Thank you, Roman.

> On 24 Jul 2018, at 21:33, Roman <[email protected]> wrote:
> 
> Hi John!
> 
> VY glad about that info was interested for you!
> Alexander RN3AUS make an experiments with 11 Hz here, but in near zone. Not 
> so long distance.
> This is experiment and joy-toy, but no communication for caves -)
> 
> If I know any news about VLF communication for caves here - I let you to know!
> 
> 73!
> Roman
> 
>> Roman,
>> 
>> Many thanks for pointing these out. Some aspects of the French experiment 
>> were also described in CREGJ 89 and 92.
>> 
>> FERRA was also mentioned in CREGJ 89.
>> 
>> John Hey (SK) would be delighted for his cave radio to be described as 
>> “Professional”. It undoubtedly was of that standard, but was not 
>> manufactured commercially as we could not find a company to do that. Many 
>> people built Heyphones, over a hundred sets were built and approximately 80 
>> were built by John himself.
>> 
>> 73 John F5VLF