplifier can change it's tuning and performance. moving a broadband transformer 1/4" might have an effect on the value of capacitor being used to tune it for example.
Add to that the fact that selling any sort of kit that will allow you to build an RF amplifier that would work on CB frequencies is illegal, and therefore the building of these amps is done sort of 'underground'.
do not expect to be able to look at a parts list, and some pictures, and then copy them in order to create a working amp.
even if you did manage to get all the right parts, solder them all to a board, and connect the amp to a radio, how would you even know how well it's working?
People tend to think of CB radio as sort of entry level electronics just because of how old the tech is, and how ubiquitous the equipment seems to be,
It is anything but that. the circuits involved are very complicated, and the parts can be very expensive.
just like anything else these days, you can't build something for anywhere near the price you can buy it for from someone else.
knowing how to solder is the electrical equivalent of knowing how to pound a nail.
it doesn't mean you can build a house.
I mean no offense by these statements as many of us thought of doing just what you are wanting to do when we first entered the hobby.
The longer we are in it the more we realize how foolish of an idea it was.
The people telling you to concentrate on the antenna are giving you sage advice.
here is the real way it works when it comes to power output, radio receivers, and the human ear.
if you have a radio that puts out 10 watts, and the guy across down tells you that you are hitting him with an S-5, in order to get to an S-6 in his receiver, you will need to put out 4x the power, or 40 watts.
want to get to S-7? that's 160 watts, and so on...
this is true whether you are talking about 1 watt or 1000 watts.
the rule of 4 applies.
so, it all comes down to Db (decibel) gain from where you started to where you are trying to get to.
a 3 Db gain is equal to doubling your power output.
however, a 10 Db gain is equal to 10x the power.
the scale is not linear.
so, if you have an antenna that has no gain, like say an Antron 99, or pretty much any other vertical CB antenna, and you upgrade to a 5 element beam, you can realize about a 10x gain in power output.
a 100 watt radio running an Antron 99 would be the same as a 10 watt radio running a 5 element beam.
now here's the real kicker!
you get that same gain on receive when you upgrade the antenna!
get your dad a good antenna, up as high in the air as he can get it, and buy yourself a 2 pill or a 4 pill amp from someone you trust (we have a gear swap shop here on the forum) and he will have a SMOKIN! station.
hope this helps.
LC
RF electronics is a finicky beast, and if you have any friends or co-workers who are actual electrical engineers who got their degrees within the last 20 years or so, they will refer to RF as black magic or voodoo.
This is because there are specific design techniques and rules that must be understood in order to design or build an RF device, and they really don't teach that stuff much these days.
for example, the actual placement of some of the parts on a linear amplifier can change it's tuning and performance. moving a broadband transformer 1/4" might have an effect on the value of capacitor being used to tune it for example.
Add to that the fact that selling any sort of kit that will allow you to build an RF amplifier that would work on CB frequencies is illegal, and therefore the building of these amps is done sort of 'underground'.
do not expect to be able to look at a parts list, and some pictures, and then copy them in order to create a working amp.
even if you did manage to get all the right parts, solder them all to a board, and connect the amp to a radio, how would you even know how well it's working?
People tend to think of CB radio as sort of entry level electronics just because of how old the tech is, and how ubiquitous the equipment seems to be,
It is anything but that. the circuits involved are very complicated, and the parts can be very expensive.
just like anything else these days, you can't build something for anywhere near the price you can buy it for from someone else.
knowing how to solder is the electrical equivalent of knowing how to pound a nail.
it doesn't mean you can build a house.
I mean no offense by these statements as many of us thought of doing just what you are wanting to do when we first entered the hobby.
The longer we are in it the more we realize how foolish of an idea it was.
The people telling you to concentrate on the antenna are giving you sage advice.
here is the real way it works when it comes to power output, radio receivers, and the human ear.
if you have a radio that puts out 10 watts, and the guy across down tells you that you are hitting him with an S-5, in order to get to an S-6 in his receiver, you will need to put out 4x the power, or 40 watts.
want to get to S-7? that's 160 watts, and so on...
this is true whether you are talking about 1 watt or 1000 watts.
the rule of 4 applies.
so, it all comes down to Db (decibel) gain from where you started to where you are trying to get to.
a 3 Db gain is equal to doubling your power output.
however, a 10 Db gain is equal to 10x the power.
the scale is not linear.
so, if you have an antenna that has no gain, like say an Antron 99, or pretty much any other vertical CB antenna, and you upgrade to a 5 element beam, you can realize about a 10x gain in power output.
a 100 watt radio running an Antron 99 would be the same as a 10 watt radio running a 5 element beam.
now here's the real kicker!
you get that same gain on receive when you upgrade the antenna!
get your dad a good antenna, up as high in the air as he can get it, and buy yourself a 2 pill or a 4 pill amp from someone you trust (we have a gear swap shop here on the forum) and he will have a SMOKIN! station.
hope this helps.
LC
I hate to tell someone not to do something, as I grew up / spent many years playing with radios / amplifiers, but if you didn't grow up with radio / RF, learning, etc., and have no understanding of it at all, building an 8 pill is not a good idea. You'll likely never get all the stages nor the input / output matched right; your handy work might "look" decent, but it may not work right at all. The money spent fiddling with it you could have bought one already built. Blow up all the transistors on accident, now hundreds more into it.
And as mentioned, going from a 6 pill to 8 pill is kind of a waste of time.
I don't think I'm adding any useful info, but just browsing the forum after noticing cbtricks down again. I haven't talked on radio in quite a few years, but still occasionally browse the forums, and check cbtricks from time to time knowing it might be gone at some point.
And as mentioned, going from a 6 pill to 8 pill is kind of a waste of time.
I don't think I'm adding any useful info, but just browsing the forum after noticing cbtricks down again. I haven't talked on radio in quite a few years, but still occasionally browse the forums, and check cbtricks from time to time knowing it might be gone at some point.
Here is a straight 4 x 2sc2510 Toshiba plug in the wall box, claims up to 250w drive and 1500w PEP out.
Armadillo Base amplifier