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Re: [Amps] wanted suitable blower for 8877 tube

To: "David G4FTC" <>, <>
Subject: Re: [Amps] wanted suitable blower for 8877 tube
From: "jeremy-ca" <>
Date: Sun, 19 Aug 2007 10:04:08 -0400
List-post: <>
Looking thru the EBM site I find no listings for the R2E series below 133. 
Are the ones you mentioned discontinued?


----- Original Message ----- 
From: "David G4FTC" <>
To: <>
Sent: Sunday, August 19, 2007 2:08 AM
Subject: Re: [Amps] wanted suitable blower for 8877 tube

>>From: "Tom Rauch" <>
>>Reply-To: Tom Rauch <>
>>To: "Mike, K6BR" <>,"'Fern Rivard'"
>><>, <>
>>Subject: Re: [Amps] wanted  suitable blower for 8877 tube
>>Date: Sat, 18 Aug 2007 22:20:47 -0400
>> > How about using the Fan from the Ameritron AL-1500, I
>> > think you can buy it
>> > online from Ameritron, It works well and is pretty quiet
>> > if you drop a
>> > resister in line and slow it down a bit.  I think the part
>> > is
>> > Number is 410-3737.
>>That blower is already at the minimum possible size with
>>full line voltage for ICAS duty at 1500w output CW or SSB.
>>If you add a resistor to "slow it down", you will not make
>>safe airflow under almost any duty cycle.
>>For heavy duty cycle applications Ameritron recommends the
>>larger capacitor run blower, but no one ever likes it. The
>>extra 20dB noise stops people from using it.
>>When initially released the larger blower was used but about
>>2/3 of the amps were returned  because of noise, so the
>>slower G2E085 was substituted.
> Following on from my earlier posting, I've just realised the OP is in
> Canada, and for 60Hz operation the correct EBM blowers should be prefixed
> with an R,  i.e. R2E 085-AA 01-05, R2E 120-AR 77-05 etc., instead of the G
> which is for 50Hz operation.
> Also according to the EBM datasheet the G/R2E085 would seem a little
> undersized for high duty cycle (CCS) operation - the EBM datasheet gives
> 25CFM at about 0.32" WG whereas the Eimac datsheet states a required 
> airflow
> of 38CFM at 0.6" WG (at sea level). The R2E 108-AA 01-05 datasheet quotes
> about 40CFM at 0.6" WG which nicely fits the Eimac recommended figures.
> Having said that the G2E085 or rather the R2E085 blower would probably be 
> OK
> for most typical ICAS amateur use and would no doubt be selected by a
> commercial manufactuer for reasons of lower noise and also cost. However 
> if
> I were homebrewing an amp, personally I would go for the larger unit.
> BTW I thought there was a trend by the commercial manufacturers to use
> variable speed blowers with thermal sensors on the exhaust to reduce 
> airflow
> and hence noise when the amp is in standby or in low duty modes and then
> speed up to give the required airflow when things warm up.
> Regards
> David G4FTC
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