Parts Acquisition

Over the last few weeks I’ve been acquiring parts to complete the 1934 superhet receiver.  As with many projects around here, it seems a bit of luck plays a hand in some finds.

Through some casual searching online, I found a source ( for many of the necessary parts, including some useful items for future transmitter projects.  National ceramic tube sockets (4, 5, and 6 pin), cloth wire, vintage mica and paper caps, high inductance RFCs, National SE / ST style variables, and National vernier dial lamps were amongst the goodies:


I decided to try and source the IF transformers and crystal filter by posting wanted ads on several of the popular online “swap” sites, like eHam, QRZ, and, looking specifically for units from parted HROs.  After I had posted on, I noticed a for-sale ad posted hours prior offering parts from a HRO-7.  The HRO-7 is basically a HRO-5 with a facelift.  I made contact with the seller and acquired the crystal filtering unit, both IF transformers, and the BFO can.  In addition, I got the RF gain potentiometer and BFO trimmer cap (with BFO on/off switch):


Amongst the other parts I sourced from various places were the 2.5 VAC tubes (56, 57, 58, 2A5) and 6.3 VAC tubes (6C6, 6D6, 76, 42).  At this time I’m not sure which ones I will use in the final receiver, but since the characteristics between the different series are the same other than filament voltage, I can swap them without circuit modifications.