signal generator - Printable Version
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signal generator - fields 100 - 01-07-2014
I am looking for the vintage tube type RF generator and was wondering if the old EICO (models 324 or 315) generators are decent enough for the job of aligning.Are any other affordable but reliable makes available I should look for? Thanks.
RE: signal generator - klondike98 - 01-07-2014
I have an EICO 324 that seems to do just fine. No experience with any others though. I do use the frequency counter function on my digital meter to get the right frequency though, rather than rely solely on the dial setting.
RE: signal generator - hsusmann - 01-07-2014
For radio work I have been using a modern HP3325A Synthesizer/Function Generator.
You can get them on eBay for anywhere from $75 to $150.
The frequency is of course dead on. They can be AM modulated by another audio type signal generator.
I have gotten good at repairing HP3325A and the newer HP3325B's also.
So you can sometimes get them even cheaper if you are willing to take a risk and try to repair a "Bad one".
They go up to 20 MHz on the front panel but will go to 60 MHz
in a limited fashion via the rear panel.
Just an idea...
Herb S.
RE: signal generator - klondike98 - 01-07-2014
Yes, you need both the RF signal and need to be able to modulate it with an audio signal. The EICO has an internal modulation switch or you can do external mod as Herb has done but then you'll need a separate audio generator.
RE: signal generator - TA Forbes - 01-07-2014
When using older sig gens I believe that you should also have a frequency counter to verify Hz out. This is especially important when doing alignments.
You would be surprised t see just how much off the dial on a sig gen can be.
RE: signal generator - jontz - 01-07-2014
Also, don't forget that when using and older tube type signal generator you need to turn it on and let it warm up/stabilize for 15 minutes or so. The frequency drift can be quite pronounced during warm up.
RE: signal generator - morzh - 01-07-2014
I always use mine with Freq. cntr, but to me any generator as long as it generates needed frequencies and modulartes them is good enough.
Of course buying a modern one where the display is digital makes it that much easier.
RE: signal generator - fields 100 - 01-07-2014
There is one clean Eico 315 available. Do they have internal modulation?
RE: signal generator - morzh - 01-07-2014
I think it does because it has both audio and RF, and thet the switch says Audio/RF/Mod.
RE: signal generator - klondike98 - 01-07-2014
Keep in mind that the older generators may need a recap just like old radios
RE: signal generator - fields 100 - 01-07-2014
That is the whole idea of fun-restore generator to restore the radio, lol.
On the serious note though,do I have to recalibrate the generator after recapping, or just use it with a frequency counter?
RE: signal generator - morzh - 01-07-2014
Well, I have just bought an HP200-AB, they are fairly cheap, and it will obviously need some fixin' before I could use it.
Still fun restoring an authentic HP and then playing it through the output of some old radio.
RE: signal generator - jontz - 01-07-2014
No need for a recalibration after a recap, especially if you plan on using a frequency counter. Unless you are just really anal
RE: signal generator - morzh - 01-07-2014
Recap usually does not trigger recalibration if only because those caps you change are not those affecting the oscillation frequency at all.
Sort of like when you recap your radio the caps that are affecting the frequencies, the mica and pods, stay put.
The age does trigger recalibration as parts develop deviation, which is within specs, but will affect the frequencies.
However, if it is a round dial thing and is not a digital display thing, the dial is for reference only and can never be treated as a precise setting tool, so again the recal is not necessary. A digital synthesizer-type generator on the other hand should be calibrated as typically the set figure on the display is treated as a precise reference.
RE: signal generator - fields 100 - 01-07-2014
Thanks guys for your time,I've learned a lot today.