[AMPS] More amplifier experiments

Tom Rauch w8ji.tom@MCIONE.com
Fri, 29 May 1998 12:40:36 +0000

> Date:          Fri, 29 May 1998 10:26:13 -0400 (EDT)
> From:          km1h@juno.com
> Subject:       Re: [AMPS] More amplifier experiments

> >About 60 nanohenries at a test frequency of 100 MHz. 
> That does seem a bit high but what effect would it have in a suppressor ?
>  I have never been clear on that point since it appears that a minute
> amount of inductance is compensated for by the L that is selected.
> What test equipment was used?  HP model #  ?  I can probably get some
> network analyzer time over the weekend.

I ordered samples today from Mouser, and they did confirm they 
almost always change the prefix when the vendor is changed. They 
also confirmed they do not have any spec on the inductance of 
resistors they sell.

I have an old  HP4191A made in the late 80's, it does direct 
impedance measurements from 1 to 1000 MHz.

> >What is the test frequency and inductance measuring capability of 
> >your equipment? Does the "Tek 130" measure and display 
> >both resistance and reactance? 
> No just L at a 1KHz test frequency which I agree is rather old
> fashioned....but my nice HP digital LCR meter is kaput until I can find a
> repair facility...or the time to dig into it myself.

That might be the problem Carl. The reactance of 60 nH at 1 kHz is 
376 micro ohms. I doubt your instrument can resolve 376 micro ohms of 
inductive reactance in series with 50 or 100 ohms.

> How about MFJ sources? They already use a non-inductive resistor in their
> tuners, does their source produce a 5 or 10W version? 

Big $$$ Over two dollars each. Lead time is long, and you have to 
buy a lot of em. The 50 or 100 watters are only $5 or so wholesale.

The Allen Bradley resistors  are less than $.50 each but have a long 
lead time.

> I havent looked very close but what are Alpha, Command and QRO using?

Dunno. Denny Had used inductive carbon film types, but I never 
looked at the other guys. I have some amps, maybe I'll tear one open 
and look.

73, Tom W8JI

FAQ on WWW:               http://www.contesting.com/ampfaq.html
Submissions:              amps@contesting.com
Administrative requests:  amps-REQUEST@contesting.com
Problems:                 owner-amps@contesting.com
Search:                   http://www.contesting.com/km9p/search.htm