[Hallicrafters] SR 2000 |
Donato Mascia
mascia.donato at gmail.com
Tue Jul 29 06:36:18 EDT 2014
Good morning Jim (11:30 AM Local), you are very kind
1) I have some valves is 8122 RCA Burle some red and others black, or a
pair of new red Burle. For now I have only been rehearsing with RCA, I do
not want to take risks with new valves Burle, the 8122 are very delicate!.
2) HT position corresponds to the P 2000 High Voltage.
3) Today I replace the R316 with a new 12 K 25 Watt came from Nebraska
Surplus.
4) The power antenna is a wattmeter-automatic tuner 1 KW.
5) in low power about 350-400 watts max; in Hight power *drops *to about
250-300 W max. always with the screen grid current stable on 15 mA.
6) after the maximum screen current of 15 mA does not have any increase in
power beyond the limits given above is that in LV & HV lowvoltage.
7) in normal conditions rightly plate voltage HV may drop in relation
to the greater
absorption of the valves, but in my case, the voltage drop is also
associated with a *decrease* of plate current (!) And output power. How is
it that a voltage drop is also associated with a decrease in current? It
seems to me an inconsistencythat suggests an alteration in the chain of
rectifier-capacity-resistors.
8) correct and stable bias current to 200 mA in both LV & HV.
9) screen grid voltage correct and stable to 300 Volt LV & 400 Volt HV.
10) the voltages are measured on the output of P 2000 on the connection plug
, and both the point of measurement of the transceiver shown in the manual.
11) no smoke or odor even in prolonged operation with HT applied.
I think to a fault in only P2000. Maybe a short in one of the capacitors 90
uF or alteration of the diodes?
Please excuse my verbosity, thanks and regards, Donato Mascia IZ5URV
mascia.donato @ gmail.com
2014-07-29 4:35 GMT+02:00 Jim Liles <hallicrafterssr2000 at k9axn.com>:
> Hello again Donato:
>
> How much power out can you get from the radio in low and high power mode
> with 15 ma of screen current?
>
> After tuning the radio for maximum 15ma of screen current, further
> increases in transmit RF drive should cause the anode current to drop.
> What do you observe when you do that?
>
> Kindest regards Jim K9AXN
>
>
> -----Original Message-----
> From: Donato Mascia
> Sent: Monday, July 28, 2014 5:39 PM
> To: Hallicrafters at mailman.qth.net
> Subject: [Hallicrafters] SR 2000
>
> Hallicrafters SR 2000 (serial No. 452000 142001), good conditions + power
> supply P 2000.
> Low voltage power supply tuning position for approximately 1800 volts. At
> the end of tuning by going to the location HT, about 2800 volts read on the
> instrument of P 2000, instead of increasing the anode current is lowered
> circa 20-40 mA, and a similar reduction also the output power (about 450
> watts according in position low voltage is passed to about 300 watts and
> less in position HT). Even the plate voltage drops from 2800 to about 2500
> - 2600 while the voltage of the screen grid appears normal and stable
> 300-volt low-voltage and high-voltage 400 volts. Change both 8122 and the
> driver no change. Other voltages and currents all normal. At the receiver
> nothing to report. Only resistor R 316 on P 2000 (12 kOhm Nominal 25 W) is
> about 45 kOhm. Replaced by one with the correct value 12 kOhm no change.
> The grid current without signal is sharply negative and goes up to about
> 10-15 mA with the signal. The rest all normal, proper the bias. Antenna OK.
> Could I have some advice for the anomaly ? Perhaps the diodes of the HT ? I
> thank you for your kindness and competence to restore the noble and
> venerable apparatus.
>
> IZ5URV (former I5MVD) Donato Mascia.
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