Great idea....
I too am using 2 resistors for the HV return in my 8877 project. I wanted to
have a resistor in the power supply as well as in the RF deck. I used a 2K in
the power supply and a 2k in the amplifier chassis. The metering circuit takes
the ground resistance down to a few ohms in the RF deck.
I'm using the WD7S triode board setup and analog Simpson meters.
73
Jim W7RY
> -----Original Message-----
> From: higasa@plum.ocn.ne.jp
> Sent: Fri, 10 Sep 2010 12:20:53 +0900
> To: amps@contesting.com
> Subject: Re: [Amps] GS35B questions
>
> Hi again,
>
> Regarding a grid drop resistor
> I am using two resistors;
>
> A: a 500 ohm 10 W from HV- to GND in HVPS.
> B: a 500 ohm 10 W from HV- to GND in RF deck.
> C: a 3A Si-diode is also connected between HV-
> and GND in parallel with resistor B;
> anode is grounded, cathode is connected to HV-.
>
> I am using a 0.2 ohm shunt resistor for IP meter,
> and a 2 ohm for IG meter between these 500 ohm
> resistor/diode and the bias diode/cathode of the
> tube in the RF deck; these 500 ohm resistors
> practically provide no or little error on the meters.
>
> de Han JE1BMJ
> ----- Original Message -----
> From: "Marius Hauki" <rezycle.bin@gmail.com>
> To: <amps@contesting.com>
> Sent: Friday, September 10, 2010 7:03 AM
> Subject: [Amps] GS35B questions
>
>
> Hi, I am working on a new GS35B HF amp design.
>
> Some questions:
>
> -I would like to buy some sockets instead of machining them myself.
> Could you gentlemen direct me to a person selling sockets that
> normally have them in stock or at least can deliver within a month or
> so?
>
> -What is the proper "burn in" procedure for the GS35B? I was planning
> on running the filament of the tube for some time (how long time?)
> with proper airflow. Do I need to apply HV as well? I don't have a HV
> tester at the moment. I bought the tubes from UR4RLL. They look new /
> unused.
>
> -I am planning to use the triode control board from WD7S. Any things
> that I should be specially aware of when using that board with the
> GS35B (apart from the mod for higher bias voltage)?
>
> -I am planning 3650V on the anode. This is significantly higher than
> the "official" data sheets state, however I notice that the official
> data sheets rate the tube for military service with less cooling. Does
> 3650V look like an OK voltage?
>
> -I am looking for a SAFE way of running the HV cable from an external
> HV PSU cabinet to the RF cabinet. I know this has been discussed
> numerous times before, but again: what is the best cable I can use and
> what connector should I use? Did we reach a conclusion and some
> reccomendation on that question? I would like to avoid any possibility
> at all for the B+ (hv plus)connector connecting before the B- (hv
> minus) because that may place the RF deck at the HV+ potential if the
> grounding between the two boxes are broken. (I do not plan on hot
> plugging, of course). The minus lead should be isolated from the
> chassis since I plan on using a high wattage drop resistor from
> chassis ground to B- to be able to measure grid current.
>
> -Should I place the grid drop resistor in the PSU cabinet or in the PA
> deck? I was thinking that placing it in the PA deck would be safer
> because in case only B+ is connected before B-, the grid drop resistor
> would connect B- to chassis ground and not keep the PA deck at B+
> potential (No I am not going to hot plug the B+ connector, but perhaps
> some other operator will attempt just that. You never know what can
> happen in the mid of a contest battle)
>
> -I have read that running DC instead of AC on the filament is OK.
> However I have read somewhere else that it is not OK. I have an AC
> trafo, but if the primary voltage varies, the filament voltage could
> be too high or too low and this may hurt the tube. Instead I would run
> a regulated DC supply, since the filament current is not that high.
> Any comments on that? Alternatively, any clever way of regulating the
> trafo by a small series drop resistor or something?
>
> 73
> LB3HC
> Marius
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