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Foxhunter
New member
Username: Foxhunter
Post Number: 2
Registered: 4-2008
| | Posted on Saturday, May 24, 2008 - 5:37 pm: | 
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Hi this is my first post and I had a couple of questions with two items I have.
*First---I have an original Palomar 310M Bi-Linear Amp (four GE 8950 tubes). Is this a class AB amp, or what is it? Is this one "the skipper" I've read a little about in your archives?
*Second---I have a small Fatboy modulator (two SD1446 pills). Please tell me the highest proper input into that? RF Parts lists the transistor specs at 5W in 90W out---so 5W should be my deadkey? Is there ANYWHERE that I can find a schematic/instructional on it?
I am not licensed at this time but will be shortly and am going for my General Class. I'd appreciate a reply ! |
Patzerozero
Senior Member
Username: Patzerozero
Post Number: 4251
Registered: 7-2004
| | Posted on Saturday, May 24, 2008 - 8:47 pm: |
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can't help you with the tube amp, but as for the fatboy....1st, it's a CB amp, class 'C', and unless you are extremely meticulous when adjusting it, hams will know it's a cb amp right away. best bet is to not use it on the ham bands, unless you use it on AM or FM simplex on 10m. as for power input into the fatboy-if it has a variable knob on it, turn it fully clockwise, and forget it's even there. then turn radio mic gain all the way down. if radio has variable power on it, turn it to minimum, if not, remove radio cover & lower power output to a watt or so. turn amp on, key radio, and adjust radio power output til wattmeter shows amp doing about 45 watts dead key. later you may find radio is keying only 3 or 4 watts, but don't go any higher, keep amp at 45 watts out. then adjust mic gain til you see about 180 watts PEP, or 100-130 swing on a non-peak reading meter.
that's pretty much the instructions for it. 90 watt transistor x 2 = 180 watts output(PEP). divide by 4 for dead key, that's your 45 watts. switch on for amplifier, off to bypass. if it has variable.....keep heatsink/fans unobstructed & be sure amp stays relatively warm, or less. use on SSB can be done, but if you want to use an amp on SSB, you're better off with a texas star. as for schematic, forget it. if you're curious as to what it looks like, get a copy of the texas star manual. it's actually pretty close. |
2ir473
Intermediate Member
Username: 2ir473
Post Number: 143
Registered: 7-2002
| | Posted on Sunday, May 25, 2008 - 9:55 am: |
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Like Patzerozero said, most of these CB amplifiers aren't real clean enough for use on the ham bands. Beyond just clean audio on your signal, there are other factors, such as harmonics that are transmitted from the amplifier. These harmonics may be well above the frequency you are transmitting on, and may actually be interfering with some other service, and you wouldn't even realize it. Often, the CB amps don't have the necessary filtering to keep them real clean for the ham bands.
Of all the CB amps out there, I believe the Texas Star amplifiers are the cleanest ones I have heard, and all but the little modulator, are true class AB-1 biased, for the cleanest audio on SSB.
I wish there were an inexpensive CB amplifier that could be used on the ham bands, but unfortunately, quality costs $$$.
Also, if you are going to be getting a general license soon, you figure that most HF rigs are capable of producing 100 watts output on their own. In order to see or hear a difference on the receiving end, you would have to go to 400 watts. The next step would be 1600 watts, in order to have a perceptible difference.
So, I would think about selling the Palomar and the Fatboy, and buying a nice ham amp like an Ameritron 811 tube amp, an Ameritron ALS-500M, or even an RM Italy BLA-300.
Paul
2IR473
CEF-218/ham #107
CDX8412
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Foxhunter
New member
Username: Foxhunter
Post Number: 3
Registered: 4-2008
| | Posted on Sunday, May 25, 2008 - 9:21 pm: |
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Thank you both for the posts. I appreciate the response. Not to incur anyone's wrath, I'd been operating on the Citizen's Band initially and had the Fatboy modulator for that purpose. As my interest's grown I began to read and explore the Amateur Radio world and would like to "be legit" and try the HF. I will certainly remember and apply what I've read here and on the rest of the forum. Yes I wouldn't be interested in running any "dirty" equipment generating harmonics/spurious emissions and the like. As I already had the two units in question I was curious what you members had to say about their characteristics. I will read on, and I have another question I'll be posting next in regards to the use of high volume/high farad capacitors. Thank you gentleman ! |
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