However pulse rated tubes are often the most sought after for ham amps and
are even used by the manufacturers.
Examples are the 4PR1000A, 3CPX800A7, 3CPX1500A7, YC-156, and on and on.
They must provide extreme levels of linearity in medical service and are
conservatively operated. In amateur service they are known for ruggedness
and superb linearity.
Bandwidth has nothing to do with it.
Carl
KM1H
----- Original Message -----
From: "Bill Fuqua" <wlfuqu00@uky.edu>
To: "jeremy-ca" <km1h@jeremy.mv.com>; "Roger (K8RI)"
<sub1@rogerhalstead.com>
Cc: "Amps" <amps@contesting.com>
Sent: Monday, March 24, 2008 11:59 AM
Subject: Re: [Amps] What is this amp set up for
>I have gotten several 200 MHz power pulsed amplifiers from University
>surplus sales.
> These were used in MRI systems. One interesting one had a version of the
> 8877 with out
> fins clamped in a 1/4 wave cavity. It had a solid state driver amplifier
> that was also pulse rated.
> I think a hint may be the spec. of 200 MHz plus or minus a few MHz and a
> 2kW pulse rating for
> power. Pulse operation is usually not used in amateur work due to the
> wide band width.
>
> 73
> Bill wa4lav
>
>
> At 08:52 AM 3/23/2008 -0400, jeremy-ca wrote:
>>With 2M amps being not that uncommon the price is usually lower.
>>
>>With the only 222 amps being custom made or modified as that one they tend
>>to be more in demand. And you know what happens on Ebay when the frenzy
>>starts.
>>
>>Those holes look to be for extra air flow thru the cover after it got hot
>>and deformed. I'd open it all the way and install a silicon rubber chimney
>>with a non restrictive mesh on top. I had to do that with my 144 and 222
>>amps; made a huge difference and no more tuning drift.
>>
>>Prices are even higher for a good 432 amp in the 8938 and 2x 3CX800
>>category.
>>I gave up finding a 8938 at a good price and wound up rebuilding a Collins
>>USAF 350 MHz cavity amp with a GE 2500W dissipation monster tetrode. It
>>was
>>designed for a KW out as an AM linear.
>>
>>Carl
>>KM1H
>>
>>
>>
>>
>>
>>----- Original Message -----
>>From: "Roger (K8RI)" <sub1@rogerhalstead.com>
>>To: "jeremy-ca" <km1h@jeremy.mv.com>
>>Cc: "Amps" <amps@contesting.com>
>>Sent: Sunday, March 23, 2008 2:18 AM
>>Subject: Re: [Amps] What is this amp set up for
>>
>>
>> > jeremy-ca wrote:
>> >> When I first saw that listing it said modified; I see he has revised
>> >> it.
>> >>
>> >> Thats not a bad price for smoke on 222 if the tube is perfect and
>> >> trimming back the strip line should be rather easy
>> > I would think it's too high even with a new tube. Really nice ones
>> > unmodified on 2, or 6-meters have been going for around $1400 (give or
>> > take) Look carefully at the top. It is bent in and has a circular row
>> > of
>> > what appear to be holes. I have one on 2 that is *almost* mint. It
>> > looked crappy when I purchased it at a swap. I figured I could use it
>> > for
>> > parts and hoped for a reasonably good tube. A little cleaner and it
>> > looks
>> > almost new with a good tube.
>> >
>> > 73
>> >
>> > Roger (K8RI)
>> >>
>> >> My own amp for 222 is a 8877 and I scaled down a 2M version and then
>> >> used
>> >> a VNA for final trimming. I built it in a partially built Henry 44-46
>> >> MHz
>> >> box I picked up in a swap.
>> >>
>> >> Carl
>> >> KM1H
>> >>
>> >>
>> >> Carl
>> >> KM1H
>> >> ----- Original Message ----- From: "Roger (K8RI)"
>> >> <sub1@rogerhalstead.com>
>> >> To: "jeremy-ca" <km1h@jeremy.mv.com>
>> >> Cc: "Amps" <amps@contesting.com>
>> >> Sent: Saturday, March 22, 2008 9:19 PM
>> >> Subject: Re: [Amps] What is this amp set up for
>> >>
>> >>
>> >>> jeremy-ca wrote:
>> >>>> Hmmm, his description says it is modified for 220.
>> >>>
>> >>> Isn't that "modifiable" to 220?
>> >>> Although advertised as a 2-meter amp, "I'd guess" it's one of those
>> >>> that
>> >>> was used for plasma or industrial heating at 200 MHz that can be
>> >>> modified for 220. Some outfit has had a similar one in very nice
>> >>> shape
>> >>> (with new tube)on there since last Fall with no takers. Their BIN
>> >>> price
>> >>> has finally started down. Unless they find some one who really wants
>> >>> (and can use) one for 220 both are basically parts amps.
>> >>>
>> >>> I purchased one all set up for the 2-meter band in good shape that
>> >>> only
>> >>> required a good cleaning for less than he's asking for one that may
>> >>> require a lot of work. I was learning about building filters for it
>> >>> on
>> >>> here last summer.
>> >>>
>> >>> 73
>> >>>
>> >>> Roger (K8RI)
>> >>>> Carl
>> >>>> KM1H
>> >>>>
>> >>>>
>> >>>> ----- Original Message ----- From: "Roger (K8RI)"
>> >>>> <sub1@rogerhalstead.com>
>> >>>> To: "Amps" <amps@contesting.com>
>> >>>> Sent: Saturday, March 22, 2008 7:59 PM
>> >>>> Subject: [Amps] What is this amp set up for
>> >>>>
>> >>>>
>> >>>>> the amp listed on
>> >>>>>
>> http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=350038955687&ssPageName=ADME:X:AAQ:US:1123
>> >>>>> is listed as a 2-meter amp but the specs list it as 200 MHz +/-10
>> >>>>> Mhz.
>> >>>>> Also the output filter is far smaller than the one in my 2002A
>> >>>>> which
>> >>>>> is
>> >>>>> set up for 2-meters.
>> >>>>>
>> >>>>> 73
>> >>>>>
>> >>>>> Roger (K8RI)
>> >>>>> _______________________________________________
>> >>>>> Amps mailing list
>> >>>>> Amps@contesting.com
>> >>>>> http://lists.contesting.com/mailman/listinfo/amps
>> >>>>>
>> >>>>
>> >>>>
>> >>>
>> >>>
>> >>
>> >>
>> >
>> >
>>
>>_______________________________________________
>>Amps mailing list
>>Amps@contesting.com
>>http://lists.contesting.com/mailman/listinfo/amps
>
>
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