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THE AM BULLETIN BOARD => Military Amateur Radio Section => Topic started by: PA0NVD on March 19, 2018, 05:32:33 PM



Title: Fun little receiver BC 728 C
Post by: PA0NVD on March 19, 2018, 05:32:33 PM
I could remove this receiver from my sea container, it was at the entrance, and made some pics. For the people who don't know it, it is a single superhet  tuning 2 - 6 MHz in 4 bands. The selected frequency becomes a preset channel in that band that you can select with a push button switch. It is powered by a single 2 volt lead acid cell that can be charged from various voltages using a vibrator down converter to 2 1/2 volts A second vibrator is used to generate the HV
The set has a large whip antenna and is quite sensitive, the received band noise is many dB stronger than the receiver noise and can be used to tune the RF amp input and output circuit without a signal present.
You can imagine that I tuned the third band to 3705, AM  :)
In Holland I used it a lot to receive the AM net.  The last 20 years it was stored in Spain (where is much less AM activity) and I bought a 2 Volt cell for it before moving to CR
Here I switched it on and it worked immediately and was still tuned correctly, and that after approx 22 years of storage.
Coming days I will listen if I can hear some AM at 3705


Title: Re: Fun little receiver BC 728 C
Post by: KE5YTV on March 19, 2018, 08:27:11 PM
That's an interesting receiver. I've haven't come across one before. Thanks for sharing.


Title: Re: Fun little receiver BC 728 C
Post by: WB6NVH on April 22, 2018, 05:37:43 AM
It was a portable set intended to serve as a warning alarm receiver for gas warfare.  Gas warfare was not used in WWII so these did not see widespread use although the surplus market was full of them up to about 1960 in the USA.


Title: Re: Fun little receiver BC 728 C
Post by: PA0NVD on April 22, 2018, 09:01:08 AM
Didn't know that, thanks for the info. Very sensitive receiver, I hear here in CR USA hams at the whip.


Title: Re: Fun little receiver BC 728 C
Post by: AJ1G on April 22, 2018, 06:52:29 PM
Although not used for gas attack warning, I have read that they were often used for a similar function, air attack warnings.  The GRR-5 was also used for that purpose.


Title: Re: Fun little receiver BC 728 C
Post by: af6im on May 02, 2018, 03:19:14 PM
Never knew about this interesting little rcvr. Amazing that it fired right up after being dormant for decades. Thanks for posting about it.

AF6IM
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