6K8G Triode Hexode Frequency Changer Military Valve/Tube (Te



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For sale a 6K8G (ZA5307) triode hexode frequency changer valve / vacuum tube, fully tested and working. This is one of the classic American "Magic 3" radio valve designs, used in their millions in 1930s & 40s radio designs. The triode forms the local oscillator and the hexode is the frequency mixer (changer), generating a constant frequency signal at the receivers chosen intermediate frequency.

This particular example is an early UK military import, numbered ZA5307 with War Department markings, which dates it as an early 1930s device prior to the introduction of the UK CV valve numbering system. An ideal item for those restoring military radio receivers of the time. It is in good clean condition, with all original markings. Recently tested showing no faults and good emission on both sections on my Mullard High Speed Valve tester.

This is an ideal device for those repairing vintage valve technology radio sets. A sensible price for an ideal chance to acquire a guaranteed working example of this historic old valve / tube.

Why waste 99p and the postage on an untested valve when you can buy a guaranteed working one from Helmore & Hunt. See our excellent 100% positive feedback on valves previously sold!


Heater = 6.3V @ 0.3A

Anode / Plate:  250V / 3.0mA / 1.3Mohm
Screen Grid: 100V / 3.0mA
Signal Grid: -2.0V
gm: 0.65ma/V

Anode / Plate:  100V / 3.3mA
Signal Grid: -0.0V

I do not sell my valves / tubes for 99p, as to test and select good working items that are some 60 years old takes time, care, equipment and knowledge!


I offer a full, money back guarantee if you are not completely satisfied with this purchase (see terms). We have been trading since 1927 so bid with confidence. Most of our valves / tubes have been in our own stock room for many, many years. See our EXCELLENT FEEDBACK on quality valves / tubes previously supplied!

We have thousands of valves / tubes in stock - standard and rare; US, UK and European. If you have any particular requirements, please send a message and if we have what you want, we will list it here.

We ship worldwide and are very happy to combine items for multiple postage.

GUARANTEE: In case of dissatisfaction, buyer must return item at own expense. We will only refund if you return the EXACT SAME VALVE / TUBE to us that you have purchased, with the heater still intact and passing continuity test. Believe it or not, some evil people have tried to send us back their dud tubes to try and get a full refund for a perfectly good tube we have just sold them! So, refund is a genuine offer, but at our discretion that we have been sent back what we actually sold you in the first place and that you haven't destroyed it through misuse! All returns under guarantee are limited to within 21 days of shipping.

PAYMENT: We accept Paypal, cheques in GBP, UK postal orders / bank drafts or wire transfers. Please CONTACT US FIRST before sending payment by a method other than PayPal - there will be a delay in shipping while we clear your payment if you pay using these other methods. We are happy for you to collect from Bristol, but will require payment in GBP cash on collection.

For more information, click [view offer] to the right side.