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[Amps] Roller inductors

To: Carl <>, Glen Zook <>
Subject: [Amps] Roller inductors
From: Steven Katz <>
Date: Fri, 17 Oct 2014 16:35:59 +0000
List-post: <">>
True, roller inductors are often an accident in the waiting but I must admit my 
50s vintage Johnson Thunderbolt (2 * 4-400s) had one which was cranked nearly 
every day for lots of band changes and actually never acted up in any way in 
all the years I had it (several).  Only about 800W output amp, though.

The edge-wound silver-plated roller in my Henry 3K Premier never failed, 
either, until the 1994 earthquake made it fall to the floor and take a huge 
mechanical shock.  That wedged the roller between turns -- badly, and also 
broke the plate RF choke (ceramic).  I drove the RF deck down to Henry a couple 
weeks later and they replaced both components for free, while I waited and 
drank coffee.  They didn't really have to do that, but didn't seem to mind.  
The roller never acted up after that, and I had the amp until 2001.  That amp 
ran 1500W output easily and was "cranked" quite a lot.


-----Original Message-----
From: Amps [] On Behalf Of Carl
Sent: Friday, October 17, 2014 9:06 AM
To: Glen Zook
Subject: Re: [Amps] HV Diodes

At that low power level that size roller is usually adequate but the moving 
parts wear and create intermittents. They become a maintenance headache for 
some owners.

Its a cute little amp but it really needs a seperate grid meter for those 
fragile tubes.

For real power the one used in the Henry 8K is needed and even then they act up.


----- Original Message -----
From: Glen Zook
To: Carl ; Louis Parascondola
Sent: Friday, October 17, 2014 9:43 AM
Subject: Re: [Amps] HV Diodes

I have had a Henry/Tempo 2001 linear amplifier, that uses a pair of 8874 
tubes, which has a roller inductor, for almost 40-years.  No problems!

The "plate tuning" in this amplifier is actually uses the roller inductor. 
The plate tuning capacitors are fixed and the roller inductor is tuned.  Of 
course, the antenna loading is a variable capacitor.

I do not believe that there were that many 2001 amplifiers sold.  I have 
actually had another one in my hands but don't know of anyone else who has 
one of these.

The roller inductor makes tuning on the WARC bands easy even though the 
amplifier was designed before those bands were established.

Glen, K9STH


On Friday, October 17, 2014 7:58 AM, Carl <> wrote:

A roller inductor is the last thing you want in a ham amp of desktop size
Ulvin Tremendus in Spain has the dual 8877's already.


we  have been waiting on that dual 8877 amp with roller inductor for some
time now.  Many die hard hams would prefer that over solid state.

-----Original Message-----
From: Dan Simmonds <>
To: Carl <>
Cc: Amplifier Mailing List <>; Manfred Mornhinweg
Sent: Thu, Oct 16, 2014 8:38 pm
Subject: Re: [Amps] HV Diodes

Perhaps, yes. But regardless of how inexpensive the Chinese amps may be,
at the end of the day they will still be Chinese amps, metaphorically

Exciting things to come in 2015 in the QRO solid state market. Trust me
on this :)

Dan  KK3AN
> The Chinese have some serious amps but no US certification yet that Im
> aware of. Once they get going watch out! They are already taking over
> the tube business.
> Carl
> KM1H

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