[BC] trouble with an old BC-1G need advice

[dynotherm at earthlink.net]

How right you are. From the Gates BC-1F (ca. 1950) forward,
the Ep was always designed for 2.5 kV. That gives a load
line that will yield the best performance and is what the
modulator is designed for. Usually, Ip will fall between
520 and 540 mA if all is well. It will tolerate 600, NP,
but 833 life will be poor.

Good drive is 150 ~ 175 mA, the only problem you probably
can't get it in a 1T or 1G because the 807's won't do it
like the 813 did in earlier models like the 1F. Tune it up
for as much as you can get and still keep the 807's alive 
for 6 months (or a year if you are very lucky).

Phil Alexander, CSRE, AMD



-----Original Message-----
>From:  Milton Holladay <miltron at mindspring.com>
>Sent: Apr 3, 2008 5:22 AM
>To: Broadcasters' Mailing List <broadcast at radiolists.net>
>Subject: Re: [BC] trouble with an old BC-1G need advice
>
>1,000 watt xmtrs that employ 833A tubes in the usual plate modulated scheme 
>are designed to operate at ~2500 volts X ~540mA. Running much higher Ep and 
>lower Ip is not necessarily better.
> IIRC, the secondary of the modulation transformer is meant to see a load of 
>4600 Ohms to reflect a proper match to the modulators of 10,000 ohms p/p. 
>Since E=IR, 2500 = ~0.543  X  4600 gives the correct operating constants.
>Efficiency is usually ~70% for these xmtrs.........
>M
>----- Original Message ----- 
>From: "Bob Groome" <bobgroome at yahoo.com>
>To: "Broadcasters' Mailing List" <broadcast at radiolists.net>
>Sent: Wednesday, April 02, 2008 12:02 PM
>Subject: Re: [BC] trouble with an old BC-1G need advice
>
>
>> Seems to me you should be seeing:
>>
>> 4.47 RF Amps out for 1 kW
>> PA Plate 430 to 490 mA ( 600 is too high)
>> PA Plate Volts 2.7 to 2.9 kV (lower is not
>> better)
>> PA Grid 85 to 120 mA
>
>----- Original Message ----- 
>From: "Neal Newman" <cozy659 at yahoo.com>
>To: "Broadcasters' Mailing List" <broadcast at radiolists.net>
>Sent: Wednesday, April 02, 2008 12:18 PM
>Subject: Re: [BC] trouble with an old BC-1G need advice
>
>
>>  Need the Plate voltage to figure out the Power..
>>
>>
>>
>>
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