[Amps] Bandswitch source or roller inductor

[R.Measures]

On Oct 13, 2004, at 10:29 AM, craxd wrote:

> Manuel,
>
> I seen some on Ebay for sale the other day. They had several different 
> band switches and also several roller inductors. To by a new roller 
> inductor, you might want to try Oren Elliott as I'd say their pricing 
> would be much less than anything from Henry. The only frequencies you 
> might run into problems with a roller inductors would be 50 MHz (6 
> meters). Roller Inductors have been used in homebrew and a few factory 
> amps for years. The main thing, say for 15-10 meters, you need to make 
> sure the coil will carry the current. If it's not large enough, the Q 
> will be affected greatly. Here though, you could have a large DPDT 
> relay to throw in a 10 meter coil, and use the roller inductor for 
> lower frequencies.

No relay or switch is needed for the added 10m section since, for 10m 
operation, the roller L is set to zero so the only inductance in the 
tank is the stray L in the roller L and the 600 or so nH in the 10m 
section.
>
> Oren Elliott:  http://www.orenelliottproducts.com/index.html
>
> Will Matney
>
>
> Manuel R. Alonso wrote:
>
>> Hello,
>>
>>
>> Does anybody know of a good source for reasonably priced 
>> bandswitches? I called Multi-Tech industries and a decent switch 
>> costs $250.00. The nice one's at surplus sales of nebraska are also 
>> up there in price.
>> How about uning the Henry Roller inductors in lieu of bandswitch / 
>> tapped coil. The Henry rollers are less than $200.00 ea and that is a 
>> complete assembly.
>> Does the roller present a problem at the lhigher bands were very low  
>> inductance is needed in the Pi circuit?
>> The amp will have two 4CX800 russian tubes. tube RL = 975.
>>
>> Thanks
>>
>> Manuel R. Alonso
>>
>> KC4MNE
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>
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Richard L. Measures, AG6K, 805.386.3734.  www.somis.org