I was looking at my relay collection and had a question??

[ElectronTubesRule]

I have an assortment of used and new Bosh, P&B, Siemens, Grundig etc....they are all 12-24V DC rated.

So I got to thinking I know scarry right? I do not have anything in the rest of this rig that is 12 or 24 volt DC everything in here that needs a voltage to trigger it is AC. So I was wondering if you guys normally just run with 115-120V relays so as not to need another rectified power source. My heater can use DC or AC I was going to run ac to it. If I run DC well that would take care of the relay and the heater.

Does one typically get a cleaner signal with DC to the heater instead of AC?

Also has anyone used a lot of solid state relays? If so what did you think compared to either open frame relays and vacuum sealed relays? In automotive CPU's I have had a lot of failures with solid state relays but at the time VW and Porsche where really putting it to their suppliers for cost savings. So I do not want to judge all solid state relays based on that one small sample size with just one company really!

From a mechanical standpoint it sure seems like they would or should be more reliable and not have the bounce associated with mechanical movement points type relays?

If you do like solid state relays what brands do you recommend. I know their is always a few companies at the top a few in the middle and a lot at the bottom of the quality control game. I would rather avoid the guys at the bottom but do not need to shop at the top either.

Also I was wondering if I buy used vacuum variables or used air variables is their someone on here that could high pot test them if I paid the shipping both ways? If not is their anyone in Michigan I could take them too to let them check them out. I would prefer not to get them into the circuit and then after putting power through the thing find out they are bad!!! Their are no shop's in my area that I would trust really to do a good job. I am sure their has to be some place in Michigan though that cater's to this type of market???

 

[Captain Kilowatt]

For the tube filaments you can use AC or DC. If the tube has an indirectly heated cathode it makes no difference at all and if the tube has a directly heated cathode DC can be slightly better as it removes any possibility of a 60Hz hum being induced into the RF waveform. Usually this is not a problem.

If you had a lot of relays to worry about it may be an issue but you will have what? One? Maybe two? Throw in a small transformer to develop control voltage for any relays you may have. I would not use solidstate relays, mechanical relays are fine. SS relays have a certain amount of leakage current even when in the off state.That may be a problem if you are dealing with HV. I prefer relays I can see the contacts and clean them if they get dirty. YMMV

I wouldn't bother with vac variables unless the power was a couple kilowatts. "Bread slicer" type open air variables are fine if the plate spacing is adequate and there are no sharp edges. Inspect the rotor and if the plates need alignment you can move the entire rotor shaft to centre the rotor plates with the stator plates. The loading capacitor need not be high voltage as discussed an another thread.

 

[ElectronTubesRule]

Thanks that was the direction I was leaning too. I will toss a 12.5 or 24 volt switching power supply in the power supply area. I was going to put everything in one box but I figured a two box setup would be easier to control heat. So power supply in one box RF deck in the other. Less parts density, more air flow and I can use cooling fans specific to what amount of cooling I need in a given area.

Things are going well. I am refurbishing a 6/10 meter sweep tube amp and I almost have all the parts for my rectifier circuit.

I got a killer deal on Dahl precision wire wound resistors that where Jan military surplus new still in the sealed box's. Only bad thing is that until I finish the ARRL prep class and get my ticket punched I can not do more then fire up the one amp and run it into a dummy load. That is like restoring a old Dino Ferrari and not having a drivers license....LOL