[ARC5] T19/ARC-5

[Henry Frederick "Meils" Meiseles]

Brian,

If you feel you must install  a small Ip or HB RF output meter  (e.g.. a 
horizontal-scale meter,  about 5/8"x 1½")
on the front panel of the T19, you could simply, use  mount it on a plastic 
or aluminum plate and drill holes to match the original roller- inductor 
dial-face mounting-holes (the original face as template) and reuse the 
original mounting screws, thus not necessitating any mechanical changes to 
the panel and simplifying retro.

BUT I agree with others on the list that an Ip meter can easily be placed 
externally e.g, at the PSU, which is what I always do.
I like continuous actual PA plate current monitoring, particularly when 
adjusting for proper antenna matching. Since you're using an BC-442,  you 
really don't need a panel mounted RF output meter, either.

Henry
oz3o n2nr


----- Original Message ----- 
From: "Brian Clarke" <brianclarke01 at optusnet.com.au>
To: "jsloss" <k7mks at comcast.net>; "ARC-5" <arc5 at mailman.qth.net>
Sent: Saturday, June 18, 2011 5:55 AM
Subject: Re: [ARC5] T19/ARC-5


> Hello Joe,
>
> As others have said, the first option is to do nothing to alter the Tx. In
> the end - your end - it will be worth far more. Further, the original
> designers supplied a vacuum capacitor with the antenna changeover relay
> (BC-442, RE-2 / ARC-5) with instructions in the operating manual for
> connecting it in series or parallel with the antenna feed to match other
> impedances than that presented by a short airplane antenna. Let me know if
> you need a vacuum capacitor - I have a couple of spares, and a spare 
> BC-442.
>
> A very keen Command colleague has added a completely reversible mod to 
> raise
> the output impedance. Lift the ground wire from the coupling coil on the 
> RF
> PA tank coil; insert a few turns of insulated house-hold mains wiring wire
> around the cold end on the RF PA tank coil - you will need to experiment 
> to
> get the right number of turns. Keep the loading coil in order to make fine
> adjustments as you change operating frequency. Damaging the front panel to
> insert a meter reduces resale value to less than 1% of SFA. If you want to
> use coax to feed your antenna, make up a small adapter between your coax
> connector and the output terminals on the BC-442 or RE-2; I have seen 
> later
> versions of these with a ground terminal close to the control cable
> connector.
>
> The only time you need to measure Ip is when setting up the padder 
> capacitor
> in the RF PA circuit, ie, looking for a plate current dip; you only need 
> to
> do it once - the plate tuning capacitor will track nicely over the whole 
> of
> the 80 m band. After that, use the meter on the BC-442 or RE-2 for 
> adjusting
> coupling / matching to your antenna.
>
> 73 de Brian, VK2GCE.
>
> On Saturday, June 18, 2011 3:17 AM, Joe Loss asked:
>
>> I'd be interested in learning how you modified your T-19 to provide
>> appropriate loading to a 50 ohm unbalanced line.. .  I'm at the stage
>> where I need to decide if the roller coil stays or goes!  I'd prefer that
>> it go which will allow me to install a small Ip meter.
>