I have no idea if there's supposed to be a specific value of resistor - but 50
ohm carbons was what I had at the time (I bought a boxfull at a hamfest
fleamarket!) and they looked a bit weedy - so the (non-scientific)
suck-it-and-see approach was to put "a resistance" in there. I did think of
three sets of three in parallel connected in series but it just seemed clumsy
and I thought I'd try it with the one set. It worked so I left it alone.
Is there anything special about 50 ohms?
Dave G0OIL (The fellow from G land....)
--- On Fri, 16/7/10, Jim Thomson <jim.thom@telus.net> wrote:
From: Jim Thomson <jim.thom@telus.net>
Subject: [Amps] 2 x 4-1000 supressor.
To: amps@contesting.com
Date: Friday, 16 July, 2010, 1:46
Date: Thu, 15 Jul 2010 17:45:32 -0500
> From: Rob Atkinson <ranchorobbo@gmail.com>
> Subject: Re: [Amps] parasitic suppressor voodoo
> On Thu, Jul 15, 2010 at 3:00 PM, Carl <km1h@jeremy.mv.com> wrote:
>> Agree with Dave. In the past I turned out many 1-2 holers grid or cathode
>> driven to order; most covered 160 or 80-10M. Then I used 20-25W Globars or
>> surplus 68 Ohm 50W Carborundums which I bought almost 100 in sealed packages
>> for real cheap.
## whoa. The fellow from G land is using THREE 50 ohm resistor's in parallel
= 16.67 ohms.
KM1H is using a 68 ohm -50 w globar. Carl, are did u use a SINGLE 68 ohm
resistor ??
## On my single and 2 x hole 4-1000's from the 70's.. each suppressor
consisted
of 5 x 250 ohm resistor's in parallel [ 2 watt carbons]
## If I remember correctly, any combo that totaled aprx 50 ohms worked good.
## Later on, I tried using a SINGLE 20-25 watt, 50 ohm globar, and that
worked good too.
## whether 2 watt resistor's or globars used, in all cases, cu strap was used
, [ 2- 2.5 turns]
## They were all 80-10m amps... no 160m. Back then, we were still only
allowed 25 w on 160m, and
loran stations were super loud. Forget when the loran was shut down. While
the loran was still on,
160m was just a mess of 30-40 over S-9 crud.
>> Stopped that when all the local AM stations used the tubes until they were
>> even almost dead as modulators or went SS. I did about 10 3CX3000A7's and a
>> few 4CX5000A's after that.
### watch out. Some folks on here will read you the riot act.. abt 'ethics' ,
the 1.5 kw
limit, and other nonsense.
later.... Jim VE7RF.
>>
>> Carl
>> KM1H
>>
>>
>> On a 2 times 4-1000A amp (5.5kv, grounded grid, cathode driven) I used two
>> separate parasitic suppressors, each with 3 paralleled 50 ohm carbon
>> resistors inside a 15mm diamater two-turn coil of 2mm copper wire over about
>> 10mm length. The amp has worked flawlessly (80 thru 10m) for many years.
>>
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