[ARC5] BC-230 first run

[AKLDGUY .]

WA5CAB wrote:

> These sets, like the WW-II vehicular sets, are designed to work into a short (< <1/4
> wavelength) wire or whip antenna.  The radiation resistance is low, nowhere near 50
> ohms.  For example, the A-58 Phantom Antenna for SCR-193 (BC-191) contains two
> 10 ohm resistors with switching to yield 5, 10 or 20 ohms.  Not a whole lot of room for
> antennas on a P-39 or a P-40.

Yep, that's why this set and the ARC-5 sets have the roller coils
(to simulate the missing length).

73 de Neil ZL1ANM


On 3/28/16, AKLDGUY . <neilb0627 at gmail.com> wrote:
> Terry wrote:
>
>> I'm rooting for yous. Bought one of those a few years back when
>> Dave was experiment with using the 6C4's in it. Got a pair of
>> coils for it but neither are dead on the 80 or 40mtrs.
>> Have also got a couple big Philco console that have 6A3's
>> in the audio output and was thinking these might be fun to play with.
>
> Great to hear you got yours going (with 6C4's?). Let us know how
> the 6A3's work out.
>
> 73 de Neil ZL1ANM
>
>
>
>
> On 3/28/16, AKLDGUY . <neilb0627 at gmail.com> wrote:
>> Glen Zook wrote:
>>
>>> I am not really familiar with the transmitter.  However, is it designed
>>> to work into a 5-ohm load?  That is almost a dead short where r.f. is
>>> concerned.
>>>
>>> You indicated a dummy load of 5-each 1-ohm resistors in series.
>>> I would try 5-each 10-ohm resistors to get the load impedance up to
>>> 50-ohms.
>>
>> An HF antenna on a plane is very short electrically. Consequently the
>> impedance is about 5 ohms plus some capacitance. This is the
>> impedance that the set and the ARC-5 transmitters are designed to
>> work into. They will not properly work into a 50 ohm antenna unless
>> some kind of impedance matcher is present.
>> I appreciate you reading and commenting, though. Thanks.
>>
>> 73 de Neil ZL1ANM
>>
>>
>> On 3/28/16, AKLDGUY . <neilb0627 at gmail.com> wrote:
>>> Dave Stinson wrote:
>>>
>>>> Inspect the coil connection posts.  Hard to get to
>>>> the backs of them but not impossible.  Make sure they connect
>>>> where they should, especailly ground points.
>>>
>>> Do you mean the wiring may have been modified by a previous
>>> owner (no, it hasn't been modified in any way) or that the
>>> connections are prone to going O/C with old age?
>>>
>>>> Are the 6AQ5 screens connected to plate or grid?
>>>> Must go to plate.
>>>
>>> They go to plate.
>>>
>>>> Jumper the RF Ammeter. Open thermocouple is
>>>> another common problem.
>>>
>>> That's easily tryable. I'll check that out when I return after lunch.
>>>
>>>> If not any of these, I'll get my manuals and
>>>> start scratching my head.
>>>
>>> Thanks. I wondered whether I had overlooked some setting.
>>>
>>> 73 de Neil ZL1ANM
>>>
>>>
>>> On 3/28/16, AKLDGUY . <neilb0627 at gmail.com> wrote:
>>>> Leslie wrote:
>>>>
>>>>> If the output tank circuit was "way off" resonance I'd expect more
>>>>> current in the plate circuit.
>>>>> My hunch is that there is a discrepancy between the resonant frequency
>>>>> of the grid and plate tank circuits.
>>>>> (But the grid cct is untuned.  Only the plate circuit is tuned.)
>>>>>
>>>>> I would suspect corrosion in the contacts somewhere - maybe the tank
>>>>> "C".
>>>>> I think that's C17.  Check the wiper on the rotor for C-17
>>>>
>>>> Yes, my instinct was that the final tank is way off tune, but in that
>>>> case
>>>> there should be more plate current and it should be 'dippable' to 25mA
>>>> at resonance. I'll inspect the rotor wiper, but the capacitor looks
>>>> pristine, so not hopeful.
>>>>
>>>>> If you make a "loop" with a neon on it, does the neon light?
>>>>> If you make a "sniffer coil" with a 6V or 2V incandescent globe does
>>>>> it
>>>>> light?
>>>>
>>>> The neon loop sounds like a good idea. I may pick up a neon at Jaycar
>>>> while out for lunch today, if they're open this holiday weekend.
>>>>
>>>> 73 de Neil ZL1ANM
>>>>
>>>
>>
>